The Prototype is Finished - DAY 10 - Marble Machine Flywheel Prototype
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- Опубликовано: 18 май 2024
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Thanks to Yan and Tom for fantastic work on the Tightinator Software:
github.com/YanFett/Wintergata...
tom.mcnulty.in
The creators of the software describes it as
"A Website that takes a wav file and outputs a csv file of all peak timings and supports that data with graphs. Its goal is to save time and help in the pursuit of an ever tighter marble machine."
Thank you for helping out with the Marble Machine process.
The prototype is designed to answer the age old question: Can I play tight music using a very strong flywheel? The new flywheel have 20x more moment of inertia compared to the MMX Flywheel.
We are recording at the wonderful location of Siegfrieds Mechanical Music Museum in Rudesheim Am Rhein, Germany. Check out their youtube channel: / @musikkabinett
Edited By the Glorious Hannes Knutsson From the @Trainerds RUclips Channel
Trainerds: / @trainerds
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Wow! That has to be the best flute ever made by human hand! The impeccable playing technique too! That kid has to be a genious to be able to make such a beatifully superiour instrument! (I am definitely not him)
That three-limb technique is certainly unique. Makes me want to see a really big one with foot pedals!
Honestly I was first expecting it will drop marbles somehow. :D
You might enjoy Nicolas Bras and his wild instruments :) nice job on the flute!
@@NoxiousPluK He was actually one of my inspirations for making it!
@@alvelycken7893 Awesome, happy to hear that! Keep it up! :D
It seems to me that Martin is testing two different but related things: 1. The machine's ability to keep tempo. 2. Martin's ability to drive the machine.
true. i don't know why he is trying to achieve a consistent bpm manually. he should again use a motor to drive the flywheel and check the "tightness" that way.
The best way to characterize the machine alone is to bring it up to speed and then stop adding power. Just let it wind down. That behavior will be consistent, and any deviation from that when martin is driving it is entirely due to Martin.
Furthermore he needs to put the results of different speeds in relation to the speed. The tightness deviation at double speed is equally off at half the time. So 3ms at 60bpm = 1,5ms at 120bpm
What is the baseline for manual adherence to a click? Martin should just record himself playing a very basic beat on the drums and record how tight that is.
Pedal to drive the weights up. Weights to drive the marble machine with a gear selector for the bpm. Crank will be needed to spin up the machine before you engage the weights.
I can’t believe it. We finally got to hear the MMX play a song.
It did play a song in the last videos
Sort of. It is stunning, tho.
10 years of mincing around
If using a single of its instrument at once is enough to classify as "playing a song" then we've already heard it play songs plenty of times during the build series
That angle grinder has made him plenty cash with zero product delivered
If you want to go with the crank, a freewheel mechanism like on bicycles would be nice. That way it won't smack you when you stop cranking.
Edit: Actually, you could also use a bicycle derailleur to have gears. That way you could get up to 140bpm or maybe more.
Came here to say literally this. You loose so much energy with the system pushing your weight up when you’re trying to find that bpm
Yes using the whole drive train from a bike could be a winning concept. I mean there are spare parts everywhere and it works.
Agreed, I think the problem is that while the pedal system can have more Power placed into it, it is also less direct. Which is probably why the crank feels better. However, similarly to a bicycle, you can only really push down from the top of the wheel, so you are only able to add less than 50% of the potential movement into the system, whereas a hand crank you can pull up and push down, resulting in a better feel. Perhaps there is a way to combine the two methods, one for speeding up rapidly, one for control?
The only downside with gearing is that the cranking motion wouldn't line up on beat anymore which is probably part of what helps keep the machine on beat.
@@unicyclewsu yeah that's true.. and a hard problem to solve.
Keep in mind around 5:09 and 7:38 your body mechanics are going to take a toll if you are not cautious enough. You should be able to switch positions and switch appendages, or else your likelihood to sustain injury due to repetitive motion will increase drastically.
A good measurement for judging the friction in the system is the time it takes for the rpm to drop to half the initial speed. When you let it wind down to a stop you get a combination of the effect of running friction and static friction. The 50% time point is only affected by the running friction. That would be a good baseline data point.
