A supercunductor plate would cause it to be locked together lol. It would be almost impossible to slip it. That's essentially how magnetic levitation works.
@@rubiconnn but then it could be controlled. Connecting a grounded resistor to the superconducting plate would disturb the eddy currents, and provide momentary 100% slip. You could switch it on and off PWM style to tightly control slip. Now we just need room temeprature supeconductor. :(
Yeah that would induce instantaneous eddy currents of such proportion to effectively bolt it together, it would be an expensive, weighty and very cold cog.
That's why I regularly substitute lectures with RUclips videos - sometimes there is incredible stuff to find, that saves the student (me) hours of agony and self hatred. Hehe. Idk what these people do differently, maybe it's because they're closer to the point where they didn't understand it themselves than most professors are, but they sometimes have an incredible efficient way of teaching. (Helped me most with theoretical physics stuff)
You are not good at physics. Because you don't understand the science behind math, electricity, chemistry and biology. You are not a professor. You are just on papers, but the reality is painful. If my kids will have a teacher like you, I will remove my kids from the school. You are a shame for all the italian schools and physics and science departments.
@@braindecay9477 Personally I suspect it's just numbers. If there's hundreds of youtube videos explaining an idea, you're only likely to see the best ones, and the many many terrible videos just drop into obscurity. Whereas with your actual college course it's unlikely you have all the best professors for every subject. Although that does create an interesting idea. Imagine if you had access to lectures from hundreds of professors worldwide and your tuition went to the ones you watched the most.
Well I don't think most physics teachers have a small team, a budget that allows for cnc machining and 3d printing custom parts, and weeks/months to dedicate to creating a single 30 minute lesson (when would they do their marking?)
The side by side comparisons are astonishing, it’s amazing to visualise the different behaviours induced by different configurations of magnets and weights
Tom is brilliant, I wouldn't be surprised at all if the heat generation turns out to be a huge positive for future project potential, surely this magnetic contactless set up could harness all sorts of free incidental energy
As a bicycle mechanic over in Germany I gotta say, I really love your bike related videos. They give me great aspiration, sadly I lack the funding to copy your concepts for my own fun. But they make great talk in the break room!
In another life, I was a bike mechanic too. I probably enjoy as much these videos as you. Now that I’m doing more software and hardware, after building a few robots, it tickles me to try and build a braking system idea I had a long time ago!
as a bike mechanic in Germany, do you work on Rohloffs or other internal gearhubs. How do you like them? If this magnetic clutch/gear works, it would be fantastic!
I'm wondering if being able to vary the strength of the magnets (by making them tiny electromagnets) would make it a practical device. Sort of like gearing through magnetism. Probably not, but it's so tantalizingly almost useful.
By having Flux collector on each magnet of Faris metal you could greatly increase the magnetic strength of each magnet in the desired direction. If done correctly it could reduce the attraction to the chain.
The alternating magnets for stronger eddy currents was a great idea! You might want to look into the Halbach Array (a specific way of alternating magnets) that makes the field strength even higher. I think it might perform better than only alternating the magnets.
Exactly what I was Thinking. Also can't he put a steel plate on one side of the array to cancel the magnetic field so he won't have issues with the chain and spokes?
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Also it makes magnetic field much stronger on one side (the clutch side) than on the other side (the chain side).
@@oodmboo If he made the diameter of the disks bigger he could fit more magnets in to give him the torque he needs to go uphill and it would also solve the spoke problem since the spokes are already sloped away from the magnets further out. Might run into torque issues breaking the disc though.
I was very dubious at the start, thinking, “oh, yeah, another magnets perpetual motion scam”. . . but no. I learned a lot from this. . . an honest presentation. Nobody’s going to win the Tour de France with this setup (especially me, a 79-year old time triallist)😊 Well done, sir!
Is there a good way to redo this experiment with electromagnets and then be able to variable control the strength of the clutch? Also with electromagnetism you could possibly also have the brake do regenerative braking to recharge the electric battery. Would be a great way to continue this project into a more usuable concept. Im not sure the specifics on how it would work, but would love to see it built. Thanks for the video tom and hope you make some more videos soon.
^^ I made a new account and seeded it with a Playlist of content types that I wanted and now my algorithm is much better than the old account. Probably a good idea to do this every few years to get a fresh look.
I think you may have missed a trick. Putting an iron backing plate on both back sides of the magnets (ie facing opposite the copper disc) would give you two additional advantages. One being the flux would be more constrained and not grab the chain/spokes and the field facing the copper disc would be more intense. However the heat due to loss will definitely be more severe when the clutch starts slipping and will equally affect the magnets, which in your case, due to their size might have been a bit cooked too, but cooled faster due to less thermal mass. But in theory, the increase in efficiency would mean less slipping. Another factor is that neodymium magnets permanently lose their magnetism when heated to approximately 85deg C, which is why when these types of clutches are used in industrial applications, there is usually a significant liquid cooling system that either flows through the clutch components, or the clutch is immersed in it. They are very precise and consistent (repeatable) clutch designs that can absorb massive dynamic changes in force, so they are very useful in other applications, where longevity and smoothness are more important than efficiency in the force transfer. They are also used as brakes and dampers for similar reasons and also have more traditional lockup mechanisms and or clutches for greater efficiency when output (or input in the case of braking) has reached a certain speed. Obviously these are stupid expensive, mostly due to materials, proper matching of the specifications, and definitely being customised for the application, not to mention bulky, but sometimes they are worth it, to solve particularly difficult problems where traditional force coupling mechanisms don’t work as well. Anyway, sorry for being “that guy” at the party, great video and demonstration of a very useful and niche device!
Tom, this response is on the money. Ferrous materials will provide a much lower magnetic impedance than air, increasing the magnetic flux density experienced by the copper. So putting some of the outside faces of the magnet groups will improve performance. Again, on the money; watch out for heating and ideally turn that ferrous material into a heatsink for the magnets. Finally, milling a shallow pattern into the copper to sort of turn it into a centrifugal fan, (increasing air turbulence and heat transfer) may also extend the operating envelope. Mind you, it will always be lossy. Maybe it's more of a mobile cardio machine?
Electro mechatronics engineer here and were about to write pretty mich the same thing! However I disagree on the heat part... Yes the magnets suffer from higher temperatures but the heat is generated in the disk and not in the magnets. The suggested ferromagnetic parts to close the magnetic flux would alsobserve as additional radiators for the magnets to get rid of heat.
Your meticulous research and trials of materials and forces is truly impressive. Then to advise us that it didn't work as you had hoped shows your humility. Thanks for sharing this whole story.
The answer is seen in electromobile vehicles- Alternating current (in motor wire-windings) is far more efficient than permanent magnets only (which are also present in many EV motors). Also stopping power in EV regenerative/recuperative braking had same weakness as described in this video. But - with alternating current oposing the magnet rotation, it can be managed to fullstop in most current EV vehicles. Which translate to even not using normal friction brakes/pads at all = rusting. So this research is not completely wasted- it just needs to simulate EV motor = induce some current in copper disc (made from thousands of copper wires, insulated of course). And electronics with variable frequency of alternating current, made by using Gate-transistors. Of course it is not needed as you can buy such a bicycle now, but- exactly the same proces they do in Tesla, Mercedes factories/labs.
I would suggest utilizing the Eddy currents to store energy so it can act as an electric bike when needed. The heat is generated from those unutilized currents. That would solve your inefficiency.
Kind of like regenerative braking? Using the brake force to store some "losses", and of course, that would help it brake more efficiently, as well (especially at back pedal)
This channel was new to me. I was blown away by the concept, quality of the build, quality of the experimentation, and the quality of the video production. You, Sir, are really good at this!
There's another guy, James Bruton, who does very similar experiments, uses 3D printers, uses a very similar methodology AND sounds like he is from the same part of the world as Tom here. I think they should work together on a project! For example: ruclips.net/video/6YG8CsCE0WM/видео.html
Hey that's pretty neat to learn about the alternating polarity creating a greater resistance. I didn't think of that. You could print a little cube grid that holds multiple magnets with opposing fields and probably get a much more impressive slow down when dropping it down a pipe.
If you thought about it for a minute, you would know this. Here's an important thought experiment: what if you replaced the ring of alternating magnets with an actual machined ring neodymium magnet concentric with the axle? How much torque would be transferred? Zero. The answer is zero. It would spin freely. Eddy currents form when there's a *change* in magnetic field, not just whenever there's a magnetic field. So the more changes there are, the more eddy currents form. The only limiting factor is when the magnets get so small that the changes in magnetic field don't bridge the gap from the magnets to the conductor.
@@Squancherino You people do understand that the efficiency asymptote this thing is approaching with more effective magnetic fields is identical to just gluing the two plates together, correct? There is literally zero benefit to this clutch? I feel like everyone is missing this fundamental concept.
Making the copper plate thicker would reduce the number of magnets needed by decreasing the resistance for the eddy currents. And as other people have commented mounting the magnets in a steel mount would also improve the performance by helping to concentrate the flux. Similar just for kicks project would be to try to convert this into a homopolar motor regenerative braking setup with some big capacitors.
Also making the plates from a larger diameter plate would result in less input speed equal to the increase in primary drive sprocket getting that magical speed differential is probably key to better transmission and more heat dissipation
There is a bicycle trainer device called the Kinetic that has used this principle for decades. The resistance unit is hydraulic, that has a sealed chamber to prevent leaking. It’s hard to seal around a shaft, so they drive an impeller inside the sealed chamber with a magnetic clutch. My trainer is decades old still works great and no leaks.
One factor you seem to have overlooked is that if you want higher braking at low speed you could always just pedal backwards and increase the effective relative speed of the wheel vs the magnets. I do otherwise agree with people's suggestions of reducing the amount of copper used. I'd also suggest, from my limited electrical engineering knowledge, that you cut air gaps between sections of the copper, as that should cause greater eddy currents since the air will act as a dilectric and theoretically cause increased resistance. Will admit I'm unsure if that'd improve the effective coupling overall, but it seems like something that would at least have an impact.
Hi Tom The checkerboard is only useful if you also want drag in the left-right direction.; generally the magnet diameter should be greater than the gap between facing magnets. More importantly, please look into "back irons" - these will easily improve the effectiveness by 2x or 3x and shall also eliminate the problem of the chain sticking to the magnets :)
Yes! I think this would probably double the performance at least. Mumetal is ideally suited for the job (which is why they use it in hard drive voice coils)
Would it not work better if there were magnets distributed around the disc ? (perhaps at pitch centres corresponding to say 9/10ths of the pitch of magnets, to get a sort of vernier effect). I guess the poles on the frame would want to be opposite polarity to those on the rotating disc. You'd want magnets both sides of the disc, to balance out the axial forces.
@@Gottenhimfella Quite a few drawbacks to your scheme - The damping (i.e. conversion of kinetic energy to heat) happens in the conductor, not in the magnet. A magnet shall store energy as potential energy (and then is mire like to demagnetize too, but that is a different story). So, to convert KE to heat, a conductive disc is essential. The added moving magnets shall add inertia to the rotor (non-issue in a bicycle, agreed) Second issue is that of axial (parallel to the axle of the wheel) force - rare-earth magnets of this size pull hard - a symmetric construction with two sets of fixed magnets and one moving conductor has no axial forces, and hence can be thin and slim.. to work-around this, perhaps 8/10th or 7/10th would be better. The third issue is cogging. Even with the Vernier, you would feel some. The advantage in your scheme (if I understand it correctly) is that you eliminate the air-gap on one side of the damper. The disadvantages that you have to pay as a price are, imo, not worthwhile (at least with my understanding of your described concept. Feel free to 3-d print a holder with 7-magnets and 10-magnets arranged in a circle and try twisting them against one another :) (without a conductor, it will feel more like a detent than a damper)
Magnetic coupling is very useful for underwater applications, where you want to disconnect the propeller from the internal electronics. Back when I was in highschool, we built an autonomous underwater vehicle and faced a real problem with isolating the propeller's entrance.
But don't the magnets need to be really close to the disc for reasonably efficient power transfer, so if you have to put the waterproof bit of the boat/vehicle between the two then that's quite a lot of spacing you didn't want. How well does it work across 3mm of fibreglass (or whatever is sufficient to keep the water/pressure out).
What happens if you pedal backwards? Would that provide more braking force? How would the addition of an electrical current affect the resistance? Great videos! I really enjoy watching and learning such interesting concepts!
