3D Printed Stackable BRUSHLESS Motor Gearbox
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- Опубликовано: 7 фев 2025
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Thank you for watching the video! Links to the CAD for this project are below as well as links to the hardware needed to assemble it.
CAD Files:
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Small addendum to the video. The final torque value I gave was correct but the values shown on screen were wrong. The load cell was measuring weight so the maximum weight seen was about 9500g not newtons. Sorry about that.
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Don't use white lithium grease on plastic parts it will eat away at the plastic parts over periods of time rather use a silicone base grease or grease that safe on plastic.
UPGRADE TO CURA 5.10 PLEASE
Would love to see it attached to something like a scissor lift to observe how much useful work something like this can actually achieve. Robotics is interesting, but there is an entire world of more common workloads which require something along these lines. As such, something like a scissor lift is applicable to a variety of related workloads, such as solar trackers or simply lifting a load.
Make a screwdriver 9,5Nm should be enough
Hey mate, I haven't read through all the replies but this might have already been covered. Yes, your test rig had issues but I wouldn't be worried about inertia so much.
First off, before testing again be aware of your limits, if the gearbox is the limit then that's fine, it'll just break. If the GBox holds up then your current draw will max out in an instant and you'll blow an esc or a lipo, whichever has the lowest current handling capacity, that can get expensive, dangerous, both. Maybe throw a cheap automotive fuse inline.
I'd lift a load, essentially you just make a winch and keep adding weight until you can't. You just make the drum a known diameter and you can get meaningful results.
The problem with your torque measurement now, is that because of the high velocity you are coupling a significant amount of intertia. The motor inertia might seem very small, but because of the gearbox it is amplifier by n^2. None of the cheap brushless motors actually quote rotor inertia, but generally its somewhere around 30 gcm^2. That means that with your 64x reduction gearbox, you are dealing with an inertia at the output of about 0.0123 kgm^2 (note the change in units). Guesstimating the speed of the output shaft, its probably around 0.3 rotations per second, 1.9 rad/s. This results in an angular kinetic energy of approximately 0.0217 J. Thats quite a lot of energy stored, especially if you want to try to slow it down in a very short period of time. Point being is that you are generally measuring much more than just gearbox output torque.
Torque testing should indeed be done at zero speed.
Also, are you aware that there are specially wound BLDC motors meant for slow speed operation? These quadcopter motors are optimized to work in a constant high velocity, but the ones optimized for slow speed are much more well suited for most robotic and servo tasks. You can easily find relatively cheap ones if you search for 'gimball BLDC' and similar search terms.
My thoughts exactly. Plus the rotating gear stages add their own inertial energy on top.
that is true for real torque measurements. But as a max torque measurement it is ok. It doesn't matter where the load comes from, but you can say, that the max output torque for the transmission is at least 9.5Nm without destroying the transmission.
@@thrownchance I disagree with you, shock loading is inherently different than static loading. Torques might seem torques independent of where they come from, but you are disregarding the concept of energy and how it is spread over time. The only thing that can be concluded is that a (single) peak of 9.5Nm will not destroy the transmission. I put 'single' in brackets, as you might exceed the yield stress and start plastic deformation or fractures, especially in the infill. Only a proper fatigue test would be able to tell you whether or not it can actually deal with these peaks without damage.
An example for the difference between shock and static loads with materials might make more sense. A relatively stiff material (such as regular PLA) will have much higher peak stresses in the material, which can lead to broken parts. Something less stiff like PETG bends more, hence spreading the same impact energy over a longer time thus lowering peak stresses, which means it might not break for the same impact as PLA. It however should not be concluded that PETG can take larger torques as these are (again) shock loads. It is very likely that for the example materials PLA can actually carry a larger maximum torque due to the higher yield stress.
Are you sure about the unit conversions? joules aren't a big unit, so 0.02 joules sounds small. As in, it's the inertia of a baseball that is moving at 2km/h (equivalent of falling a whopping 1.5 centimeters)
Definitely shouldn't be able to break the arm on its own, but I guess it could influence the result somewhat.