And because there's no more fluctuating amount of energy being put into the system at that point, the result should also be consistent! :D
I love seeing Wilson spin as the progress indicator.
Pretty genius
You’re fixing one of the few things that worked so reliably on the MMX, the power source.
@wintergatan I used to play in marching band and with slow tempos it was always important to subdivide the beat to stay in time better. Maybe two contact mics would help so you get the feedback twice every beat instead of once every beat.
@Wintergatan you could control the output power from the flywheel, with a torque limiter + governor. Then you could be at an exact BPM as long as the flywheel is above a minimum speed (thus you do not need to keep the flywheel at an exact speed)⚙🧑🔧⚙
Yes! He should investigate this. And also an electric drive incase he instead want to focus on playing instruments.
When you mount the fly wheel on the chuck, put your gauge on the rear face to measure the run out and get it level in the chuck. When you machine the front face it will take off the wobble and both faces will be parallel 🙂
I'm not a machinist, but I was thinking the same thing when he said "I can get 3 sides perfect"
The issue there is the already cut center hole for the shaft, which was also finished on a loose chuck.
@@randommcranderson5155 If the shop has a live centre and a lathe dog, he could mount the flywheel with the taper lock bushing onto a short centre-drilled shaft and machine the flywheel relative to the shaft instead of the hole. This would allow the faces and outer edge of the flywheel to be turned relative to the axis of the inner diameter without further machining it. This would also allow the flywheel to be turned around without losing the face plane, so it wouldn't need to be indicated back in when turning the other face.
I've only got high school machining experience so I don't know if this is a faux pas in the machining world.
@@randommcranderson5155before machining the middle hole he still should measure the run out from the rear
Wouldn’t it be better if all three discs were lathed?
Regardless of pedal or crank. I’m thinking the limitation will ultimately be Martins physical endurance. He’s either gonna need to bulk up or employ a motor driven power unit to get through a concert.
Exactly. Powering it manually for long enough to play a full concert live would be an insane workout. It is quite obvious he's going to end up with an electric motor as he did in MMX, but - for some enigmatic reasons - this time after spending a lot of effort attempting to build a mechanical storage of energy and its distribution system.
He can solve this problem with the chain drive
I suppose the Marble Machine wouldn't play every song of a concert.
@@michalgrbkThe ultimate solution would be to have audience members take turns cranking/pedaling the machine. Martin gets to rest, and a few lucky fans can feel like they're part of the show!
@RandStuffOfficial That's right probably, however even during tightness tests, Martin was already on his limit and Hannes helped out to pedal. This asks questions.
Footpedal + Governor would be an ideal combo - cuts down on fatigue while maintaining the tempo you need.
Keep in mind that once you start lifting hundreds of marbles per minute (and various additional mechanical losses), your input power needs will go up... a lot
This is my concern as well! Pushing on the foot pedal already looks difficult. Powering the entire machine will be exhausting! Getting it from zero to speed is going to be a challenge.
Don't burn yourself out Martin !
Courage !
Eye like your profile pic.
Now all you need is to create a governor to keep the speed at the same rotation you wanted. It will help level out the rotation and keep it where you want it, even when pushing the pedal to go faster, with out peaking up past your rotation.
Edit; you may want to add a rotation gauge so you can see how many revolution per minute you are going.
You could maybe add some kind of centrifugal governor to the system to keep a constant speed, similar to steam or sterling engines. It could be made adjustable to hit fixed increments of RPM
It's in the plans
After investing this amount of time and numerous efforts, i'm curious why he is avoiding making something like this.
If this is a critical feature to have high bpm tight, this is an obvious measure to implement, i guess. Ability to add some energy to the system without additional task to be precise in bpm should make this doable.
@@darkiee69 if it is in the plan then why he is ready to give up if this fails without that?
The pedal's flex might be part of what's making it feel less tight.
Adding a half to 3/4 length supporting triangle gusset centered under the attachment point would fix the flex. I think the link is too close to the center, making the pedal input very heavy and insensitive. but it kept the pedal travel reasonable, I guess.