One of his tests demonstrates that the torque generated was proportional to the difference in RPM between the disc and the magnets, so yes, pedaling backward would increase this difference in speeds, and therefore produce more braking torque. The other question is interesting. The eddy currents that the magnets induce in the copper disc flow in a ring around the magnets, lagging behind the magnets because it takes some time for the current to die off once it's induced into a particular path. This is really how the torque is created - the ring of current induced by the magnets produces an opposite magnetic flux to that of the magnets, that's constantly trying to align itself with the magnets, so any rotation of the disc produces a "back torque" that opposes the motion. If you were to fit carbon brushes either ahead of or behind the magnets, current passed through the disc through these brushes will also produce a torque for similar reasons. You will have created a DC motor, but this would be very inefficient because the current you apply to the brushes would not just flow through the copper directly between the brushes, but also though many other paths that would not produce usable work. This could be improved by cutting slots radially at intervals around the disc, between the brushes, which would reduce the undesired currents without affecting the intended current path, but now you're getting closer to a conventional commutated DC motor. Which sounds like something interesting. However, if you look up radial flux brushless DC motor, you will find that this is very close to what is already being used for low-speed, high torque brushless motors.
Pedaling backwards does increase the braking resistance, because it means the sprocket RPM becomes 'negative' and the net RPM difference becomes larger. Regarding electrical current, the current in the disc is not DC but it's a localized AC current which moves along with the magnet's rotation. To get the disc to spin using electrical current, you need to apply a rotating magnetic field through a set of coils. In his experiment, the magnets are replacing the pole pairs of a motor.
@BrightBlueJim Thanks for the response. I'm not an engineer and am not up to speed on the theory of DC motors. I know enough about electricity to be dangerous. My crude thought process was that an electrical current might increase the amount of torque that is being applied to the wheel from pedaling and provide a better braking action. Thanks again!
@@BrightBlueJim The homopolar generator designed by Michael Faraday was a similar design as well, very cool seeing how this is basically that but with no wires connected to it.
Also: If you look at induction motor rotor design you see that they commonly have slots. Part of the reason for these is to reduce the reach of eddy currents that cause those heating losses you see. So cutting a bunch of wedge-slots in the copper disk would probably improve performance a lot
@Blox117 right. And if you design the magnetic coupling to handle the cruise power, the acceleration is limited to what that power can provide It's not a big deal, but it does show on the real-world performance tests
@@Azeazezar if they travel too far, they generate heat rather than force. This is an induction motor stretched out onto a plane, with the moving electric fields provided by physically driven permanent magnets instead of AC/stepper controller driven electromagnets. It's an elegant and clever device, for certain.
In home exercise bikes, a magnetic brake is sometimes used in the form of a set of fixed permanent magnets (or electric magnets in expensive devices), and a perforated metal disk (similar to an aluminum alloy) that rotates through an upshift pedals. The adjustment of the braking force is regulated by changing the distance of the magnets from the rotating disc. Excess heat is dissipated from the disk into the air by means of a small impeller with blades on the disk shaft. Thus, it turns out to achieve a fairly wide range of loads (from 50 watts to 1.5 kW) with modest dimensions of the device.
Its also used for high speed trains to stop it from a high speed. Its a huge magnet thats dtops down to like a millimeter above the rail. de.m.wikipedia.org/wiki/Magnetschienenbremse
@@jonkess2768 Not just on high-speed trains. Old trams had an electromagnet braking system on the rails. But in both cases the rail is steel, and permanent magnetism is used; in the case of aluminum, a different principle of operation is used, due to the induction of an EMF in a short-circuited circuit, the so-called “Foucault current” or eddy currents, which occurs in a conductor in the form of an aluminum disk its own magnetic field arises, which slows it down. By the way, the same problem occurs in speakers, which reduces the output at high frequencies due to increased electromagnetic induction, and to compensate for this phenomenon, copper short-circuited caps are used on the core of the magnetic system.
I think the best use of this sort of thing would be if you had a normal chain drive, but you could engage and disengage it like caliper brakes for coasting down really long and/or steep hills. Much quieter and no brake pads to wear out. Also have conventional brakes for emergency stops.
It's always so mesmerizing to witness eddy currents. I was playing with magnets and a copper pipe a while back and it's so so interesting to see it happen. The clutch idea is interesting, I could see this being useful in some kind of application that may get sudden changes of resistance, and it would save the output shaft of the motor. Rollercoaster brakes also work similarly to this.
Tom, I really like your focus on the subject of your videos. Been watching you for years and as many other channels over-hype, fast-cut, force jokes, etc... you've stayed one of my favorites. I can watch you when having a slight headache and it's not too much but rather interesting and calming. Also, good on you to commit to all your interesting ideas, figure out if something would work and show it. You test so many things a lot of people probably have wondered about but no one has seriously tried yet, let alone shown it to the world. Please keep being you, lovely to watch always!
I noticed that this is much the same as the way my exercise bike works. There are two belt-and-pulley setups that spin an aluminium disc between a couple of magnets. The resistance is varied by moving the magnets in or out. And yes, my efforts go into making the disc get hot!
The purpose of your exercise bike is to give you exercise - to make you work, by resisting your pedaling. I'm sure you will notice that the disk between the magnets warms up, because your work being used to generate heat. In Tom Stanton's case, however, the desire was to convert the work into distance. So the desired outcome of the two machines is opposite, one to waste your effort as heat; the other to use your effort to go so0mewhere - but the actual outcome is much the same. Work produces heat. Your exercise machine uses *_all_* your work for heat generation; Tom's machine gives some distance travelled, but it is limited by its inefficiency, which produced heat.
@@DownhillAllTheWay i agree totally. Which was not difficult because you basically told nothing new. It is basic logic. IF your exercise machine was using your work to give you some distance it would become a problem because you need a large room to house it in. Btw, you could just take a bike outside if you want some distance travelled while you work. The whole idea of an exercise bike is that it is stationary and doesnt travel any distance. SO by that way of thinking i would say it is kinda pretty logic what you explained. And, some would then be very rude and say: Jeez, thanks Sherlock. But i wont. I just think it. >:) (yeah, i am a stupid dutch guy, so i blame it on that)
@@DownhillAllTheWay o damn, sorry, i forgot to add this but it has to be added. The first part you typed: The purpose of your exercise bike is to give you exercise. I forgot to add it but it should be somewhere in the start of my comment to make it more clear why i would think: Jeez, thanks Sherlock. >:) Just a joke sir, just a joke.
@@bertjesklotepino Hi there! Don't worry, I took it as a joke. I was commenting on the video - not trying to explain it - but I'm sure you understood the intent of my comment. All of the best to you, Sir!
Two points I'd have tested; 1. how much does it slow you if you pedal backwards? 2. what does it do for controlling speed when going down a hill (something steep enough to normally require braking)? Interesting as always! 👍👍
I am never more excited then when i see a video from Tom. The step by step research to prototype of an idea is unmatched in my opinion. Truly top notch content!
I feel like you could put this in a car to assist the normal clutch and reduce clutch wear. Especially the dual clutch ones would greatly benefit from this.
It will make a big difference. The speed of the magnets and copper disc relative to each other determines how much force they exert on each other. So at higher speed he exerts a lot of effort just to hold the pedals still, but at lower speed it should be possible to pedal backwards and therefore create enough force at the wheel to stop in a reasonable distance.
@@jackbauer2698 if you look into the world of fixed gear cycling, you find that people can break the traction of the rear tire and lock it by pulling up on the straps that they install on the pedals. The only thing preventing you from pedaling backwards is the traction of the rear tire.
You could try mounting the magnets as a halbach array, it's used to point most of the magnetic field in a single direction meaning you'd get more Eddy currents and less chain sticking!
And get a stainless steel chain And a "spring toothed?" One way gear on the front sprocket for coasting AND a way to close and lengthen the gap between the magnets and the copper disk for gearing AAANND enclose the magnets to separate the road environment because they'll clog themselves with iron dust.....oh and some hand brakes for stopping. By the way, your copper disks will warp from the heat so make them easily exchangeable.
If you go halbach the distance between mags and copper becomes more accurate(making a gear ratio situation more difficult to "tune in") so heat and warp aren't worth achievement of gearing. Gears, cogs and chains beat you damn engineer "thinkers" out every(almost) time. You might try focusing more simple, less complicated.
You had an idea and you concisely show how you went about implementing it and the methods you use. Thank you Tom for inspiring the younglings, I have no doubt we'll get some amazing innovations in the future, influenced by your ability to educate. Even though I pay little attention to the numbers and equations I still end up feeling slightly smarter from watching your videos.
Remember that the Lord Jesus Christ died on a cross for you because He loves you so much. He then rose up from the dead three days later The Ten Commandments are called the moral law, (most of us are lying thieving blasphemous adulterer at heart and deserve hell) you and I broke the law, Jesus paid the fine. That’s what happened on that cross. By believing that Jesus died on the cross and rose up from the dead 3 days later and not just confessing your sin, but also repenting of all sin you have done and putting all your trust in Him in prayer, He will grant you everlasting life as a free Gift
@@Billybobble1 That bible bashing fool didn't even knock on your door before randomly spouting his completely irrelevant BS at you. Pretty damned rude I'd say. Completely agree with your assessment and way of seeing this and others of his videos. There's so much I'll never understand but, I still learn from this sort of thing. One question I had he did answer was, whether the resistance was converted to heat or not. If it hadn't, it could have opened up a few more interesting possible uses like speed control of things without wear, obviously but, heat can be a problem too and a non heat generating device could be extremely useful in some situations. Still very interesting stuff though.
From an engineering standpoint, I see two obvious improvements. Although copper is a better conductor than aluminum, aluminum is stronger and better for transferring work. Use aluminum instead. For the magnets interfering with the chain, modify the sprocket to cross the whole axle and put the magnets on the other side. As for coasting, modify the clutch so that the bike rolls freely even if the sprocket and aluminum plate are stopped. I wouldn't even try adding a magnetic braking system to this setup because that would transfer a ton of momentum to a small part (the sprocket area) which would wear out the sprocket very fast. If you wanted magnetic braking I would suggest a secondary aluminum plate on the chain side of the wheel. Make it fixed so it moves with the wheel at all times. Then have magnets slide in and out from a fixed position on the bike, probably under the seat and well away from the chain.
I'd love to see a return to this experiment with more designs and maybe some alterations with additional parts to see if this could be further built on as a viable drive method. The concept seems really awesome, and I'm sure there's got to be some utility in this somewhere.
It could be the basis for a new kind of automatic transmission in cars. Instead of an epicyclic gearbox driven by fluid, pressure and friction with wet clutches and bands, it's magnets!!! Clutches, bands and the hydraulic fluid in an automatic transmission will wear down over time, but magnets will probably last a lot longer. The magnets could be turned on and off electronically (they would be electromagnets, not permanent ones). Instead of clutch packs being pushed together by a piston, it's a current turning on electromagnets to make two discs lock together. The current would replace fluid going through solenoid valves in a valve body.
I have an idea for you mate. You could have a variable gearing effect by mounting the magnet cages attached to radially mounted springs. Mill slots in the disc around where the magnets sit under spring tension to reduce the eddy currents formed there. Use the centripedal acceleration to have them push outwards from centre and thus engage with the intact portion of disc on the perimeter at an RPM detemined by the spring rate. You'll have basically combined the centrifugal clutch with the magnetic drive.
I agree... He definitely needs to make a version 2, with some kind of centripetal action, because he wants a CVT. I'm not clear on whether the low RPM engagement should be at the outermost diameter of the copper disc, or the innermost, for the proper torque multiplication (I think it should be on the outermost at 0 RPM and move towards the center as wheel speed increases).
Great work! I think this is essentially an induction motor. What helps the induction motor work more efficiently will help this clutch as well, e.g. adding slots to the disk to limit the directions of Eddy current, adding iron cores into the slots to increase the magnetic flux density (B = muH)
An interesting experiment - I was watching this with my son, who did an engineering foundation at uni before his computer science degree, and I predicted the heat problem. Well done - it didn't work as well as you'd thought but it's a good experiment.