@@alexbv475 Yes I am sure of the unit conversions. As a double check: rotor inertia is 30g cm^2 -> 0.03kg cm^2 -> 3e-6 kg m^2. Adding the n=64 gear ratio: 3e-6 * 64^2 = 0.012 kg m^2. Rotational kinetic energy is 0.5*I*omega^2 = 0.5*0.012*1.9^2 = 0.022.
It might not sound like much compared to your example, but a baseball is 150gr, quite heavy. If you drop this from 1.5cm onto a loadcell, it too would produce high forces. The key problem is that you have something that you drop onto something very stiff. This means that a lot of energy has to be dissipated in very short time period, and thus peak forces are quite high.
A pillar in a carpark can sustain tremendous loads, but if you smack it with a hammer, which has relatively low amounts of energy, the high peak stresses will still allow you to do damage.
Really cool design, thanks for sharing! If it is accurate, that amount of torque out of a 3D printed gearbox is wild. +1 for adding an encoder for better low-speed control.
As you have concluded, measuring torque while using an ESC won't really tell you much.
There are some very nice alternatives to ODrive now that would work well with the size of motor you have.
In particular: the Tinymovr (R5) and Moteus controllers. They are much smaller than an ODrive, come with the encoder built in, and mount directly behind the motor.
Literally cheaper to buy the equipment to design and build your own driver with an STM32
Wow, you could get an entire stepper with more torque and a much higher RPM than his motor+gearbox for less money than the >$100 controllers you mentioned. Seems like hacking an ESC that supports position feedback would be a much better idea
What I find most impressive about this quadcopter is the potential it has for DIY enthusiasts and makers. With the ability to design and print your own quadcopter without having to purchase expensive parts, it opens up a whole new world of possibilities for those interested in robotics, engineering, and design.
You could try testing how much weight the gear box will lift at given ratios. Knowing that would help determine what kinds of applications you might be able to build this into. Long Term speed test for heat and wear would be good too.
Isn't that what torque is?
No the problem is the motor is too fast. Unlike a theoretically optimum electric motor, it can't produce 100% of torque at zero speed. It can only produce torque well while moving quickly, he explained that. A sensored motor is the solution.
The major blunder in the test comes from the fact that when the shaft is stopped in the load cell, the motor stops, thus we don't det the stall torque but instead the torque necessary to annihilate the angular momentum of the motor's hub, shft, planets holders, planetary geers, ... everything that spins gets some angular momentum to annihilate with a counter torque if you want it to stop
There is no "stall torque" to unsensored brushless motors. Just like normal internal combustion motors - they only produce torque when rotating at a decent speed. Controllers use back-EMF to recognize the phase switchpoints and when the rotor is stationary - there is no back EMF. ESC sends some impulses to start the rotation, but they are random and weak, it just twitches around. This was perfectly explained AND demonstrated in the video, by the way.
This gearbox is one of the better ones i've seen on YT! Good job. Btw since you can't do a static torque test, it would be nice to see what weight it could lift at a given radius. For example, build a simple drum with 50mm radius with a string attatched to some weights. Then you could try different weights and speeds.
Also, this would enable dynamic endurance testing which would be really interesting to see.
And, maybe even try different filaments. Maybe nylon or petg as gears?
Great design. You are measuring 9500N of force by the load cell however, your load cell has a max capacity of 200N!
???
sarcasm?
Do a weight test with the motor, like put a pulley on the end of the motor and a string/wire and keep adding weight until something fails.
Why do people who use 3d prints often dont use any oil or lube for gears? I see it so often that they push bone dry gears together. But respect for the build!
A quick way to electronically reduce the speed and increase your motor's torque is to desolder the connectioms to the three phases ( at the stator) and rewire them in a wye configuration if they are currently wired as delta. This will cause current to enter one phase and be forced to energize an additional coil on its way back out of the motor. The scope of this mod is to reconfigure the phase connections from parallel to series. The motor will have more energized coils at any given moment, thus increasing its torque. I've used this trick before with good success and my motors live longer and run cooler. Keep in mind that you will decrease the maximum speed. That is the tradeoff.