I believe the reason you are seeing this mismatch is the method of measurement. The standard deviation is just measuring how consistent the tempo is but as you can see the data is oscillating, likely around your desired tempo. This is because you need to match your metronome tick to the machine tick so you have to speed up and slow down to align yourself. If instead you were just trying to maintain a constant temp with a screen which told you "50 bpm" or one of those devices that can tell you "50 rpm" which they use for measuring high speed rotation and tried to match that instead I believe you would get results more consistent with your feeling. Its possible the hand crank maintained a tempo more close to the tick but oscillated more. This is just my best guess.
Agreed 100% - with the crank, he was both accelerating and braking, so it stayed closer to the target but had more overall change.
With the pedal he was only accelerating and coasting, so there was less deviation.
A BPM meter could be the right answer if this machine is to be the metronome for everything else on stage.
I'm trying to understand the issue you are seeing with the standard deviations vs your qualitative expectations.
It sounded from the clips you provided that the hand-crank was more aligned to the click, while the pedal was consistent, but not aligned. From what you showed of the software, it's detecting peaks and then quantifying the time between them to get the BPM.
I have a couple of thoughts from the limited observations I can make from this:
1) It looks like the software is reporting the standard deviation from the mean *of the data* rather than from the *intended* mean. E.g. your 80BPM test is looking for a mean of exactly 500ms, but your standard deviation is reporting relative to the measured mean of 500.44. You might get a better insight by using your target interval as the expected value in your calculation, and not the mean.
2) The crank might be giving you more control, meaning you are inserting more acceleration and pauses to match the click - this is a lot better for you as a musician, but might be less consistent in the data.
In other words, the pedal might be more consistently wrong!
I was thinking the same thing but you explained it perfectly.
I believe more consistency means tighter music right? So more consistently wrong is actually better?
As a musician, having a lot of control is actually very important tho. So idk honestly..
The community that's born around your work is amazing
When you single handedly inspire a whole generation to build Marble Machines.
I think the crank seems tighter because you're able to visualise when the arm is about to hit the mic. If you had the same visualisation for the pedal you might find it "tighter" as well. The issue will be the "beats" inbetween.
Martin: I need to develop a scientific method to test this hypothesis.
Also Martin: I ignore the science, hand crank is more comfortable.
Every time a new Wintergatan video comes up, I can’t stop thinking about how big your music and shows will be. I keep telling my friends you guys are the next big thing. Amazing progress, especially since the very first marble machine. Do not stop and I only wish you the best of luck continuing. No matter how long it takes I’m here for it!
Lol, you're kidding. Martin hasn't played a show in years. Is his band even together? Talk about putting the cart before the horse.
I don't even care about his band. I just love him as a person and enjoy his videos.
@@craftylemon2460 Have you ever met him?
I think the feeling that the pedal is sapping power is because it sucks in energy as it rises but gives it back as it falls. This evens out across a beat but could be affecting your rythym mid beat.
You may need a counterweight to prevent variation in timing across each beat.
The pedal doesn't take energy while the machine is turning on itself, but it steal energy from your feet when you are powering the machine (the energy is lost mostly in the bending of the pedal I think, so as long as you're not powering the machine, the pedal doesn't bend).
The pedal arm is a spring. What you put into it at the top of the stroke, it gives back at the bottom when it straightens again. So long as your foot is still pressing down while the spring returns to neutral, that energy will go into the drivetrain. There will be a little loss to heat, but it's not like Martin is permanently deforming the steel.
@@ps.2 I can't agree with you more. The only losses the pedal introduces are that of friction on the bearings and the heat from deformation, both of which are of no concern. I'd love to see the pedal structure triangulated so it stops bending so much, but that's just because I'm worried it might fail from fatigue after hundreds or thousands of hours of use, not because it's eating up any worthwhile amount of energy.