It will give you a stronger field but you also have to keep in mind that he didn't much space to mount the magnets. The magnets would touch or overlap with the chains and spokes if he would use the halbach config
@fischX it still might get in the way. The spikes as well if he puts the magnets on both sides. Easiest solution is to use smaller cube magnets but those magnets are probably not as strong
wouldn’t it just give you a stronger field on one side? so instead of a bunch of change in flux from north to south from the individual magnets to a change in flux of let’s say north to nothing but with a bigger north? would it actually be any better?
Halbach array would give you even more magnetic force per magnet given to the field direction you want. Of course you would simply heat your disc faster, so there's that. This is a super interesting concept though, for sure! You could also have direct magnetic interlock with a squirrel cage style ferro-magnetic core, like how induction motors work. I like the idea of creating a 0 friction gap in the drivetrain.
I wonder if he could get the copper hot enough that it stops being able to produce eddy currents. I know heat can kill a permanent magnet and hot iron won't stick to a magnet until it cools down.
@@andrewdescant I don't think you could reach those temperatures by pedaling outdoors, since the rate at which it loses heat increases with the difference in temperature vs the air. Would be wild though
Was thinking the same thing. Halbach arrays are often used in permanent magnet motors due to the lower weight and cost. It would be perfect for a project like this.
Wrap coils around the magnets and power them through an adjustable source to get variable torque coupling strength. If you put rotary encoders on the wheel and pedal crank you could implement a control system that always allowed a peak efficiency to be maintained for the pedal angular velocity. You could also implement kers on braking using the same equipment.
Great video, with brilliant visual comparisons. A few options to make life easier: 1. Use a disk hub (machined mount ready to use. 2. For mag interference with chain...Use belt drive instead of chain... they are superior in some ways and used by touring cyclists.. 3. For spoke mag interferrence, "string" spokes are already succesfully used
In case you weren't aware, mag clutches do exist and are in wide use, up to around 20 horsepower I believe. Should be no issue for your uses. I miss the air engine videos.
I think magnetic clutches use magnets on both sides? So it'll be equal speed up to a certain torque. I doubt anyone would want to run something with constant slip.
This is cool. If you decide to revisit this idea, I suggest you use a one-way clutch bearing for freewheeling and also add a U shaped back-irons for the magnets. This helps steer the fields in a shorter path and should increase the flux (IIRC) in the gap on the copper disc while reducing the magnetic forces on the chain and forks. Soft iron is best however plain steel should be fine as the magnetic field in the magnets are 'static'.
thats good suggestion. It would increase the torque for that design but not the efficiency of the system right? The main losses are in the copper if I understand it correctly.
@@LaggerSVK My experience with electro-magnetics is somewhat limited. My most recent experiment was a axial-flux motor for a heated stir plate I was making. I couldn't source suitable materials so I recycled the windings and core laminations from a large transformer to build it; not ideal for the frequencies that I drive it at but it ended up working reasonably well.
Just thinking about the problem with coasting: Would it be possible to make some sort of bearing or mechanical system so that the chain can 'lock in' and 'lock out' so that the magnets can still move with the wheel when the pedals are idling? Maybe a motor on the hub instead to counter-act the resistive difference? Kinda cheating though & probably way too complicated to be practical...
I was familiar with this phenomenon from roller coaster brakes, but you explored far deeper than I had ever seen before. Fascinating video and good explanations.
That was a brilliant, thoroughly well-thought and very well executed way to find out something is a not such a good idea. The effort put into this is admirable!
Watched a number of your videos. So nice to see someone who truly understands engineering, can explain it well and actually make some impressive things. Keep up the good work!
So, if stopping pedalling means an applied braking-force, then that will be very inconvenient any time you've pedalled long and hard enoug,h and only need to use the bikes inertia (like downhill, or any circumstances where freewheeling is advantageous), then you're stuffed!
That was incredible, thanks a lot! Two improvements are yelling to be done from a bike tech perspective: 1. just use a hub with a disc brake mount. It's exactly what you are looking for. (attaching a metal disc rigidly to a bike wheel) 2. use a bike with a chain shift as a basis: when you remove the cassette, you'll have a lot of clearance between the wheel and the frame Also I'd bet that a FDM printed sprocket in flat orientation out of nylon will outperform any resin printed sprocket
To add to this, consider trying a halbach array for the magnets. Also I know your intent was to get somewhat of a CVT effect, but continuing to use a gear cassette will allow for you to keep a more ideal slip angle with the copper.
I actually think this project is really interesting. Unfortunately the transfer of torque will always be determined by the change in magnetic flux. Meaning that you will have to pedal faster to get it going and keep it going.
@@tataduzy4260Yes, most current EV vehicles, with MOSFET transistors creating alternating current. Highly effective and only 10-15 kWh/100 km = 10-100x less than combustion motor. What is the problem? Calling BEV electromobiles "vehicle"?
@@comeonandslamandwelcometot2418 ok I thought so, just "gramar nazi" problem. It is normal when some category/abbrev became more common, it takes the semantic form of adjective/subject or even verb. Like we have AC + DC, but if you are talking about current, you also say "Now we switch AC to DC current in a circiut" sometimes. Or something like Congress resolution R268, abbrev used in many countries to add a certain level to complicated bunch-of-numbers and abbrevs, which are quite common in legislation. Especially if it is generally-targeted text, which youtube viewers surely are. And using frequent abbreviations adds confusion to text (for most not-profi readers). Therefore some, maybe dubious double info, adds comprehensibility, not reduces it. Like: problem of Postal Codes or Social-Security numbers or other codes, which contain dubious but failsafe information, even when you do not understand or make error. As you surely noticed on youtube or Twitter where many people use some "their best years military" abbrevs, or T9 auto-complete on mobiles = lots of uknknown shortened words. So ok, and now whatabout fact, not form?
You have to admire Tom's enthusiasm, he had an idea and he set about trying to bring it to fruition. Not all experiments work , but I am sure this attempt has brought him some useful insights of what he might try next.
2:25 this is sweet but you need to account for the moment of inertia... by adding some extra weight on the disc for example. side note, on a bicycle you'll probably want the lighter material... 11:10 by intuition I would have attached the magnets to the wheel, not the pedals: you'd save on the zip ties ;-) 14:57 yeah obviously... it's like the arrow halving the distance to the target each time you look at it ; the clutch alone will never bring you to a complete halt 15:54 I was waiting for that one XD the 8kJ obviously don't account for the energy dissipated in the air. Please please please try again with the thermal camera mounted on the bike while riding! We want a graph!! I'd really like to know what happens to the torque transfer capacity (and heat losses) in relation to the temperature of the copper disc. I pretty much knew where this was going, but this is brilliant : good preliminary testing, and I've been looking for a way to transfer torque without using hydraulics and this is just what I needed! Thanks!
Amazing idea! You can also separate copper segments into angles. This way the current must go in and out of radius. Your coupling will be much much greater! You can also drill lots of holes in the copper plate.
@@1800Supreme well steel is not as good as copper. And you'd need a battery for running the electromagnets. But the advantage is that you can switch them on and off to create some kind of a gear ratio I guess.
The magnets on the other side of the disk we cant see may be interfering or attenuating the magnetic field. I would test by first removing them leaving just one side full of magnets and the next test with different patterns, e.g. opposite sides, same plane. also using metal back-plates on the magnet helps allot [S N] |Cu| [N S] [N S] |Cu| [S N] config 1/5 [N S] |Cu| [N S] [S N] |Cu| [S N] config 2/5 X X |Cu| [S N] X X |Cu| [S N] config 3/5 X X |Cu| [S N]\Fe\a X X |Cu| [N S]\Fe\a X X |Cu| [S N]/Fe/b X X |Cu| [N S]/Fe/b X X |Cu| [S N]\Fe\c X X |Cu| [N S]\Fe\c config 4/5 d\Fe\[N S] |Cu| [S N]\Fe\a d\Fe\[N S] |Cu| [N S]\Fe\a e\Fe\[N S] |Cu| [S N]/Fe/b e\Fe\[N S] |Cu| [N S]/Fe/b f\Fe\[N S] |Cu| [S N]\Fe\c f\Fe\[N S] |Cu| [N S]\Fe\c config 5/5 d\Fe\ or /Fe/a represents iron plates that connects two magnets together, one magnetic pole to another on the same side. a to a, b to b, c to c..... X X represents the absence of magnets, Iron, or Copper. Nothing basically. |Cu| represents the copper disk [N S] or [S N] represent dipole magnets, N being North and S being South
You always have the most interesting bike technology builds. Your anti-lock brakes from a while back inspired me to design my own and I love the way they work
I would recommend not using a disc of copper, but an annulus. You could have "gearings" by having several nested annuli with notched / cutout bracing supporting them, and different gears would correspond to different magnet arrays for each radii associated with each annulus, where the field strength would differ for each array. But either way, this was a very cool (warm?) experiment!
@@stephencummins7589 Thanks for your kind words! I was only spelling out an idea. Not diminishing what was done and obviously he put a lot of effort into this. I apologize for not having a RUclips channel and extra money to build projects to have a moral equity in commenting here. I know that everyone has the degrees of freedom in their life to do that and I'm sure you've gonna ahead and pointed out all of the other commenters' lack of platform content when they've made suggestions or had opinions. I will refrain from putting my musings and ill-considered ideas online in the future so as to not offend anyone's delicate sensibilities. Thank you for correcting me. I will say being facetious was not my intent, but I nonetheless deserve the insult for my failures.
@@pion137 The important thing here is that you learned a valuable lesson in RUclips etiquette. Good luck with your sponsorships, future earnings and endeavors. 😆
Flip it (put your clutch on pedal side, not the wheel side) and use electro magents instead of permanent magnents. That way you can harvest energy while braking and increase your magnetism when you're applying power.
I love how you had an idea and made it reality to test it. That's the sort of real-world findings that could prove to be useful for all kinds of applications that may even be totally unrelated to your project. I bet someone out there will see this and get inspired to try this in something else
But this is already in use. It's basically how an old school speedometer works. A spring loaded aluminium cup is driven by a magnet inside, that's it. Also many old record players use magnets to fine tune the speed (eddy current brake).
HI Tom, first of all this video is great. Secondly, I strongly suggest you to repeat the experiment trying to reduce the air gap. The first thing you shuld do is mounting the magnets with a plate of steel on the outside, the steel will increase the conductance of the magnetic flux increasing the flux in the copper plate (this steel plate would also act as a shield between the chain and the magnets). Other improvement could be to mount the magnets between two copper plates, that would also increase the efficiency of the magnets, I estimate that doing that would give you the same torque with half of the magnets. The hard part is mounting the attachment. On the mechanical side, it could be interesting adding a stage to the transmition in order to multiply the speed of the magnets.
Just a brainstorm. The reason for the heat is because of the electrical resistance of the copper disk. Also, keep in mind that electrons move on the surface of conductive metals. By thinning the copper disk and silver plating the copper (at least where the magnets are) we can reduce the heat.
@@TheAmity adding to your brainstorm, I'm not sure if skin effect takes place in this particular case. But if it is the case, making the disk with thinner layers of copper isolated between them would also improve the efficiency of the metal conduction. Because it would have more skins to induce current.
@@grannqnito I appreciate your kind reply. There are lots of factors involved in Tom's great project that are not easy to discuss/share in this way. For example: at the introduction of the video Tom showed us the moving magnet inside a copper tube (one the most efficient because of the circular shape of the tube). The current distribution inside copper dist is very chaotic/inefficient (in my opinion), but using a copper tube instead will be more efficient (in my opinion, again). I wish I could attach some images/sketches to explain my suggestion/theory about implementing it. I enjoy the exchange of ideas/thoughts in the frame of logic, it opens the mind to new doors.
I would also think that significant spinning mass could be saved by skeletonizing the copper plate. Combining with your 2 plates idea, that could end up with less weight for near double the effect and spreading heat out. That could in turn allow it to be smaller diameter and less magnets, further reducing spinning mass.
You could solve the magnets attracting to the chain and spokes using Mu Metal. In mechanical hard drives, they are thick and attach to the magnets, but completely prevent the magnetic field from progressing further, and help to contain the field in the gap where the voice coil moves the heads in and out of the platters.
***Change the design slightly - put slots in the back magnet wheel so the magnets can move back and forth based on RPM maybe you would get some variability in torque base on how much centrifical force the wheel is applying the magnets since the RPM would would be larger when they are at the bottom of the slot and lower at the top of the slot.
A halbach array instead of a simple N-S magnet setup would would make the effect stronger for the same size/number of magnets. Besides, that, pretty cool!