That 3d printer is amazing. I've never seen print quality/ such a small bead from the nozzle in a hobbyist's printer.
Planetary gearsets are 3-way adapters for gears. This design uses 1 of them as housing, and the other 2 change ratios like a car transmission. An old-fashioned manual transmission could do this more simply, or an Allison transmission is more elegant. Or add another motor (it can generate too, right?) and just 1 planetary gearset and you have a hybrid transmission. All 3 of those are modular designed to change while the vehicle is in motion, without having to stop and bolt in other parts. But this is a good learning exhibition - a launchpad to talk about transmission designs. Thank you for making the video.
Just mount the arm with the load cell to the gearbox case and mount a longer shaft to the output shaft, so you can grab it with a glove to apply a breaking force to the output shaft. Now you can do continuous torque measurements at different rpm's without the influence of inertia!
Amazing project, you tested, you printed, and posted the step files. Is a proof that you really know what are you doing. I enjoy your engineering projects. I will use this gearbox as a sailwinch for my rc-sailboat. Let's close loop this marvel.
You were asking in the video for better methods of measuring the torque capabilities. Automotive actuators are tested as following:
PULL OUT TORQUE: Mount a weight on a lever that hangs straight down before the test. The motor then tries to raise the lever as high as it can. The further the motor turns, the further the weight is away from the vertical axis and the more counter torque it will see. The limit is called the pull out torque, which represents the counter torque it can handle during movement.
PULL IN TORQUE: Mount a weight on a rope winding and lift the weight with the motor. The weight does not change over time (if you ignore the diameter of the winding growing with the rope winding up), but by making the weight heavier you'll find the limit of torque that can be applied from still stand.
The pull in torque is also a nice automated lifetime test if you want to measure the durability. The gears will be worn only in one direction (counter torque does not change direction). Take an Arduino to generate a servo signal for the ESC, this should automate it easily. Be aware that you also test the capabilities of the ESC: their behavior when detecting blocking is a pure software thing.
you should try using a stepper motor instead of the brushless drone motors they are terrible for low speeds they have to be above a certain rpm to achieve maneuverability
Brushless motors do not normally actually have a sine-wave drive. It's actually more efficient to use a trapezoidal wave, and hence what most ESC's use.
Wow, thanks. One or two weeks ago I designed planetary gearbox for 5010 myself but I didn't get to assembly. It's nice to come across same idea, u saved me couple of hours of tweaking. Thumbs up!
Thats a really cool design, the rotating planet core that is just one free spinning stack of gears is quite fascinating. -1 for the torque test, because the peak is highly influenced by the inertia
use simplefoc to control the driver at low speeds, even without encoders. it works great, and can be upgraded to encoders. there is even somewhere a board which lets you do a control by amperage
The stm b-g431b-esc1 is capable of doing basically everything, but it is a hassle to work with.
These would be perfect for hub motors in a build. I could definitely see this being extremely beneficial.
Nice design. with a few slight modification in particular of the end piece you could make them stackable and destackable without requiring reassembly of the individual modules.
This gearbox could be scaled up and used with a 40v lawn mower motor for a DIY ebike conversion. Motor input speed is 3000 rpm. The gear box output speed will need to be 300 rpm. The final drive reduction to 70 rpm can be achieved with a 12 tooth to 52 tooth chain ring on the pedals.
Really dumb idea considering how fast a BLDC motor can go, but what if you connect the motor to the output to backdrive the whole planetary system (i.e. instead of 64:1, make it 1:64). As GLaDOS would say: "Speedy thing goes in, speedy thing comes out". Doubt the small motor could keep up, but would be fun to see how fast you can make a thing spin on 1:1, 1:4, 1:16 and so on and see where the point of diminishing returns kicks in.
Great design, I am in the process of automating my pool, and these gearboxes will be great for automating the valves, e.g. I can automate the flow to bypass the solar heater if the pool temp is too high, or remotely control flow distribution from pool to spa, etc. I'll probably be using steppers and arduino IOT. Thanks for your community spirit.