you could use gears to achieve higher speeds. maybe a CVT (Continuously variable transmission)
@Wintergatan Hey Martin, it looks like your handle came lose in your hand cracks. If you look at the earlier part of the video the hand crank and the plastic contact arm are nearly but not quite parallel (really bothered my OCD) but then at some point the crank arm was no longer in sync. There is a chance some of your driving force was lost in the crank. Also, the wedge to raise the legs of the machine also may have absorbed some of the downward force of the cranking. Lastly, you will certainly have more leverage force with the step pedal because of the length of the lever, if your hand crank was a longer lever it would have comparable values, but then your arm would need to go in large circles, so you would be better changing it from a hand crank to a hand pedal similar to that of the foot pedal, but I'm sure an up&down motion with your hand would be very exhausting. Another thing to consider is the strength of legs versus arms. A person who can only benchpress 110 U.S. pounds can probably properly squat 300 U.S. pounds easily. We have way more force with our legs than we do our arms. So by nature, it might play tighter with legs. You should have Hannes do the hand crank test, that would be a good controlled variable to see if athletic fitness has any factor in this machine or not. Not saying you aren't fit, but you do not have Arnold Schwarzenegger ripped arms so this crank method might not be for you. This also takes the bias of the test our, because you are the common factor here, and if Hannes gets the same results then we will know it is the machine. Just a thought. Thank you for keeping this dream alive!
From a physics standpoint, the larger input will cause a bigger change in the system. In other words, the foot pedal should be much less tight than the hand crank because the power input pulses with the foot pedal are much larger, or at least much peakier, than with the hand crank.
Also, as long as you don't leave the ground, any force you apply with your foot has to be less than your weight. A force greater than your weight would result in a jump off the ground. In order to apply a force greater than your weight you would have to hold onto something or be strapped down or be holding some weight.
Hey Martin. One thing that you can change on the prototype that isn’t that hard is to make a lattice (fackverk) construction to the peddle. That way you get it stiffer whit out a lot of extra weight. It should make the feel and input feel more controlled. Best regards Jimmi. 😊
That flute idea was sick! It does seem like it would be easier to play sitting down, lol
I don't about new marble machine, but MMX is just stunningly beautiful I felt really sad when Martin announced he wouldn't continue working on it, but seeing someone take on it where Martin left feel amazing, maybe it would never be good enough for a concert but at least itu would play a song one day
Looks like you've had a productive, if tiring, week. Thanks for sharing it with us.
14:03 Carlos could you please keep it down with the candy??? @AnjudaGuitars
you need to put a sprag on the handle. This makes the handle safe and useful.
The belt is stealig a lot! Try the same without belt
You are trying to match Phase AND beat… your testing methodology is bad, you should only match beat, not phase. Ask your programmers if they can modify the software for ‚live‘ input and output your actual live bpm, and then play an exact 80. you can see the wavy bpm when you over-correct constantly the phase instead of bpm in the graph!
Given that you’re right handed, why not turn the hand crank in the opposite direction, then your other hand wouldn’t be in the way of the rotating handle
If you want to build clockwork, you should study clocks. If your foot pedal or crank wound a spring, the spring could apply steady pressure to an escapement. You would get incredibly tight music.
I look forward to this everyday!
About your focus on tight music: I think you would find it impossible to find a single power plant on Earth that perfectly maintains their output frequency (50/60 Hz). They are capable of compensating for frequency drift over time. This is important because so many devices depend on that input frequency.
He doesn't have an objective metric to compare tightness, so it's a moot point. It's not tight compared to a power plant, tight compared to some other musician, or even tight compared with the movement of planets. It's tight compared to which side of the bed Martin woke up on that day.
Totally agree. Has the definition of tight vs untight even been defined? A few ms variance will sound tight to most listeners I’m sure
One of the best and most moving things about music is that it *can* change tempo, sometimes gently, sometimes abruptly. Yes, all the instruments need to play at the same time, but that's not the same thing as saying the tempo must never change. I suspect your intuition about hand crank vs pedal is that for the pedal, changes are slower and more incremental, i.e. the gradient of tempo change is lower. With the hand crank, I bet you're able to adjust more quickly to being ahead or behind, but those rapid changes may not be what you actually want.
Is there a way to set a limiter? Like, a lever that sets maximum bpm to 80 or 120 or such, and any excess momentum goes into spinning a wheel not connected to the operation of the machine?