That's correct but he will have to either have to cube magnets with the same field strength or he will have to increase the gap between the magnets chains and spoke for it to work
@quinor I'm not talking about the sookes and chains attracting to the magnets I'm saying that the magnets he us using will physically collide with the chains
Although you may not see this as a success, there's some great ideas here. You learned so much through it also. I think you will come up with practical solutions in the future. It's great that you have the mind and the tools to create what you envision. Great work.
Hello! I'm master mechanic with experience in 3D-Printing and CAD, so I watched this video enthusiastic. I'm really sad, the efficiency is so poor. But - if You don't test it, You didn't know it. I'm sure, You had fun to do it. Great work!
I'm so glad to see this channel doing well. It started out with such goofy ideas but Tom has kept at it and it and always comes back with interesting ideas and very good executions. Bravo mate
I know this is a bit old but at 5:25, you said you cant machine that thread but you have a CNC router. Why couldn't you thread mill it? Does your router not have true simultaneous 3 axis control to be able to do helical moves?
About 35 years ago, Schwinn Bicycle Co. had a frame you could mount your bike to that had your rear wheel run on a roller that was tied to an almost identical arrangement. You could vary the position of the magnets in the assembly by turning a knob.
Just thought I'd drop a line to say that I find this type of thing absolutely fascinating.. such great work and thoroughly entertaining! Keep it up my friend!
This reminds me a lot of a torque converter in a conventional automatic transmission for an automobile. You could take this one step further, as the auto manufacturers did, and have the option to lock the torque convert up so that there are no frictional losses between the copper disc and the magnetic drive.
While it was completely useless against a conventional direct chain drive, it was one heck of an experiment! Probably one of the the most interesting scientific/engineering experiments on RUclips! Love your videos!😄
Really like how you put the different tests with different variables are shown alongsude each other in real time. It really helps visualise the relationship between the variables, like a real life graph. 👏👏
Every time you have some different ideas, we see it implemented within seconds in the video. As an engineer, I know the pain anxiety of the challenge to go through implementing ,and the excitement during the test, and of course the joy when the idea works.
Testing out theory vs. real practical application. He makes excellent points. The next thing to do is to figure out a force needed to move the bicycle up to 20-25 mph to justify all of the benefits of the gear-less system. My guess is that some form of E-propulsion needs to be added to assist the cyclist in attaining the speed they need to enjoy the ride while at the same time adding in more resistance which would assist in the braking function. As he showed in the video, the braking system needs help too. With more force on the chain to back sprocket, more resistance is built up and maybe that would solve the braking issue. But in conclusion, I guess this is one of those "Good idea but not quite there yet," videos. Keep up the good work, Tom and we all are interested in seeing if you can get this design to be fully functional for the rest of us. Looks like a good concept for a bicycle company to use. Maybe hold off on showing your final "By God, it works!" version and patent your concept, instead and make some cash on this idea. THUMBSUP
@@matsuz100 patents only prove said person invented said thing. He can demonstrate that he came up with said idea here 1st icluding the dates of all the footage he has used. But from watching all he has done I think with more work he is onto something great hopefully no toerag will steal his idea. Finally he has inspired me, period
You're amazing to tackle and command this new concept! I wasn't surprised when the plastic wheel gear broke. There would be a lot of torque on that part to cause sheer. More MAG power and Innovation to you!
I don’t know if regenerative break is available for e bikes but this system can make it possible to recharge your e bike battery during down hill. It is quite interesting and love to see a design like this.
When I've thought about doing something similar, I was going to mount the magnets to the rim of the rear wheel. My idea was to have a series of solenoids adjacent to the rim to act as drivers or breaks, with electricity from a pedal-powered generator, and a capacitor for a bit of breaking storage. It would be cool to see that in action, just in case you haven't done enough electric bike videos :p
Even dull looking copper is a great reflector of infrared light, like a mirror would do for visible light. It has a very low emissivity so you would have to stick some tape to it to measure its temperature with a thermal camera or you will just read the temperature of the things its reflecting. Interesting video. I was about to experiment with some magnetic coupling myself and was wondering about the alternating magnet orientation :)
I kept a protective plastic film on the backside of the copper disc for that exact reason (notice the thermal camera shot is from the other side of the wheel vs regular camera shots). When aiming the camera at the exposed copper side, it just showed the temperature of the reflection.
Tom, your simply unmatched ability to logically apply principles of analytic geometry, test and evaluation, and the linking of the governing physics to mathematical expression is a masterclass that I wish I had in my undergraduate aerospace engineering degree program. I want you to know that your channel is more valuable than most engineering curriculum due to your ability to efficiently distill and demonstrate the power of iterative design for real-world applications; your content is the truest expression of what it means to be an engineer. Keep up the stellar content!
I love your bike-related videos! I'm currently trying to understand basic mtn bike geo, and am envisioning an experiment that I don't materials or experience to do myself: Setup: Inverted pendulum on a car with adjustable axle placement, something to stabilize the pendulum (motor?), and a course with undulations to acceleration/decel and bumps to roll over. Test objective: find the ideal axle placement that allows for the most stable pendulum, to the point minimal overall work is needed to correct/stabilize it over the course. Expectations: widest wheelbase that can still clear the undulations, with the pendulum centered towards the rear, with maybe a 60:40 weight distro, on the rear may perform the best. Lesson: be better informed, to help filter through bikes that may not be so good based on bike geo (ie. beach cruiser bikes, that have cranks in the middle between the axles, disguised as mtn bikes)
Regarding "gears" you could use some kind of centrifugal force mechanism, that pushes counterweights out when you pedal faster, pulling the magnets in. Having the magnets closer to the rim will give you some leverage allowing for a lower "gear" when pedaling more slowly. This might be difficult to build and also difficult to control when riding, but on paper it should work
@@TomStantonEngineering first of all: nice work! To give you a hint about the behavior of your system, it is the principle of an asynchronous machine with a so called squirrel cage. That's, I guess you already know it, the most popular electric motor you find in industrial applications. The amount of torque depends on the slip, means the relative difference in speed between the wheel-disc an the magnets. Theres a formula called "kloss equation". You will find curves that show you a maximum of torque depending on the so called slip. If you're more interested, we can dive deeper, since I worked at an institute for electric machines. Regards, Robin
@@TomStantonEngineering - some electric machines can CHANGE their coupling level - because they have electric magnets instead of permanent magnets. this means if you power the magnets down, you will get a real free wheel. also the slip can bei tuned to your needs. - have fun!
@@TomStantonEngineering thanx for clearing t5hat up I was thinking that throughout the video whole thing was truely inspiring you have a new sub! whats next? an improvement or moving on cant wait for either?
13:19 Have you also tested freewheel and flywheel and thicker copper disc? And on the backside of magnets you need normally steelplates, to better feed the flux, and you will not have problems with magnetizing of chain.
Great video Tom! Love the in depth testing you did. Although I really wanted you to spin the wheel in the other direction to try and stop the bike quicker. I assume spinning it faster in the other direction would act as a better brake than just the magnetic friction.
I think you have one of the best engineering explanation videos on the internet. You always come up with some great crazy idea and introduce and explain bunch of ideas along the way. I'm super excited every time you upload!
I guess the next step is to build a superconductor clutch to avoid the heat issues. That'll totally work.
A boring fixed gear can do that, too
Nah, he should just invent a room temperature superconductor instead. Seems simpler.
A supercunductor plate would cause it to be locked together lol. It would be almost impossible to slip it. That's essentially how magnetic levitation works.
@@rubiconnn but then it could be controlled. Connecting a grounded resistor to the superconducting plate would disturb the eddy currents, and provide momentary 100% slip. You could switch it on and off PWM style to tightly control slip.
Now we just need room temeprature supeconductor. :(
Yeah that would induce instantaneous eddy currents of such proportion to effectively bolt it together, it would be an expensive, weighty and very cold cog.
I'm a physics professor and this whole project is incredible! That's one whole chapter of the textbook in a single short video!
That's why I regularly substitute lectures with RUclips videos - sometimes there is incredible stuff to find, that saves the student (me) hours of agony and self hatred. Hehe.
Idk what these people do differently, maybe it's because they're closer to the point where they didn't understand it themselves than most professors are, but they sometimes have an incredible efficient way of teaching. (Helped me most with theoretical physics stuff)
You are not good at physics. Because you don't understand the science behind math, electricity, chemistry and biology.
You are not a professor.
You are just on papers, but the reality is painful. If my kids will have a teacher like you, I will remove my kids from the school.
You are a shame for all the italian schools and physics and science departments.
@@braindecay9477 Personally I suspect it's just numbers. If there's hundreds of youtube videos explaining an idea, you're only likely to see the best ones, and the many many terrible videos just drop into obscurity.
Whereas with your actual college course it's unlikely you have all the best professors for every subject.
Although that does create an interesting idea. Imagine if you had access to lectures from hundreds of professors worldwide and your tuition went to the ones you watched the most.
@@peterhoulihan9766 But how would that help to promote the woke communist global takeover?
Well I don't think most physics teachers have a small team, a budget that allows for cnc machining and 3d printing custom parts, and weeks/months to dedicate to creating a single 30 minute lesson (when would they do their marking?)
The positioning of the weights at 7:44 is such a pleasing real-world representation of a log graph, I love it
might be a hyperbola
i tought the same !!! cool
@@canteatpi or a root of some power. I think it's more likely to be a square root graph, due to the powers in the formulas for kinetic energy
@@mikhail_from_afar ты говоришь по русски? я учус, но это очень трудный язык :)
@@datbubby учусь*
"...and this result wasn't linear" @7:38 Beautiful visualization. Nicely Done!
oh yes, one immediately gets it! Incredible communication
The side by side comparisons are astonishing, it’s amazing to visualise the different behaviours induced by different configurations of magnets and weights
True. I just wished he had filmed them with his infrared camera, so that we also see the amount of heat loss
@@MrGustavier yeah true
@@MrGustavierYeah that would probably be really interesting, but I still think it’s good as it is of course
Tom is brilliant, I wouldn't be surprised at all if the heat generation turns out to be a huge positive for future project potential, surely this magnetic contactless set up could harness all sorts of free incidental energy
He could've used an off the shelf thread on 6 bolt brake adaptor for $10 instead of printing such a disc
As a bicycle mechanic over in Germany I gotta say, I really love your bike related videos. They give me great aspiration, sadly I lack the funding to copy your concepts for my own fun. But they make great talk in the break room!
In another life, I was a bike mechanic too. I probably enjoy as much these videos as you. Now that I’m doing more software and hardware, after building a few robots, it tickles me to try and build a braking system idea I had a long time ago!
as a bike mechanic in Germany, do you work on Rohloffs or other internal gearhubs. How do you like them? If this magnetic clutch/gear works, it would be fantastic!
I'm wondering if being able to vary the strength of the magnets (by making them tiny electromagnets) would make it a practical device. Sort of like gearing through magnetism. Probably not, but it's so tantalizingly almost useful.
By having Flux collector on each magnet of Faris metal you could greatly increase the magnetic strength of each magnet in the desired direction. If done correctly it could reduce the attraction to the chain.
Why not start a youtube channel with bike experimentation? It probably will pay for itself if done right... viel Glück!
The alternating magnets for stronger eddy currents was a great idea! You might want to look into the Halbach Array (a specific way of alternating magnets) that makes the field strength even higher. I think it might perform better than only alternating the magnets.
Exactly what I was Thinking.
Also can't he put a steel plate on one side of the array to cancel the magnetic field so he won't have issues with the chain and spokes?
Also it makes magnetic field much stronger on one side (the clutch side) than on the other side (the chain side).
@@oodmboo If he made the diameter of the disks bigger he could fit more magnets in to give him the torque he needs to go uphill and it would also solve the spoke problem since the spokes are already sloped away from the magnets further out.
Might run into torque issues breaking the disc though.
the steel plate (ie completing the magnetic circuit) is better than a halbach array unless you are extremely concerned with size and weight
@@5naxalotl Rotational inertia is certainly important, though I don't know how much.
I was very dubious at the start, thinking, “oh, yeah, another magnets perpetual motion scam”. . . but no. I learned a lot from this. . . an honest presentation. Nobody’s going to win the Tour de France with this setup (especially me, a 79-year old time triallist)😊
Well done, sir!
you are a very cool looking 79 year old.