Applications:
Mechatronics, like robotic grabbers, RC crawlers... You could make some wild automated kitchenaid mixers, or dough machines, cutters/log splitters.
The gear box could be used in reverse to make a gravity battery. Weights unspool, turn slowly spinning a motor quickly, creating power.
Absolutely mind blowing. One of the simplest gear boxes I've ever seen. Thanks for sharing :)
This is really cool design. Prints pretty easy too. Fantastic work.
4:09 I think you should put some engine oil or grease to lubricate those gears so it will not sound loud and will work smoothly ❤.
Also gears will not wear out.
The Jim Lahey clip earned my subscription Sir. 👍
Another idea may be using different motors on this gearbox (Brushed DC, Stepper, etc), and perhaps making different mounting plates, but the core+output being a “universal gearbox”of sorts.
0:52 "+/-/Magic?" Love the humor! Subscribed! 😂😂
The most impressive part of this video isn't the gearbox, but the fact he used a bone stock CR10 to do it!
great and simple one, easy to mount....thank you!
Ill try using it for a powered cart for hauling stuff around the garden
You have too few subscribers, this is an engineering masterpiece.
Bir mühendisin espirileri yine başka bir mühendise çok iyi geçer :)
+ - magic😅😅😅😅👍👍
Nice job designing and printing !
To really measure the torque, you could use a pulley as an end shaft, and try to wind a cord around the pulley while refraining the wire with one of those luggage weighting hooked, until you stop the motor. So you can get rid of the starting couple & the inertia 😉
it makes me unconfortable how good your ender 3 prints
Put a spool on it and lift weights. Moment arm is radius of the spool. Lift a plastic jug and keep adding water. When you can't keep motor RPM you hit the limit.
I think what's missing is the ability's to hot swap out the reduction.
Maybe a inner shaft that engages only at selected ratios controlled by an outside sliding mechanism, or the rings could twist lock into place with a manual switch to unlock a retractable back stop where said rings bottom out on the previous one.
The going brushless bit floored me🤣🤣🤣
INSANELY ACCURATE LINIER ACTUATORS
Dude you’re so funny, the edits caught me off guard a couple times hahhaa 😂
Waw, really amazing ! No go and build a robot arm with this !
If you want to test the torque, I'd print a drum with a string or rope attached, and have it tug on a drag scale, or however they're called. Then you can have the motor run at 100% and void the intertia aspect of your current test
+1 for integrating a sensor and odrive in a future video. I'd love to see what kind of torque is possible to get out of these low-end BLDC's with 3d printed gearboxes. This is a great video. Keep up the excellent work!
yeah it would be great to see how far this could go!! keep up the good work !
Nice work!
I'd like to see a helical version and a backlash test. I could see this being great for joint control with a sensored motor.
Herringbone would probably be better so they self align.
This has a great application for a trolling or outboard motor for boat. At least that's what I'm investigating
You could try using a disk brake off of a motorcycle or even a bicycle to create a torque dyno to get more accurate torque readings at any speed.
Says it feels very smooth as the GB siezes up
holy crap, you're using a TI n-Spire! That's cool!
You could make a shredder and use the gearbox for the shredder axis to see if the torque is sufficient to crush plastic parts (it could aldo be a cool thing to watch)
This guy needs more subs! Awesome content
What about using it like a wrench to pick up weights. Can that be a more accurate measurement of torque?
Mount it to a mountain bike brake disc and then add the load cell to the caliper. Will allow you to measure the torque while it's spinning
Great video, as always!
I think you can reduce a lot of the sound problem if you build conic gears instead of plain ones, they are more efficient in high speeds too.
Man I wanna make this on a industrial level, compact modular motor it could be revolutionary on repair and replacement in the field
I’m building an Astromech and curious if this could be incorporated into it. I’m still learning about the mechanical and electrical engineering involved.
I'd be really interested to see a similar thing but with different combinations of gearbox modules with different reduction ratios. With this, you could design a clutch mechanism that disengages the gearbox modules so you can get a variable gearbox out of it.