It could be done with with some form of an electronically controlled clutch, or even just an electric motor. Have an arduino control the setup to bleed energy to an extra flywheel or charge a battery via the motor (regenerative braking, basically), then feed that energy back in the system if the bpm starts to drop.
It's a bit of a complicated setup though, and arguably not as cool as a fully mechanical machine.
Can you draw power from a system without changing it's speed? The point of direct drive was to keep the pedal/crank synced with the beat, but if the input is allowed to send power past the output shaft, won't that necessarily desync them?
I love that you're back. These videos are great. Keep it up. Your video are easily my favorite things on the Internet.
I still have my bets on the Huygen drive, I'd love to see a prototype with that
You've built a community, Martin, and now it's coming home to roost, so to speak. Nice.
Such a cool community around you Martin. So awsome!
THE BENT SHAFT is likely the veriable between the foot and hand...
the wobble when using foot - you can see it wobble more - then when you are holding the crank.
Congratulations! I've been living this small journey along the way. Can't wait to see what's next
*loving
This would (probably) require a different data gathering mechanism, but one possible way to get a real-time measurement of the speed of the shaft would be to attach a small DC motor. The voltage generated by the motor would correlate to the speed of the shaft, and fluctuation in the voltage would show the increase/decrease in tempo. This would have the side effect of placing a slightly load on the shaft, which could make for a slightly more realistic measurement than the unloaded flywheel does.
the most important thing you are doing is enjoying the process, no matter the result nothing can take that joy away.
Using the crank allows you to match the metronome more precisely, which makes it feel like you're playing very tight. However, as you're constantly adjusting to the metronome, the time between beats will actually vary a bit more, meaning it is less tight. Using the pedal makes it more difficult to adjust the tempo to the metronome. But the variation in time between beats is smaller, which equals tighter music.
That's so cool to see so much progress and so much will!!
I agree with the need for a governor. But I would also suggest a slipper clutch on the flywheel.
This would isolate the pedal and first wheel. With the advantage of being able to add a spring to keep the pedal in the raised or lifted state. Thus allowing you to start the movement with just the pedal.
As for the connecting arm from the pedal to the first wheel, I would suggest a turnbuckle with locking nuts. This will give you adjustable linkage that can be set with two wrenches. And would not require disassembly of the unit.
These are just some thoughts I had. Maybe they help. Maybe not.
Either way, please keep up the good work. Thank you for the awesome vids.
I think you need more resolution on your timing wheel to see the fluctuations induced by the pedal
next step: make one that incorporates the Hyugens chain drive, and get even tighter music
THIS. Use a governor (I'm fond of the kind on steam engines) to set the tempo and your input patterns won't be a factor any more.
It have been lovely to follow your for this 10 days! Keep up the good work! Looking forward for the next step! 🎉😂
Jan and Tom are absolute legends for pulling that software together so quick! Also to Sebastiaan for getting the computer set-up! Well done guys! 👏
Love this!
Here's a general machining rule of thumb.🙂👍
Always utilize a machined surface whenever possible.
For example, with round 2 of the flywheel, you should face one side, flip it on the chuck so that the now flat face is sitting against the, also flat, jaws.
As opposed to a rough and wobbly face.
Normally, this wouldn't be necessary on a lathe if the stock was clamped on the OD by the chuck. But in this case, there is no extra stock to hold that way.
Heck, you may even want to look into having the tops of the jaws milled or surface ground to improve their flatness as well.
Hope this helps. Great work so far and good fortunes upon you, your team, and your band. 😄
Yeah, rough cut your pieces, affix them together, mill one side flat and and also mill your inside diameter for the bearing, then you can face the outside edge and opposite side on the lathe.
You should add a governor to the current prototype before calling it on that one. Also none of us would complain if you are not manually cranking it. If you had an electric cranking and just played the instrument we would all be happy. We just want to see your creativity and music on display.
Yes! Would rather have him running around, changing the instruments than manually turning the machine. Of couse there could be an manual option, but I rather see people running around and really shifting, moving and doing different things to produce the music they want.