Those calculations with the dropping weight videos were awesome, such an excellent visualization.that section was great!
oh yeah, you can literally see the non linear curve which was beautiful
This is the stuff that science is made of!
No wonder white men created all the modern science and tech
As a retired engineer who cycles a lot, I enjoyed this immensely!
@H K And more expense! It could be a government mandate!
The comparison shots of the falling weights was incredibly well done
Hmm... but copper is three times heavier than aluminum. If we consider that in the equation...(brain stops)
Right? It literally generated the graph.
@@operatorchakkoty4257 It makes sense on why it *looks* like a graph ... but then still "holy-shit" nevertheless
I loved how you could visually see the logarithmic, non-linear curve in that one test.
Is there a good way to redo this experiment with electromagnets and then be able to variable control the strength of the clutch? Also with electromagnetism you could possibly also have the brake do regenerative braking to recharge the electric battery. Would be a great way to continue this project into a more usuable concept. Im not sure the specifics on how it would work, but would love to see it built. Thanks for the video tom and hope you make some more videos soon.
Tom again shows us not only how clever and creative he is, but also just how great RUclips can be with the right content providers!
Totally agree, RUclips at it’s best.
If my damned AWFUL home feed could learn this... I would be sooooo happy.
^^ I made a new account and seeded it with a Playlist of content types that I wanted and now my algorithm is much better than the old account. Probably a good idea to do this every few years to get a fresh look.
@@DerrickBommarito replies are broken
you are very correct
I think you may have missed a trick. Putting an iron backing plate on both back sides of the magnets (ie facing opposite the copper disc) would give you two additional advantages. One being the flux would be more constrained and not grab the chain/spokes and the field facing the copper disc would be more intense. However the heat due to loss will definitely be more severe when the clutch starts slipping and will equally affect the magnets, which in your case, due to their size might have been a bit cooked too, but cooled faster due to less thermal mass. But in theory, the increase in efficiency would mean less slipping.
Another factor is that neodymium magnets permanently lose their magnetism when heated to approximately 85deg C, which is why when these types of clutches are used in industrial applications, there is usually a significant liquid cooling system that either flows through the clutch components, or the clutch is immersed in it.
They are very precise and consistent (repeatable) clutch designs that can absorb massive dynamic changes in force, so they are very useful in other applications, where longevity and smoothness are more important than efficiency in the force transfer. They are also used as brakes and dampers for similar reasons and also have more traditional lockup mechanisms and or clutches for greater efficiency when output (or input in the case of braking) has reached a certain speed.
Obviously these are stupid expensive, mostly due to materials, proper matching of the specifications, and definitely being customised for the application, not to mention bulky, but sometimes they are worth it, to solve particularly difficult problems where traditional force coupling mechanisms don’t work as well. Anyway, sorry for being “that guy” at the party, great video and demonstration of a very useful and niche device!
I think you're the guy we very much needed on this party. Thank you.
Chain sticking is solved by using a rubber belt
Tom, this response is on the money. Ferrous materials will provide a much lower magnetic impedance than air, increasing the magnetic flux density experienced by the copper. So putting some of the outside faces of the magnet groups will improve performance.
Again, on the money; watch out for heating and ideally turn that ferrous material into a heatsink for the magnets.
Finally, milling a shallow pattern into the copper to sort of turn it into a centrifugal fan, (increasing air turbulence and heat transfer) may also extend the operating envelope.
Mind you, it will always be lossy. Maybe it's more of a mobile cardio machine?
@@pchandle c'mon peleton!
Electro mechatronics engineer here and were about to write pretty mich the same thing! However I disagree on the heat part... Yes the magnets suffer from higher temperatures but the heat is generated in the disk and not in the magnets. The suggested ferromagnetic parts to close the magnetic flux would alsobserve as additional radiators for the magnets to get rid of heat.
Your meticulous research and trials of materials and forces is truly impressive. Then to advise us that it didn't work as you had hoped shows your humility. Thanks for sharing this whole story.
The answer is seen in electromobile vehicles- Alternating current (in motor wire-windings) is far more efficient than permanent magnets only (which are also present in many EV motors). Also stopping power in EV regenerative/recuperative braking had same weakness as described in this video. But - with alternating current oposing the magnet rotation, it can be managed to fullstop in most current EV vehicles.
Which translate to even not using normal friction brakes/pads at all = rusting.
So this research is not completely wasted- it just needs to simulate EV motor = induce some current in copper disc (made from thousands of copper wires, insulated of course). And electronics with variable frequency of alternating current, made by using Gate-transistors.
Of course it is not needed as you can buy such a bicycle now, but- exactly the same proces they do in Tesla, Mercedes factories/labs.
I would suggest utilizing the Eddy currents to store energy so it can act as an electric bike when needed. The heat is generated from those unutilized currents. That would solve your inefficiency.
Kind of like regenerative braking? Using the brake force to store some "losses", and of course, that would help it brake more efficiently, as well (especially at back pedal)
Using superconductors to eliminate ohmic losses?
This channel was new to me. I was blown away by the concept, quality of the build, quality of the experimentation, and the quality of the video production. You, Sir, are really good at this!
He's a mechanical engineer
Completely agreed, very impressive testing and engineering
Check his railgun project
There's another guy, James Bruton, who does very similar experiments, uses 3D printers, uses a very similar methodology AND sounds like he is from the same part of the world as Tom here. I think they should work together on a project! For example: ruclips.net/video/6YG8CsCE0WM/видео.html
Seems like youtube as a whole is new to you...
Hey that's pretty neat to learn about the alternating polarity creating a greater resistance. I didn't think of that. You could print a little cube grid that holds multiple magnets with opposing fields and probably get a much more impressive slow down when dropping it down a pipe.
Seeing your comments across a few different channels at the moment. Dont you have videos to make!!😊
@@UncleChopChop22 have and owe are two different words as per the dictionary.
If you thought about it for a minute, you would know this. Here's an important thought experiment: what if you replaced the ring of alternating magnets with an actual machined ring neodymium magnet concentric with the axle? How much torque would be transferred?
Zero. The answer is zero. It would spin freely.
Eddy currents form when there's a *change* in magnetic field, not just whenever there's a magnetic field. So the more changes there are, the more eddy currents form. The only limiting factor is when the magnets get so small that the changes in magnetic field don't bridge the gap from the magnets to the conductor.
Maybe the printable magnet company featured on SmarterEveryDay could create a tiny alternating pattern ruclips.net/video/IANBoybVApQ/видео.html
@@Squancherino You people do understand that the efficiency asymptote this thing is approaching with more effective magnetic fields is identical to just gluing the two plates together, correct? There is literally zero benefit to this clutch? I feel like everyone is missing this fundamental concept.
Making the copper plate thicker would reduce the number of magnets needed by decreasing the resistance for the eddy currents. And as other people have commented mounting the magnets in a steel mount would also improve the performance by helping to concentrate the flux. Similar just for kicks project would be to try to convert this into a homopolar motor regenerative braking setup with some big capacitors.
Also making the plates from a larger diameter plate would result in less input speed equal to the increase in primary drive sprocket getting that magical speed differential is probably key to better transmission and more heat dissipation
@@Neil-z2oBring on the copper wheel rim! About as little slip as fixed gear mechanical at maybe 4x the weight! Would be an interesting test.
There is a bicycle trainer device called the Kinetic that has used this principle for decades. The resistance unit is hydraulic, that has a sealed chamber to prevent leaking. It’s hard to seal around a shaft, so they drive an impeller inside the sealed chamber with a magnetic clutch. My trainer is decades old still works great and no leaks.
One factor you seem to have overlooked is that if you want higher braking at low speed you could always just pedal backwards and increase the effective relative speed of the wheel vs the magnets. I do otherwise agree with people's suggestions of reducing the amount of copper used. I'd also suggest, from my limited electrical engineering knowledge, that you cut air gaps between sections of the copper, as that should cause greater eddy currents since the air will act as a dilectric and theoretically cause increased resistance. Will admit I'm unsure if that'd improve the effective coupling overall, but it seems like something that would at least have an impact.
Hi Tom
The checkerboard is only useful if you also want drag in the left-right direction.; generally the magnet diameter should be greater than the gap between facing magnets.
More importantly, please look into "back irons" - these will easily improve the effectiveness by 2x or 3x and shall also eliminate the problem of the chain sticking to the magnets :)
Yes! I think this would probably double the performance at least. Mumetal is ideally suited for the job (which is why they use it in hard drive voice coils)
Would it not work better if there were magnets distributed around the disc ?
(perhaps at pitch centres corresponding to say 9/10ths of the pitch of magnets, to get a sort of vernier effect).
I guess the poles on the frame would want to be opposite polarity to those on the rotating disc. You'd want magnets both sides of the disc, to balance out the axial forces.
@@Gottenhimfella Quite a few drawbacks to your scheme - The damping (i.e. conversion of kinetic energy to heat) happens in the conductor, not in the magnet. A magnet shall store energy as potential energy (and then is mire like to demagnetize too, but that is a different story). So, to convert KE to heat, a conductive disc is essential. The added moving magnets shall add inertia to the rotor (non-issue in a bicycle, agreed) Second issue is that of axial (parallel to the axle of the wheel) force - rare-earth magnets of this size pull hard - a symmetric construction with two sets of fixed magnets and one moving conductor has no axial forces, and hence can be thin and slim.. to work-around this, perhaps 8/10th or 7/10th would be better. The third issue is cogging. Even with the Vernier, you would feel some. The advantage in your scheme (if I understand it correctly) is that you eliminate the air-gap on one side of the damper. The disadvantages that you have to pay as a price are, imo, not worthwhile (at least with my understanding of your described concept. Feel free to 3-d print a holder with 7-magnets and 10-magnets arranged in a circle and try twisting them against one another :) (without a conductor, it will feel more like a detent than a damper)
Magnetic coupling is very useful for underwater applications, where you want to disconnect the propeller from the internal electronics. Back when I was in highschool, we built an autonomous underwater vehicle and faced a real problem with isolating the propeller's entrance.
But don't the magnets need to be really close to the disc for reasonably efficient power transfer, so if you have to put the waterproof bit of the boat/vehicle between the two then that's quite a lot of spacing you didn't want. How well does it work across 3mm of fibreglass (or whatever is sufficient to keep the water/pressure out).
@@xxwookeyYou can design for the gap with larger magnets or different materials that don't block the field as much.
These days there is no need for a watertight prop shaft as brushless motors perform quite happily in water and can be outside of the submersible.
@@robwilton9539 *barnacles grow on your windings*
@@xxwookeyIf you're worried about pressure you could fill the engine room with another liquid and seal it off.
I like how you're talking with simple language and not just scientific things so everyone could understand you
Thanks man
What happens if you pedal backwards? Would that provide more braking force? How would the addition of an electrical current affect the resistance?
Great videos! I really enjoy watching and learning such interesting concepts!
One of his tests demonstrates that the torque generated was proportional to the difference in RPM between the disc and the magnets, so yes, pedaling backward would increase this difference in speeds, and therefore produce more braking torque.
The other question is interesting. The eddy currents that the magnets induce in the copper disc flow in a ring around the magnets, lagging behind the magnets because it takes some time for the current to die off once it's induced into a particular path. This is really how the torque is created - the ring of current induced by the magnets produces an opposite magnetic flux to that of the magnets, that's constantly trying to align itself with the magnets, so any rotation of the disc produces a "back torque" that opposes the motion. If you were to fit carbon brushes either ahead of or behind the magnets, current passed through the disc through these brushes will also produce a torque for similar reasons. You will have created a DC motor, but this would be very inefficient because the current you apply to the brushes would not just flow through the copper directly between the brushes, but also though many other paths that would not produce usable work. This could be improved by cutting slots radially at intervals around the disc, between the brushes, which would reduce the undesired currents without affecting the intended current path, but now you're getting closer to a conventional commutated DC motor. Which sounds like something interesting. However, if you look up radial flux brushless DC motor, you will find that this is very close to what is already being used for low-speed, high torque brushless motors.
Pedaling backwards does increase the braking resistance, because it means the sprocket RPM becomes 'negative' and the net RPM difference becomes larger.
Regarding electrical current, the current in the disc is not DC but it's a localized AC current which moves along with the magnet's rotation. To get the disc to spin using electrical current, you need to apply a rotating magnetic field through a set of coils. In his experiment, the magnets are replacing the pole pairs of a motor.
thats what i was asking myself the whole vid too😭
@BrightBlueJim Thanks for the response. I'm not an engineer and am not up to speed on the theory of DC motors. I know enough about electricity to be dangerous. My crude thought process was that an electrical current might increase the amount of torque that is being applied to the wheel from pedaling and provide a better braking action. Thanks again!