1:04 I paused this video to watch a "normal motor vs brushless motor" video. I wish I knew you were also going to include the explanation in this video. :-)
I might be wrong.. but it looks like it would fit 5 sprockets. A downside to having even numbers is that the force is straight in the gearbox.
I would also cosider to make the first two half the thickness, if not less.
Add some more gearboxes and make a car winch!
Actually a tracked vehicle would be cool. The gearboxes look quite good at keeping dirt out so may be good off road?
Congratulations! you made another screwdriver)
We wonder if this could be modified to have a bevel gear to drive a tail rotor mid point in the stack. For a RC helicopter
I'm thinking about using a planetary gearbox to make a spindle for my homemade cnc mill. It cuts aluminum just fine but I need more torque and less rpms for steel.
"3 wires? That's kinda scray." instantly subscribed bro I love your humour
Another idea could be using different gear profiles, but an otherwise identical format. Could maybe try and get a series going akin to that “Design a Fan Blade” series although I don’t know how to build that hype i guess!
Herringbone Gears are the ultimate if I remember correctly, although there is probably some downsides i am forgetting.
Among other things mounting the gears requires split gears, twice as many housing parts, requires more dexterity to put together; not insurmountable... Much quieter, more torque, many advantages!
It would be fun to slap that onto a bike and use to ride around. Would need to change the design to either add a small prop for air flow over the motor for cooling, or a duct and a blower motor.
Have you tried to make gears by printing cylinders on which you stick a kevlar belt?
Used your amazon affiliate to the materials for this build. Thank you for this amazing build.
Nice grinding gears sound!
this is AMAZING MEN !!!!!!!!!!!!!! 🤩🤩🤩🤩🤩🤩
Love the trailer park boys clip!
I see any Mr Lahey reference I hit that like button.
Loving the How Ridiculous reference :)
Nice work! It would probably be strong enough to open and close a good-sized gate...when the cows come home :)
Great design, I would be interested in the backlash of the gear box.
If it is almost backlash free, I could use the design for a 4th axis in my CNC machine
Haha! A TPB’s clip! I’m a fan right now.
It would be neat to see it taken to the extreme where the final output has such an incredibly high reduction that it can be embedded in something unmovable and still function. I remember seeing a similar setup where the output was embedded in concrete but it will functioned because the extreme reduction summed up to basically no movement on the out put. Wonder how many reduction gears you'd need to achieve something similar.
you could make a simple dynamometer by introducing a clutch between the output and the load cell so that way you would get it's dynamic torque.
Do you have any crank windows in your house? How about an automated window open and closer?! 😁 Great share, thank you.
Couple the gearbox with a block and tackle system to raise a car?
im actually going to pick the files up and see if i can put them in any of our machines to see how well it holds up against actual mechanical force compared to raw movement
will take a while but ill let ya know
Maybe igus i150 or i180 filament to reduce friction? i180 is a bit harder to print without chamber.
is it really necessary to have the outer shell have gear teeth on the wall? maybe it makes sense for stabilization but it feels like youre adding unnecessary friction. i would model the walls to lock with the motors so the motors stay in place but the gears down scaling your ratio could benefit from removing that extra friction happening with connecting with the wall gear teeth... just a thought
U need to get a sensing esc. So it doesnt stop adding load.
you should use a stepper motor and try going 1:64, and see how fast you can get one going before it blows up
I've seen a lot of videos doing Gearbox but...
What are they for?
There may be potential to use the output as an input to use as a generator
3:44 very smooth indeed
An involute profile on the teeth should help your noise issue. In addition, it didn't look like there was any backlash between the gears. For something that small, the backlash would be extremely small. .001 inch backlash would be more than enough, but hopefully not too much to cause some issues.
I'd look into a liquid lubricant. Most planetary gearboxes take oil, not grease. Might give you a bit of a bump in efficiency!
A truly masterful design
"feels very smooth"
*crunching noises*
You forgot to include a link to the plastic/wood counter sunk screws you use to secure the outer hub
Love to see this ..converted to magnet gear box