MMMM idk. When the 3rd iteration started, I and many others specifically complained about this exact thing. If he is not manually inputting into the machine, and he is striving for 0ms standard deviation and all these things, at that point it is not an instrument, it is a computer. I think absolute perfection is worse than minor flaws
In the end, this whole project is just the relevation for Martin that he wants to be an engineer instead of a musician ;-P. All jokes aside, Martin, I really liked the song you've used in the video "marble conveyor complete", if possible, could you ask the rebuild team if they would be able to re-create the song on the MMX (live). Would be epic! Love the project and the new positive energy you radiate in your series! Cheers.
Thank you
I think you need stomp pedal that restarts the click. You are trying to do two things at once which are tied together so you're fighting yourself. You are trying to get the machine to the right speed (frequency) but you are also trying to get the piezo synced with the click (phase). The problem is, if you get up to the right frequency but you're out of phase, the only method you have currently for changing phase is to speed up or slow down, i.e. losing the frequency. You need a system to electronically shift the phase, which could be as simple as an electronic switch pedal that sends a signal to restart the click at that instant. Then all you have to do is stomp when the piezo is just about to hit
I love Your work and energy from that all people. 😊
love your channel
"People have suggested a software" - Pft, I wrote one last year, which I have said also on the Discord with people promising to tell Martin about it.
But yeah, no drag and drop, that's for sure. I don't even have a mac. 😀
Awesome as always - thanks for sharing this! Also, two things I would like to see tested are: 1) A shaft key for the hand crank, so it's always the same angle as the contact mic and could be used to "feel" the position of the beat, and 2) A bi-colour LED that glows red (to slow down) if the contact mic triggers before a preset BPM, and green (to speed up) if the contact mic is behind BPM. Also, the LED brightness depends on timing difference.
Nice job Alve!
Also thanks to the other Marble Machine builders and data analysts and welders and machinists.
Congrats to the kid that knocked-out is own working marble machine!
I feel like having an assist motor to add some power but not fully drive thee system would help by requiring less large muscle group movement to drive the system. It would allow hand cranking also.
you need a gearing system like a bicycle so you can keep up. In fact you might be able to add a bicycle gear system so you can crank less and get more speed.
also add a clutch so that you can disconect the machine from the power drive and reconect without the spin up/down time
Let's go Yan! He does what he must because he can.
For the good of all of us, except the ones who are dead...
What about using a belt-driven conical pulley with a spring-tension adjustment for RPM? Something similar to what go-karts use? This would allow you to continue to use the pedal at whatever natural rhythm feels right, and any extra torque would be absorbed by the clutch. You could probably even use a Bowden cable and lever to adjust the spring tension, giving you a BPM Lever!
*The angles ranged by the new foot pedal don't match extensions of your leg in an ideal way. You need to control all of the thrust phase, maybe resist the return a little too - this may help.
Interchangeable gear ratio, so you can tap half, double or triple time at a more comfortable pace.
What if you followed the lead of some sequencer-programmer types, who actively introduce imperfections to avoid sterility and emulate a human feel, and viewed the machine as producing it's own groove to which you can, in turn, respond. There's tight, but you might fall into feel, by reaching for perfection.
Martin, when you have the rest of the machine built there will be a lot more resistance slowing down the flywheel, right? With the pedal, you only are able to accelerate the flywheel, not decelerate it. With more resistance on the system, it will slow down more quickly when you stop powering it. If I'm not missing something, this should change the results by a lot, because the system's response time will be reduced. You'll have to modulate your input force more quickly, but also if you exceed the desired speed you will quickly return to it.
I think what makes a crank handle feel nicer is that the beat always happens when the handle is in the same position, so it feels tighter and makes it easier to get in time with the metronome.
The treadle pedal still has a fair bit of flex, so the beat doesn't always hit at the bottom of a step, so it feels a lot more floaty and inconsistent when playing, also making it a lot harder to synchronise. A stiffer pedal lever arm, such as a truss structure rather than a single box section, would help synchronise the steps to the beat.
First: Energy is oscillating towards and back from the pedal when it goes up and down. So the angular speed is also varying with each half turn but the mean value stays the same.