@@BrightBlueJim The homopolar generator designed by Michael Faraday was a similar design as well, very cool seeing how this is basically that but with no wires connected to it.
I think you calculated based on cruising power rather than the power needed to accelerate/decelerate.
Really interesting build!
Also:
If you look at induction motor rotor design you see that they commonly have slots.
Part of the reason for these is to reduce the reach of eddy currents that cause those heating losses you see.
So cutting a bunch of wedge-slots in the copper disk would probably improve performance a lot
acceleration power is lower if acceleration is slow
@Blox117 right. And if you design the magnetic coupling to handle the cruise power, the acceleration is limited to what that power can provide
It's not a big deal, but it does show on the real-world performance tests
@@argledotorg those Eddy currents are a feature here, not a bug. It won't function without.
@@Azeazezar if they travel too far, they generate heat rather than force.
This is an induction motor stretched out onto a plane, with the moving electric fields provided by physically driven permanent magnets instead of AC/stepper controller driven electromagnets.
It's an elegant and clever device, for certain.
In home exercise bikes, a magnetic brake is sometimes used in the form of a set of fixed permanent magnets (or electric magnets in expensive devices), and a perforated metal disk (similar to an aluminum alloy) that rotates through an upshift pedals. The adjustment of the braking force is regulated by changing the distance of the magnets from the rotating disc. Excess heat is dissipated from the disk into the air by means of a small impeller with blades on the disk shaft. Thus, it turns out to achieve a fairly wide range of loads (from 50 watts to 1.5 kW) with modest dimensions of the device.
It's fine for a brake, where you are trying to convert energy to heat. That's not what you want for a transmission, where you want to waste zero.
Its also used for high speed trains to stop it from a high speed. Its a huge magnet thats dtops down to like a millimeter above the rail. de.m.wikipedia.org/wiki/Magnetschienenbremse
@@jonkess2768 Not just on high-speed trains. Old trams had an electromagnet braking system on the rails. But in both cases the rail is steel, and permanent magnetism is used; in the case of aluminum, a different principle of operation is used, due to the induction of an EMF in a short-circuited circuit, the so-called “Foucault current” or eddy currents, which occurs in a conductor in the form of an aluminum disk its own magnetic field arises, which slows it down. By the way, the same problem occurs in speakers, which reduces the output at high frequencies due to increased electromagnetic induction, and to compensate for this phenomenon, copper short-circuited caps are used on the core of the magnetic system.
I think the best use of this sort of thing would be if you had a normal chain drive, but you could engage and disengage it like caliper brakes for coasting down really long and/or steep hills. Much quieter and no brake pads to wear out. Also have conventional brakes for emergency stops.
It's always so mesmerizing to witness eddy currents. I was playing with magnets and a copper pipe a while back and it's so so interesting to see it happen. The clutch idea is interesting, I could see this being useful in some kind of application that may get sudden changes of resistance, and it would save the output shaft of the motor. Rollercoaster brakes also work similarly to this.
Do not forget that Trains are fitted with induction breaks. No wear, and at high speeds to stationairy rails incredibly effective.
Roller coasters use this for emergency brakes.(obviously using a secondary brake so the train comes to a complete stop)
Even after 3 years of engineering school, I still learn so much from your channel. Great videos!
You didn't learn how electric motors work in engineering school?
@@trentvlak To preserve your remaining dignity, I suggest you stop speaking now.
@@bagel_deficient explain
From the perspective of a computer guy, on a value-per-hour basis, school is outpaced by deliberately playing around, especially after a certain point
quit paying that place you call a school
Tom, I really like your focus on the subject of your videos. Been watching you for years and as many other channels over-hype, fast-cut, force jokes, etc... you've stayed one of my favorites. I can watch you when having a slight headache and it's not too much but rather interesting and calming. Also, good on you to commit to all your interesting ideas, figure out if something would work and show it. You test so many things a lot of people probably have wondered about but no one has seriously tried yet, let alone shown it to the world.
Please keep being you, lovely to watch always!
I noticed that this is much the same as the way my exercise bike works. There are two belt-and-pulley setups that spin an aluminium disc between a couple of magnets. The resistance is varied by moving the magnets in or out. And yes, my efforts go into making the disc get hot!
There are row machines with similar magnet setups too.
The purpose of your exercise bike is to give you exercise - to make you work, by resisting your pedaling. I'm sure you will notice that the disk between the magnets warms up, because your work being used to generate heat. In Tom Stanton's case, however, the desire was to convert the work into distance. So the desired outcome of the two machines is opposite, one to waste your effort as heat; the other to use your effort to go so0mewhere - but the actual outcome is much the same. Work produces heat. Your exercise machine uses *_all_* your work for heat generation; Tom's machine gives some distance travelled, but it is limited by its inefficiency, which produced heat.
@@DownhillAllTheWay i agree totally. Which was not difficult because you basically told nothing new.
It is basic logic.
IF your exercise machine was using your work to give you some distance it would become a problem because you need a large room to house it in.
Btw, you could just take a bike outside if you want some distance travelled while you work.
The whole idea of an exercise bike is that it is stationary and doesnt travel any distance.
SO by that way of thinking i would say it is kinda pretty logic what you explained.
And, some would then be very rude and say: Jeez, thanks Sherlock.
But i wont.
I just think it.
>:)
(yeah, i am a stupid dutch guy, so i blame it on that)
@@DownhillAllTheWay o damn, sorry, i forgot to add this but it has to be added.
The first part you typed:
The purpose of your exercise bike is to give you exercise.
I forgot to add it but it should be somewhere in the start of my comment to make it more clear why i would think: Jeez, thanks Sherlock.
>:)
Just a joke sir, just a joke.
@@bertjesklotepino Hi there! Don't worry, I took it as a joke. I was commenting on the video - not trying to explain it - but I'm sure you understood the intent of my comment. All of the best to you, Sir!
Two points I'd have tested; 1. how much does it slow you if you pedal backwards? 2. what does it do for controlling speed when going down a hill (something steep enough to normally require braking)? Interesting as always! 👍👍
Add 80w of power and no need to pedal?
I was going to ask the same question. Thanks!
It looks to me like the rear sprocket has a ratchet, so pedalling backwards wouldn't turn the magnets in reverse. I think.
@@ParaBellum2024 actually on rear sprocketed wheels you *can* go backwards. its just VERY slow, if your not in a BMX park or on a slope.
Backwards rotation will heat copper disk to huge temperature and it just start to melt this plastic)
I am never more excited then when i see a video from Tom. The step by step research to prototype of an idea is unmatched in my opinion. Truly top notch content!
I feel like you could put this in a car to assist the normal clutch and reduce clutch wear. Especially the dual clutch ones would greatly benefit from this.
would be cool to see how pedalling backwards while moving forwards would effect the braking power.
Yeah thought the same. Does not make any difference just pedalling backwards when trying to brake?
It will make a big difference. The speed of the magnets and copper disc relative to each other determines how much force they exert on each other. So at higher speed he exerts a lot of effort just to hold the pedals still, but at lower speed it should be possible to pedal backwards and therefore create enough force at the wheel to stop in a reasonable distance.
I mean the force was so strong it was basicly pushing his feet forward. Maybe peddling backwards wouldn't even be possible at higher speeds.
@@jackbauer2698 if you look into the world of fixed gear cycling, you find that people can break the traction of the rear tire and lock it by pulling up on the straps that they install on the pedals. The only thing preventing you from pedaling backwards is the traction of the rear tire.
It would either be enough resistance to break something on the bike, or open a rift in the fabric of reality...
You could try mounting the magnets as a halbach array, it's used to point most of the magnetic field in a single direction meaning you'd get more Eddy currents and less chain sticking!
And get a stainless steel chain And a "spring toothed?" One way gear on the front sprocket for coasting AND a way to close and lengthen the gap between the magnets and the copper disk for gearing AAANND enclose the magnets to separate the road environment because they'll clog themselves with iron dust.....oh and some hand brakes for stopping. By the way, your copper disks will warp from the heat so make them easily exchangeable.
It would have got all the flux on the side of the copper disc, which might have prevented the magnets from sticking to the chain.
Do it, would be a nice-follow up video. Maybe easier with the cubed magnets than than the cylindrical.
If you go halbach the distance between mags and copper becomes more accurate(making a gear ratio situation more difficult to "tune in") so heat and warp aren't worth achievement of gearing. Gears, cogs and chains beat you damn engineer "thinkers" out every(almost) time. You might try focusing more simple, less complicated.
What about a gap magnet?
You had an idea and you concisely show how you went about implementing it and the methods you use. Thank you Tom for inspiring the younglings, I have no doubt we'll get some amazing innovations in the future, influenced by your ability to educate. Even though I pay little attention to the numbers and equations I still end up feeling slightly smarter from watching your videos.
Remember that the Lord Jesus Christ died on a cross for you because He loves you so much. He then rose up from the dead three days later
The Ten Commandments are called the moral law, (most of us are lying thieving blasphemous adulterer at heart and deserve hell) you and I broke the law, Jesus paid the fine. That’s what happened on that cross.
By believing that Jesus died on the cross and rose up from the dead 3 days later and not just confessing your sin, but also repenting of all sin you have done and putting all your trust in Him in prayer, He will grant you everlasting life as a free Gift
@@dove3853 Bit off topic mate.
@@Billybobble1 That bible bashing fool didn't even knock on your door before randomly spouting his completely irrelevant BS at you. Pretty damned rude I'd say.
Completely agree with your assessment and way of seeing this and others of his videos. There's so much I'll never understand but, I still learn from this sort of thing. One question I had he did answer was, whether the resistance was converted to heat or not. If it hadn't, it could have opened up a few more interesting possible uses like speed control of things without wear, obviously but, heat can be a problem too and a non heat generating device could be extremely useful in some situations. Still very interesting stuff though.
@@dove3853 Tell Jesus I'm not interested
From an engineering standpoint, I see two obvious improvements.
Although copper is a better conductor than aluminum, aluminum is stronger and better for transferring work. Use aluminum instead.
For the magnets interfering with the chain, modify the sprocket to cross the whole axle and put the magnets on the other side.
As for coasting, modify the clutch so that the bike rolls freely even if the sprocket and aluminum plate are stopped. I wouldn't even try adding a magnetic braking system to this setup because that would transfer a ton of momentum to a small part (the sprocket area) which would wear out the sprocket very fast.
If you wanted magnetic braking I would suggest a secondary aluminum plate on the chain side of the wheel. Make it fixed so it moves with the wheel at all times. Then have magnets slide in and out from a fixed position on the bike, probably under the seat and well away from the chain.
I'd love to see a return to this experiment with more designs and maybe some alterations with additional parts to see if this could be further built on as a viable drive method. The concept seems really awesome, and I'm sure there's got to be some utility in this somewhere.
It could be the basis for a new kind of automatic transmission in cars. Instead of an epicyclic gearbox driven by fluid, pressure and friction with wet clutches and bands, it's magnets!!! Clutches, bands and the hydraulic fluid in an automatic transmission will wear down over time, but magnets will probably last a lot longer.
The magnets could be turned on and off electronically (they would be electromagnets, not permanent ones). Instead of clutch packs being pushed together by a piston, it's a current turning on electromagnets to make two discs lock together. The current would replace fluid going through solenoid valves in a valve body.
I have an idea for you mate. You could have a variable gearing effect by mounting the magnet cages attached to radially mounted springs. Mill slots in the disc around where the magnets sit under spring tension to reduce the eddy currents formed there.
Use the centripedal acceleration to have them push outwards from centre and thus engage with the intact portion of disc on the perimeter at an RPM detemined by the spring rate. You'll have basically combined the centrifugal clutch with the magnetic drive.
up
I agree... He definitely needs to make a version 2, with some kind of centripetal action, because he wants a CVT. I'm not clear on whether the low RPM engagement should be at the outermost diameter of the copper disc, or the innermost, for the proper torque multiplication (I think it should be on the outermost at 0 RPM and move towards the center as wheel speed increases).
