Testing 3D Printed Stackable Gearbox
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- เผยแพร่เมื่อ 19 ต.ค. 2022
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This 3d printed gearbox way outperformed my expectations! I think it can even be stronger with some minor design and printing changes. Let me know if you guys have any recommendations on ways I should test or use it. Thanks for watching!
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The modular design is great - even for repairs. But the forces increase with each stage, so the size of each stage should increase, too. i.e. the planet carrier on the last stage could be bigger and stronger. I could see your design getting used IRL. Obviously you are a mechanical engineer.
I agree with this suggestion 👍🏽
Or print the later stages in different materials. This thing printed out of glass-reinforced nylon would probably be more robust than a drill gearbox through sheer cross sectional area alone.
@@namAehTyeah, except that fdm 3d prints shear easily. Unless the layers are melted together
One pretty easy and cheap way to increase strength around where bolts are mounted in 3d prints is to add metal washers imbedded into the print, it helps spread a lot of the load out across more distance and gives a strong metal back.
Planetary gears need to run on a through shaft to a backing plate. By constraining the shaft on both sides you will reduce the lever action on the carrier plate. Longer gears will just make this worse. as you will be increasing the lever length.
This was so taking me back to my previous work as a mechanic for Barloworld, South Africa's CAT dealer. We have had so many failures in planetary systems that i cannot even tell you how many.
I think that you are on the right track with identifying the output carrier as your weakest member so trt printing it in the strongest material that you have available.
This will unfortunately lead to the next weakest item failing and so on.
The idea here is to place a limit on the amount of torque that you want to have go through your planetary reduction drive as you can keep over engineering all the items ad infinitum and never reach a point where you are satisficed.
If you look at your different CAT machines using planetary reductions, they are all designed and sold in different size and application markets, from handyman to relocating mountains.
I really hope this helps as I am just a retired earthmoving mechanic on medical pension.
Pieter (Pete)
A double sided carrier near the output might help. Also as others have said, longer planets and even potentially a larger pitch ring gear/planets.
You can get those same battery connectors in "anti-spark". They have a built in resistor. Saves the arc damage on the connector and is less stressful to the ESC. I love these gearboxes. Awesome work.
It would be interesting to see it printed in nylon, preferably with glass or carbon fibre to reinforce it. Also it should be printed at 100 % infill. With the nylon you could test it just after printing but also after letting it absorb moisture from the air to see which is stronger.
Heat set inserts are great, I am surprised they aren’t more common, they are so easy to insert and they are pretty strong, but it seems a lot of people don’t like them or are scared of using them. I was printing the matterhackers E3D V6 mount and found one that didn’t use threaded inserts and it required very specific nut shapes and sizes to insert and specific length bolts, whereas the matterhackers one that needed heat set inserts was very easy to put together and just used the inserts I had anyway.
Cool video. I think one of the easiest improvements is turning the carrier into a cage like design so the planets shaft is supported on both sides.
I haven’t gone through all your videos so I’m sure you’ve done this before, but I would love to see you do pre-test analysis to predict failure. I think it would be a great learning experience to see how systems are modeled and remodeled iteratively to match empirical or experimental results.
Great video, Mike!
One thing I noticed was that the planet gears spun concerning the carrier. This is indicating that there is too much force on one side of the planet gear for the carrier to handle. Putting another carrier on the other side would not induce a force on that side to help but may distribute the offset across the planets. Further, there should be enough room between the planet gears for the carriers on either side of the planet gears to be connected. The force could then be given to the planet gears from carriers on both sides and reduce the incorrectness of the torques on the planet gears.
Very entertaining thank you. I’m learning so much from your projects. On strength in plastics, it’s generally good practice to design out stress with radii and chamfers, especially for structural loading. The bigger the radius, the better distribution and transfer of stresses - minimise notch fractures.
One word, genius 👏
Very interested to see how this plays out!
The planetary gears are tearing out of their mounts, because the tolerances are loose enough to induce end-climb. Add a backing plate for the far-end of each gear shaft, or switch to double-helical teeth, to minimize the end-climb, and compensate for the wide tolerance. And if you are using lubrication, add a center-channel valley. Experimenting with its depth will allow you to "leverage" some of the hydraulic lock to your benefit, as it effectively reduces the tolerance problem that is causing end-climb.
Thank you for CAD and STL files.
Amazing design!
Im extremely excited for the next video!
You know how I know you're a good person? Step files. Bravo.
make that gears and carriers longer the more torque that are applied to them. First stage 1x, second stage 1.4x, 3rd is 2.2x, last of the four is 5x long
With my carriers I have a screw that acts as a center shaft through the carrier and this way there is some metal reinforcement at the core of the axle that goes all the way through the part.
You should make the carriers double sided. Run a web up between each gear so its inside and outside are still clearanced, but support the gears at each end. That should help.
Love it. Just subscribed. TY for sharing.
Heat set threaded inserts changed my life and the way I design prototypes man. Also, barrier to entry for CNC milling is pretty low. (Relatively, I have a CNC machine shop already) You can get a genmitsu pro for pretty cheap and with some mods to the backlash nuts it will most certainly machine aluminum. You can also solid print the bearing backings combined with the housing to give extra support to the pinions.
As far as improving the planet carrier, one thing that can be learned from impact drivers is that they capture the planet gear pin on both sides;
What that means is that there is a second plate with a hole in the middle that restricts the movement on the ends of the pins, stopping them from twisting side to side.