Second: You could use a light barrier or an proximity sensor to get a perfect signal for each rotation.
When you crank, the pickup is directly connected, so you sense the beat at the top of the turn. On the pedal, the beat is not at the bottom of the pedal push, and isn't synced directly.
Nice
GO MAN GO!
link the Huygen chain drive to the flywheel and pedal, it solves all your problems in one go.. if you need grip for the drive then lining the pulleys with soft plastic or plasti-dip could work paired with a steel wire, if i remember how that mechanism worked right.. all that is for certain is that the problems you are finding would be gone (at this step).. lets face it, there are gonna be more moles to whack.
I'm not an engineer, but a spring loaded pedal with a catch and a "sawblade" gear would possibly be a solution for the pedal. It only engages on the down stroke and the return has it's own power - as long as your foot doesn't slip...
WINTERGATAN is part of our Global Zeitgeist … just with Marbles.
Congratulations 🍾 on this continuing success.
Godspeed
Reminder: PERFECTION IS THE ENEMY OF COMPLETION. ASK *NOT* "IS THE MUSIC AS TIGHT AS IT CAN GET?" -- ASK "IS THE MUSIC TIGHT *ENOUGH* TO BE ENJOYED BY THE AUDIENCE AS ART?". I shouldn't have to tell YOU that art is found in imperfection as much as perfection!
I think something that might have been missed out in the data analysis is how quickly the tempo changes around the desired bpm. Martin felt that the hand crank was better, but the numbers he was looking at didn't show this. It's possible that with the foot pedal, the bpm drifts and oscillates either side around the target bpm rather quickly (so it might be a bit fast for a couple of revolutions, and then slow down and be a bit slow for a couple, before speeding up again...), but with the hand crank, Martin was able to approach the bpm more slowly, making smaller adjustments to bpm over time, so it would take more revolutions to speed up or slow down. You could think of this as the frequency or period of the oscillations in bpm either side of the target.
You *MUST* test the gravity style. It will be SO much easier to play tight music when all you need is to "swap out weights" for specific BPM speeds.
What Martin needs is to send his input through a governor. Let machines handle the work of being precise.
You should take the timing measurements off of the flywheel shaft. When using the hand crank you are applying torque at the measurement point. Torsion on the hand-crank shaft will cause the shaft to twist thereby affecting the timing measurement. The flywheel shaft should do a good job of isolating those torque pulses.
Looks like a lot of fun different people :)
Holy crap dude, you don't need any more accuracy. From my experience quantizing drum tracks, the absolute best "in the pocket" drummers are +/- 10ms deviation on 1/4 notes. Very impressive what you and the community are doing! People are amazing when given the opportunity!
good on you for testing your theory about the pedal sapping energy. textbook example of design process.
The pedal and the crank won't take much energy out of the system over a longer period of time; but on a short timespan they will take energy out and then put it back in. If you counter balanced the crank, it would be better still. Similarly when you're looking at the flywheel. Yes, it's good to look at the side to side wobble, but what seems more important is looking at the rotational speed consistency. When you were looking at the side-to-side wobble, you could also visually see the slow down and speed up in there.
When you were measuring the high and low point, it would've been good to measure whether just the bar itself- right next to the fly wheel, if that was centered. It will be in the lathe but it would've been good to test if the same is true on the prototype.
this manual system seems like it would be adding to the difficulty and saftey issues. I'd imagine nearly impossible to keep tight but varied timing with just a manual drive and flyweel energy storage. the electric drive of the mmx seemed to go well
Love your videos Martin! Congratulations on your new project milestone!
I was thinking would it work to have a second flywheel that would be an intermediary wheel between your larger wheel and your energy input (hand crank or foot pedal). You could then introduce a little gearing between flywheels. This will keep your main fly wheel at a steady 80bpm while the first fly wheel takes your sporadic energy inputs and normalizes that to a steady 80bpm through some sort of gearing mechanism to the second flywheel.
It is very easy to vary the crank speed while a pedal action tends to be more constant due to larger muscles and mass working in the leg. So the pedal will have less deviation from standard than the hand turned crank. For more accurate timing, a speed controller similar to the old mechanical 78rpm record players will be needed.