Great work! I think this is essentially an induction motor. What helps the induction motor work more efficiently will help this clutch as well, e.g. adding slots to the disk to limit the directions of Eddy current, adding iron cores into the slots to increase the magnetic flux density (B = muH)
Could you use a belt instead of a chain to help with the weak points on the sprocket and the magnetic interference?
This was meant to go in the main comments. Whoops
Just be careful of road man holes lifting up to stick with the magnet matrix
*manhole covers
not possible
They are magnetic but it would slow you down if anything
@@Pooopersno shit!
Or the chain passing thru the magnetic fields developing a current and shocking you!
An interesting experiment - I was watching this with my son, who did an engineering foundation at uni before his computer science degree, and I predicted the heat problem. Well done - it didn't work as well as you'd thought but it's a good experiment.
If you revisit this project, you should try a halbach array for the magnets. Should get you a much stronger field
It will give you a stronger field but you also have to keep in mind that he didn't much space to mount the magnets. The magnets would touch or overlap with the chains and spokes if he would use the halbach config
@@Player-pj9kt he don't have to use chains there are belt driven bikes already and they make much more sense because the belt isn't magnetic
@fischX it still might get in the way. The spikes as well if he puts the magnets on both sides. Easiest solution is to use smaller cube magnets but those magnets are probably not as strong
wouldn’t it just give you a stronger field on one side? so instead of a bunch of change in flux from north to south from the individual magnets to a change in flux of let’s say north to nothing but with a bigger north?
would it actually be any better?
I was looking for this comment, I agree that a Halbach array should make even weaker magnets work better.
Babe wake up, new Tom Stanton video
“D-did he make a new air engine dear?”
@@diet-water No but it's just as pointless
@Don't Read My Profile Picture this is getting pretty old
Lol
"Speaking of nowhere..."
Halbach array would give you even more magnetic force per magnet given to the field direction you want. Of course you would simply heat your disc faster, so there's that. This is a super interesting concept though, for sure! You could also have direct magnetic interlock with a squirrel cage style ferro-magnetic core, like how induction motors work. I like the idea of creating a 0 friction gap in the drivetrain.
I wonder if he could get the copper hot enough that it stops being able to produce eddy currents. I know heat can kill a permanent magnet and hot iron won't stick to a magnet until it cools down.
@@andrewdescant Well, the heat would certainly affect the resistance of the copper, just as it does in any other electrical component.
@@andrewdescant I don't think you could reach those temperatures by pedaling outdoors, since the rate at which it loses heat increases with the difference in temperature vs the air. Would be wild though
Was thinking the same thing. Halbach arrays are often used in permanent magnet motors due to the lower weight and cost. It would be perfect for a project like this.
Wrap coils around the magnets and power them through an adjustable source to get variable torque coupling strength. If you put rotary encoders on the wheel and pedal crank you could implement a control system that always allowed a peak efficiency to be maintained for the pedal angular velocity. You could also implement kers on braking using the same equipment.
Great video, with brilliant visual comparisons.
A few options to make life easier: 1. Use a disk hub (machined mount ready to use. 2. For mag interference with chain...Use belt drive instead of chain... they are superior in some ways and used by touring cyclists.. 3. For spoke mag interferrence, "string" spokes are already succesfully used
In case you weren't aware, mag clutches do exist and are in wide use, up to around 20 horsepower I believe. Should be no issue for your uses.
I miss the air engine videos.
Don't those work by increasing the viscosity of the ferrofluid? No eddy currents involved.
I think magnetic clutches use magnets on both sides? So it'll be equal speed up to a certain torque. I doubt anyone would want to run something with constant slip.
@C. I think that's specifically when you want to lose energy, I.e., braking. You would want to use something like that for driving something.
I believe the air conditioning compressor also engages with a magnet clutch
This is cool. If you decide to revisit this idea, I suggest you use a one-way clutch bearing for freewheeling and also add a U shaped back-irons for the magnets. This helps steer the fields in a shorter path and should increase the flux (IIRC) in the gap on the copper disc while reducing the magnetic forces on the chain and forks. Soft iron is best however plain steel should be fine as the magnetic field in the magnets are 'static'.
thats good suggestion. It would increase the torque for that design but not the efficiency of the system right? The main losses are in the copper if I understand it correctly.
Actually, they now call it dynamo iron, as it is no pure iron anymore, but an iron silicon alloy.
@@LaggerSVK My experience with electro-magnetics is somewhat limited. My most recent experiment was a axial-flux motor for a heated stir plate I was making. I couldn't source suitable materials so I recycled the windings and core laminations from a large transformer to build it; not ideal for the frequencies that I drive it at but it ended up working reasonably well.
Just thinking about the problem with coasting: Would it be possible to make some sort of bearing or mechanical system so that the chain can 'lock in' and 'lock out' so that the magnets can still move with the wheel when the pedals are idling? Maybe a motor on the hub instead to counter-act the resistive difference? Kinda cheating though & probably way too complicated to be practical...
I was familiar with this phenomenon from roller coaster brakes, but you explored far deeper than I had ever seen before. Fascinating video and good explanations.
That was a brilliant, thoroughly well-thought and very well executed way to find out something is a not such a good idea. The effort put into this is admirable!
How about just a magnetic frictionless bearing...
Watched a number of your videos. So nice to see someone who truly understands engineering, can explain it well and actually make some impressive things. Keep up the good work!
if only he didnt have that bloody accent
So, if stopping pedalling means an applied braking-force, then that will be very inconvenient any time you've pedalled long and hard enoug,h and only need to use the bikes inertia (like downhill, or any circumstances where freewheeling is advantageous), then you're stuffed!
Definitely.
That was incredible, thanks a lot!
Two improvements are yelling to be done from a bike tech perspective:
1. just use a hub with a disc brake mount. It's exactly what you are looking for. (attaching a metal disc rigidly to a bike wheel)
2. use a bike with a chain shift as a basis: when you remove the cassette, you'll have a lot of clearance between the wheel and the frame
Also I'd bet that a FDM printed sprocket in flat orientation out of nylon will outperform any resin printed sprocket
To add to this, consider trying a halbach array for the magnets.
Also I know your intent was to get somewhat of a CVT effect, but continuing to use a gear cassette will allow for you to keep a more ideal slip angle with the copper.
I think his approach was perfect, because all the bike properties you mentioned would have made his prototype much more expensive.
Bro that's just POC. He's next Elon Musk in cycling, mass production of MagnetCycle(c) is already planned for next quarter! Keep tuned!
I actually think this project is really interesting. Unfortunately the transfer of torque will always be determined by the change in magnetic flux. Meaning that you will have to pedal faster to get it going and keep it going.
Or induce another magnetic flux which alternates faster as wheelspin. It is called electric synchron motor, and found in most current EV vehicles 😀
@@palohagara105Electric Vehicle vehicles?
@@tataduzy4260Yes, most current EV vehicles, with MOSFET transistors creating alternating current.
Highly effective and only 10-15 kWh/100 km = 10-100x less than combustion motor.
What is the problem? Calling BEV electromobiles "vehicle"?
@@palohagara105 It’s because EV means “Electric Vehicle” so saying “EV Vehicle” is saying “Electric Vehicle Vehicle”.
@@comeonandslamandwelcometot2418 ok I thought so, just "gramar nazi" problem.
It is normal when some category/abbrev became more common, it takes the semantic form of adjective/subject or even verb.
Like we have AC + DC, but if you are talking about current, you also say "Now we switch AC to DC current in a circiut" sometimes.
Or something like Congress resolution R268, abbrev used in many countries to add a certain level to complicated bunch-of-numbers and abbrevs, which are quite common in legislation.
Especially if it is generally-targeted text, which youtube viewers surely are.
And using frequent abbreviations adds confusion to text (for most not-profi readers). Therefore some, maybe dubious double info, adds comprehensibility, not reduces it.
Like: problem of Postal Codes or Social-Security numbers or other codes, which contain dubious but failsafe information, even when you do not understand or make error.
As you surely noticed on youtube or Twitter where many people use some "their best years military" abbrevs, or T9 auto-complete on mobiles = lots of uknknown shortened words.
So ok, and now whatabout fact, not form?
You have to admire Tom's enthusiasm, he had an idea and he set about trying to bring it to fruition. Not all experiments work , but I am sure this attempt has brought him some useful insights of what he might try next.
2:25 this is sweet but you need to account for the moment of inertia... by adding some extra weight on the disc for example. side note, on a bicycle you'll probably want the lighter material...
11:10 by intuition I would have attached the magnets to the wheel, not the pedals: you'd save on the zip ties ;-)
14:57 yeah obviously... it's like the arrow halving the distance to the target each time you look at it ; the clutch alone will never bring you to a complete halt
15:54 I was waiting for that one XD the 8kJ obviously don't account for the energy dissipated in the air. Please please please try again with the thermal camera mounted on the bike while riding! We want a graph!! I'd really like to know what happens to the torque transfer capacity (and heat losses) in relation to the temperature of the copper disc.
I pretty much knew where this was going, but this is brilliant : good preliminary testing, and I've been looking for a way to transfer torque without using hydraulics and this is just what I needed! Thanks!
Amazing idea! You can also separate copper segments into angles. This way the current must go in and out of radius. Your coupling will be much much greater! You can also drill lots of holes in the copper plate.
@notfiveo If you have electro magnets you're building a motor. More speed holes.
@@1800Supreme well steel is not as good as copper. And you'd need a battery for running the electromagnets. But the advantage is that you can switch them on and off to create some kind of a gear ratio I guess.
The magnets on the other side of the disk we cant see may be interfering or attenuating the magnetic field. I would test by first removing them leaving just one side full of magnets and the next test with different patterns, e.g. opposite sides, same plane. also using metal back-plates on the magnet helps allot
[S N] |Cu| [N S]
[N S] |Cu| [S N]
config 1/5
[N S] |Cu| [N S]
[S N] |Cu| [S N]
config 2/5
X X |Cu| [S N]
X X |Cu| [S N]
config 3/5
X X |Cu| [S N]\Fe\a
X X |Cu| [N S]\Fe\a
X X |Cu| [S N]/Fe/b
X X |Cu| [N S]/Fe/b
X X |Cu| [S N]\Fe\c
X X |Cu| [N S]\Fe\c
config 4/5
d\Fe\[N S] |Cu| [S N]\Fe\a
d\Fe\[N S] |Cu| [N S]\Fe\a
e\Fe\[N S] |Cu| [S N]/Fe/b
e\Fe\[N S] |Cu| [N S]/Fe/b
f\Fe\[N S] |Cu| [S N]\Fe\c
f\Fe\[N S] |Cu| [N S]\Fe\c
config 5/5
d\Fe\ or /Fe/a represents iron plates that connects two magnets together, one magnetic pole to another on the same side. a to a, b to b, c to c.....
X X represents the absence of magnets, Iron, or Copper. Nothing basically.
|Cu| represents the copper disk
[N S] or [S N] represent dipole magnets, N being North and S being South
You always have the most interesting bike technology builds. Your anti-lock brakes from a while back inspired me to design my own and I love the way they work
I would recommend not using a disc of copper, but an annulus. You could have "gearings" by having several nested annuli with notched / cutout bracing supporting them, and different gears would correspond to different magnet arrays for each radii associated with each annulus, where the field strength would differ for each array. But either way, this was a very cool (warm?) experiment!
Bloody smart Aleck, do it yourself and the go to the trouble to put it on u tube!
@@stephencummins7589 Thanks for your kind words! I was only spelling out an idea. Not diminishing what was done and obviously he put a lot of effort into this. I apologize for not having a RUclips channel and extra money to build projects to have a moral equity in commenting here. I know that everyone has the degrees of freedom in their life to do that and I'm sure you've gonna ahead and pointed out all of the other commenters' lack of platform content when they've made suggestions or had opinions. I will refrain from putting my musings and ill-considered ideas online in the future so as to not offend anyone's delicate sensibilities. Thank you for correcting me. I will say being facetious was not my intent, but I nonetheless deserve the insult for my failures.
@@pion137 The important thing here is that you learned a valuable lesson in RUclips etiquette.
Good luck with your sponsorships, future earnings and endeavors. 😆
@@whatsit2ya247 And yours!
I dont understand your idea but either way suggestions on most project based youtube channels are always welcome
Wish you would have reverse spun the crank to brake...or maybe ride it backwards 😊
Flip it (put your clutch on pedal side, not the wheel side) and use electro magents instead of permanent magnents. That way you can harvest energy while braking and increase your magnetism when you're applying power.