You should de-couple the rotational speed of the crank (whether it's a pedal or a handle) from the speed of the flywheel. The crank should only add energy to the system, and it shouldn't even add speed to the flywheel. There are ways to do this, including fee-hubs from bicycles (some of which are totally quiet). Furthermore it's commendable that you should want the machine to be human-powered but I'd actually make this human power produced by a stationary bicycle. You could have people from the audience take turn pedalling, and it would strengthen the level of fun and engagement of the crowd. People who pedal would literally "feel" like the concert is set in motion by their action. A unique sentiment that only a musician normally encounters. Furthermore, the speed of the flywheel should be unrelated to the BPM of the music ; you should de-couple there too, and use gears to change the generated pulse. All of this requires a very substantial flywheel that spins very quickly. It's doable. The advantage of decoupling the flywheel is that your music tempo will be very steady, for a long time. I would argue also that you could drive the flywheel by an electric motor that is itself powered by a human on a bicycle dynamo.
What about an assembly that allows you to put in additional rotational energy into the flywheel but with a governor gear assembly that limits it to a set tempo? That way you could put in more energy than necessary but have it limit to the tempo you desire; you’d just need to keep the rotational inertia at or above the required amount. Then you’d just need to validate that the governor gear assembly played the tight tempo given adequate input energy.
You could consider adding inertial counter weights to the first pulley to stabilize the input speed into the flywheel. Although it would need to be very sensible to work properly. Or get the fly wheel a lot heavier.
To me, it make sens the pedal is more precise as the movement amplitude of your foot is a lot smaller than your hand on the crank.
yes, but it is good to see you working
To improve the consistency of the bpm, it might be beneficial to look at the rotation like a driven harmonic oscillation. Because you keep moving around the wanted frequency, it seems like your system is underdamped. The best way to improve this would seem to be some sort of velocity-dependent brake/resistor. Maybe something like an eddy current dampener or a liquid dampener might improve the frequency. You could even go as far as to calculate the required damping if you know the angular velocity and the moment of inertia of the flywheel. In case you want to know more about this, the wikipedia page for harmonic oscillators is quite informative.
I think the reason the pedal doesn't drain energy from the system is that it gains some potential energy every time it's lifted up by the flywheel, and gives it back when it falls down again. Theoretically this should result in a slight fluctuation in speed once every revolution, but it's probably too small to notice. If it were a problem, adding a counterweight to the pedal might help.
Maybe you are feeling the crank is better, due to an operation bias, that is making you prefer it? Could be a matter of practice with pumping the peddle with your foot, vs. cranking with your hand. Pending what you are used to, one of those things will feel easier. Also if you are hand cranking it, will you still have the freedom to operate the rest of the machine? Can you make the music with one hand cranking, while the other hand is doing everything else? Or will it be better with the foot doing the power, while you have two hands to make the music?
A flywheel does not do speed regulation, it simply stores energy and then release/returns it. Every time you push on the pedal you are affecting the output speed, and when you don't push on the pedal, friction is slowing down the flywheel and changing the output speed. You need some form of speed regulator (governor) to allow the flywheel to produce consistent rpm (rotations per minute) output. This speed regulator will then decouple your power input from the flywheel output. That way the governor will take output from the flywheel (energy storage) and produce a consistent regulated output, while at the same time you can add power/energy to the system via pedal or crank without influencing the output speed. Without a governor you are relaying on your human ability to regulate the speed/rpm, which as you have started discovering is very difficult to do. Remember, you add energy to a flywheel but once you stop adding the rpm output will slowly decrease over time due to friction, it will never produce a consistent speed output. And you human pedaled input will always be adding spikes in speed, as you add energy to the flywheel.
11:36 there are so many variations and possible combinations of parts fort this, it is hard to know what will fork for what. That is the whole problem with this journey. Martin is really pawing the way as he goes. It is a hard path but I believe the reward will be amazing once he achieves his goals.
you should consider re 'turning' the plates while the shaft is installed.... that ensures the outside of the plates are concentric with your shaft.... May help with some of the vibration.