So it’s a normal motor at that point
Bro invented an e-bike
@@gibsonf06 mans proper smart, you get me.
I love how you had an idea and made it reality to test it. That's the sort of real-world findings that could prove to be useful for all kinds of applications that may even be totally unrelated to your project. I bet someone out there will see this and get inspired to try this in something else
But this is already in use. It's basically how an old school speedometer works. A spring loaded aluminium cup is driven by a magnet inside, that's it. Also many old record players use magnets to fine tune the speed (eddy current brake).
@@westelaudio943 Cool. I did not know that
Appreciate you Tom, the amount of time and effort put in to every video shows.
Would be cool if you could somehow harvest the energy and maybe even somehow reinject it into movement
HI Tom, first of all this video is great.
Secondly, I strongly suggest you to repeat the experiment trying to reduce the air gap. The first thing you shuld do is mounting the magnets with a plate of steel on the outside, the steel will increase the conductance of the magnetic flux increasing the flux in the copper plate (this steel plate would also act as a shield between the chain and the magnets).
Other improvement could be to mount the magnets between two copper plates, that would also increase the efficiency of the magnets, I estimate that doing that would give you the same torque with half of the magnets. The hard part is mounting the attachment.
On the mechanical side, it could be interesting adding a stage to the transmition in order to multiply the speed of the magnets.
yes, i see you know your flux.
Just a brainstorm. The reason for the heat is because of the electrical resistance of the copper disk. Also, keep in mind that electrons move on the surface of conductive metals. By thinning the copper disk and silver plating the copper (at least where the magnets are) we can reduce the heat.
@@TheAmity adding to your brainstorm, I'm not sure if skin effect takes place in this particular case. But if it is the case, making the disk with thinner layers of copper isolated between them would also improve the efficiency of the metal conduction. Because it would have more skins to induce current.
@@grannqnito I appreciate your kind reply. There are lots of factors involved in Tom's great project that are not easy to discuss/share in this way. For example: at the introduction of the video Tom showed us the moving magnet inside a copper tube (one the most efficient because of the circular shape of the tube). The current distribution inside copper dist is very chaotic/inefficient (in my opinion), but using a copper tube instead will be more efficient (in my opinion, again). I wish I could attach some images/sketches to explain my suggestion/theory about implementing it. I enjoy the exchange of ideas/thoughts in the frame of logic, it opens the mind to new doors.
I would also think that significant spinning mass could be saved by skeletonizing the copper plate.
Combining with your 2 plates idea, that could end up with less weight for near double the effect and spreading heat out.
That could in turn allow it to be smaller diameter and less magnets, further reducing spinning mass.
The shot at 7:41 showing the effect of different magnet amounts was amazing. I bet it lines up with it's plotted graph.
Seriously, that was brilliant
You could solve the magnets attracting to the chain and spokes using Mu Metal. In mechanical hard drives, they are thick and attach to the magnets, but completely prevent the magnetic field from progressing further, and help to contain the field in the gap where the voice coil moves the heads in and out of the platters.
Or use a beltdrive
@@G4ngsta4l1f3 Stole my thunder lmao
Use a disc brake hub, and flip the hub around so that the disk bolting section is on the Drive side. Then you can both on anything you want
belt drive is the answer
***Change the design slightly - put slots in the back magnet wheel so the magnets can move back and forth based on RPM maybe you would get some variability in torque base on how much centrifical force the wheel is applying the magnets since the RPM would would be larger when they are at the bottom of the slot and lower at the top of the slot.
A halbach array instead of a simple N-S magnet setup would would make the effect stronger for the same size/number of magnets. Besides, that, pretty cool!
That's correct but he will have to either have to cube magnets with the same field strength or he will have to increase the gap between the magnets chains and spoke for it to work
@@Player-pj9kt not really. A halbach array produces weaker field "outside", so the spokes and the chain should actually stick less!
@quinor I'm not talking about the sookes and chains attracting to the magnets I'm saying that the magnets he us using will physically collide with the chains
ehh clearances... fair point.
Audio glitching in the clip @12:11
Although you may not see this as a success, there's some great ideas here. You learned so much through it also. I think you will come up with practical solutions in the future. It's great that you have the mind and the tools to create what you envision. Great work.
Hello! I'm master mechanic with experience in 3D-Printing and CAD, so I watched this video enthusiastic. I'm really sad, the efficiency is so poor. But - if You don't test it, You didn't know it. I'm sure, You had fun to do it. Great work!
Cool concept! Great execution! To brake/stop better, you could pedal backwards to keep the speed difference up as you slow down.
That would have been interesting
That's clever. Nice . But it would produce an ever greater resistance on the rider
I really wanted to see this!
I'm so glad to see this channel doing well. It started out with such goofy ideas but Tom has kept at it and it and always comes back with interesting ideas and very good executions. Bravo mate
The sense of innovation in this video is rising by every minute. I love your work, sir
I know this is a bit old but at 5:25, you said you cant machine that thread but you have a CNC router. Why couldn't you thread mill it? Does your router not have true simultaneous 3 axis control to be able to do helical moves?
About 35 years ago, Schwinn Bicycle Co. had a frame you could mount your bike to that had your rear wheel run on a roller that was tied to an almost identical arrangement. You could vary the position of the magnets in the assembly by turning a knob.
Just thought I'd drop a line to say that I find this type of thing absolutely fascinating.. such great work and thoroughly entertaining! Keep it up my friend!
There's a reason this doesn't exist in a commercial product...
It's HIGHLY inefficient.
This reminds me a lot of a torque converter in a conventional automatic transmission for an automobile. You could take this one step further, as the auto manufacturers did, and have the option to lock the torque convert up so that there are no frictional losses between the copper disc and the magnetic drive.
While it was completely useless against a conventional direct chain drive, it was one heck of an experiment! Probably one of the the most interesting scientific/engineering experiments on RUclips! Love your videos!😄
Really like how you put the different tests with different variables are shown alongsude each other in real time. It really helps visualise the relationship between the variables, like a real life graph. 👏👏
Damn Tom, as a physicist I am excited about every new video you bring out. Your ideas have inspired me more than once to build fancy stuff.
Every time you have some different ideas, we see it implemented within seconds in the video. As an engineer, I know the pain anxiety of the challenge to go through implementing ,and the excitement during the test, and of course the joy when the idea works.
Testing out theory vs. real practical application. He makes excellent points. The next thing to do is to figure out a force needed to move the bicycle up to 20-25 mph to justify all of the benefits of the gear-less system. My guess is that some form of E-propulsion needs to be added to assist the cyclist in attaining the speed they need to enjoy the ride while at the same time adding in more resistance which would assist in the braking function. As he showed in the video, the braking system needs help too. With more force on the chain to back sprocket, more resistance is built up and maybe that would solve the braking issue. But in conclusion, I guess this is one of those "Good idea but not quite there yet," videos. Keep up the good work, Tom and we all are interested in seeing if you can get this design to be fully functional for the rest of us. Looks like a good concept for a bicycle company to use. Maybe hold off on showing your final "By God, it works!" version and patent your concept, instead and make some cash on this idea. THUMBSUP
Fantastic project! Thank you for going through the trouble of recording the entire development process and sharing it with the world!
@@matsuz100 patents only prove said person invented said thing. He can demonstrate that he came up with said idea here 1st icluding the dates of all the footage he has used.
But from watching all he has done I think with more work he is onto something great hopefully no toerag will steal his idea.
Finally he has inspired me, period
You're amazing to tackle and command this new concept! I wasn't surprised when the plastic wheel gear broke. There would be a lot of torque on that part to cause sheer. More MAG power and Innovation to you!
I don’t know if regenerative break is available for e bikes but this system can make it possible to recharge your e bike battery during down hill. It is quite interesting and love to see a design like this.
Regenerative breaking was built into my 2007 Bionx conversion kit. Newer models (e.g. Aventon) don't seem to have it. A pity.
@@Daroohabetter batteries make it less necessary for having a functional max distance.
Because a bike and rider is so much lighter than an electric car, there's really not that much energy to reclaim when decelerating.
The thermal issue and the images at 15:55 are good things to point out to the perpetual motion tinkerers.
When I've thought about doing something similar, I was going to mount the magnets to the rim of the rear wheel. My idea was to have a series of solenoids adjacent to the rim to act as drivers or breaks, with electricity from a pedal-powered generator, and a capacitor for a bit of breaking storage. It would be cool to see that in action, just in case you haven't done enough electric bike videos :p
Even dull looking copper is a great reflector of infrared light, like a mirror would do for visible light. It has a very low emissivity so you would have to stick some tape to it to measure its temperature with a thermal camera or you will just read the temperature of the things its reflecting. Interesting video. I was about to experiment with some magnetic coupling myself and was wondering about the alternating magnet orientation :)
Yeah he'd best get his camera checked it clearly didn't show the real heat source. Fake!
I kept a protective plastic film on the backside of the copper disc for that exact reason (notice the thermal camera shot is from the other side of the wheel vs regular camera shots). When aiming the camera at the exposed copper side, it just showed the temperature of the reflection.
Tom, your simply unmatched ability to logically apply principles of analytic geometry, test and evaluation, and the linking of the governing physics to mathematical expression is a masterclass that I wish I had in my undergraduate aerospace engineering degree program. I want you to know that your channel is more valuable than most engineering curriculum due to your ability to efficiently distill and demonstrate the power of iterative design for real-world applications; your content is the truest expression of what it means to be an engineer. Keep up the stellar content!
I love your bike-related videos! I'm currently trying to understand basic mtn bike geo, and am envisioning an experiment that I don't materials or experience to do myself:
Setup: Inverted pendulum on a car with adjustable axle placement, something to stabilize the pendulum (motor?), and a course with undulations to acceleration/decel and bumps to roll over.
Test objective: find the ideal axle placement that allows for the most stable pendulum, to the point minimal overall work is needed to correct/stabilize it over the course.
Expectations: widest wheelbase that can still clear the undulations, with the pendulum centered towards the rear, with maybe a 60:40 weight distro, on the rear may perform the best.
Lesson: be better informed, to help filter through bikes that may not be so good based on bike geo (ie. beach cruiser bikes, that have cranks in the middle between the axles, disguised as mtn bikes)
Regarding "gears" you could use some kind of centrifugal force mechanism, that pushes counterweights out when you pedal faster, pulling the magnets in. Having the magnets closer to the rim will give you some leverage allowing for a lower "gear" when pedaling more slowly.
This might be difficult to build and also difficult to control when riding, but on paper it should work
a variomatic from DAF. No magnets required.
@@andreasrademacher5715
Simply a modern scooter or snowmobile transmission 👍
Nice video! I think you can brake faster if you pedal backwards. The higher difference in RPM will make you brake faster, even at low speed.
The forward force on the pedals is really strong, so I was only just able to lock the pedals. It's not like pedalling backwards on a freewheel.
@@TomStantonEngineering first of all: nice work! To give you a hint about the behavior of your system, it is the principle of an asynchronous machine with a so called squirrel cage. That's, I guess you already know it, the most popular electric motor you find in industrial applications. The amount of torque depends on the slip, means the relative difference in speed between the wheel-disc an the magnets. Theres a formula called "kloss equation". You will find curves that show you a maximum of torque depending on the so called slip. If you're more interested, we can dive deeper, since I worked at an institute for electric machines. Regards, Robin
@@TomStantonEngineering - some electric machines can CHANGE their coupling level - because they have electric magnets instead of permanent magnets.
this means if you power the magnets down, you will get a real free wheel. also the slip can bei tuned to your needs. - have fun!
in effect its the induction brake - but modified.
@@TomStantonEngineering thanx for clearing t5hat up I was thinking that throughout the video whole thing was truely inspiring you have a new sub! whats next? an improvement or moving on cant wait for either?
13:19 Have you also tested freewheel and flywheel and thicker copper disc? And on the backside of magnets you need normally steelplates, to better feed the flux, and you will not have problems with magnetizing of chain.
Great video Tom! Love the in depth testing you did. Although I really wanted you to spin the wheel in the other direction to try and stop the bike quicker. I assume spinning it faster in the other direction would act as a better brake than just the magnetic friction.
GOLD
I think you have one of the best engineering explanation videos on the internet. You always come up with some great crazy idea and introduce and explain bunch of ideas along the way. I'm super excited every time you upload!