Usually the carrier is made from a single solid piece, which should not too difficult to 3d print.
Amazing design. I have to get a 3d printer! This would be so much fun
The spark connecting the batteries is a classic in the solar / off-grid community, you should add a switch and do the plugging while the switch is off, to limit the sparks.
Great video, i've been looking at those motors for a few months now and wondering what the performance would be like,. When printing gears I found that strength is usually won by the layer lines over infill, so for the smaller gears maybe a 12 layer line. Polymaker Tough PC Filament we've used one a couple of the robot builds, on gearing especially. There is an annealing process with that filament too, so pop it in the oven for a few hours which will aid on the compounds to become stronger. Love the video !
yup. heat treat the prints will help with max strength. there are some test videos online.
@@jpjay1584 thanks for the reply a year later lol :)
100% infill with Nylon or Nylon with carbon fiber content. Or with more classical materials: print a positive on the resin printer, make a negative from silicone, and cast a positive from polyurethane resin.
I've always wondered if you could make an plastic 3D print stronger by leaving vias in the infill and pouring an epoxy resin as used in fiberglass. Think of how rebar is embedded in concrete to give it extra strength.
Very impressive !
This was excellent, thank you! Can you link your motor and ESC in the description along with the design? I think I may want to follow along at home, so to speak. :)
this gives me ideas
The fact that you didn't already print it at 100% infill is a lol moment. Great video!!!
You could have the planet gears supported from both sides by having a bottom layer with large enough hole for the output shaft of the previous stage to pass through into the next stage, should help against the twisting load on the planet gears.
awesome! great work!
Nice project! You could try to print the planet carriers with PLA Carbon, also 100% infill seems a good idea. Bump the extrusion temp as much as possible for the material. Usually it makes the bonds stronger.
As well as salt annealing forsure
Impressive!
Would be interesting to see how machined aluminum with this design would hold up or some different metal
if you add some potential energy, then convert to kinetic energy to the dumbbell (by dropping it in to your sensor), you will have a complete different measurement. That's what are you doing when you measure the torque output with additional kinetic energy. Either way, there is no plastic gear match for this motor, unless you make them very large and introduce even more problems. Plastic gears will get destroyed with or without stored kinetic energy.
Excellent
I like the gear salad at the end!
Love your videos! Looks like there may have been some layer adhesion issues, no? Maybe print slower, with slightly higher temp. Or basically, don’t rush the print. Idk. You the man bro!
head on over to the torque test channel where they show Milwaukee's impact planetary drive system. They recent faced controversy where they redesigned the drive to a single shear support for the planets - and the mechanism kept breaking out of the box. You want to go with the tried and true double-sheer design which encases the planets and has bearings on both sides. This would make your system much longer per gear set, but will solve the carrier breakage.
Great experiment :D
Maybe the carrier could be thicker and the planet could be thinner… also choose a planetary with fewer teeth overall (to make each tooth bigger)… maybe the carrier axle should be a metal square tube or a pipe with threaded holes, so you can secure the carrier.
Finally, I have read that “annealing” does wonders in layer-to-layer resistance.
I also recently started using those heat set threaded inserts… don’t know why it took me so long lol
Great video. You want to select the aligned rectilinear/linear infill at 100% for best performance.
In Cura you have to manually adjust the line angle by typing the angles in settings.
Great work! Is this efficiently backdrivable?
Nice video, thanks
If I see that right you have the gears planet gears only attached to the carrier at one point each. I bet a lower ring connecting the gears on the other side could take a lot of those twisting forces. Also a shaft straight through all the stages to help align them could do a lot.
Agreed on last part. Stick a sanded 8mm rod down a hollow print with epoxy/glue
Thanks Bruu
Does it have a backlash? I am considering using it to drive astro equipment. Also, I'd assume it would be easy to mate this to NEMA 17 steppers?
An aluminium plate sandwiched between the planets hub, which also serves as the mount for planets.
PETG is less brittle. They say PLA is "stronger" but for gears PETG may work better. Also you want to grease the gears I think. pretty sure that's how they make gear boxes usually they put a bunch of grease in there. The PETG is higher temp too so if it gets hot in there (especially without grease) that would work better.
What is the general weight of this, was thinking of using it for prototyping
PLA is wayyyy stronger then the stigma everyone gives it. When I design my firearms I do so with bargain bin pla in mind and it always surprises people to learn that, especially that I'm make a 50 caliber rifle with it (on the top end of my designs).
Happy to hear that, because that's what I've been stocking up on lately, I've got all the colors now : /
TPU in the 75D range like ninjatek's armadillo seems like a good alternative to use on budget printers, when PLA doesn't cut it. Although gears probably need relatively heat resistant filament, especially when operating non stop, so budget printers could never deliver the optimal printed plastic gearbox.
PLA has one major drawback, and that is its susceptibility to heat.
@@graealex Yeah Its honestly ideal in most situations, but you get it even warm and its useless. (not good when using high power BLDC motors)
if your going to do anything in resin id advise you to use Siraya Tech Blu-Tough Resin. its really really strong
Very impressive, Michael. Any idea what amount of backlash is in the 3-stage drive? And of all the gearboxes you've designed, which design would you say has the most torque and the least backlash?
Thanks!
Kevin
5:36 now that was epic 😂
The carrier will be really strong if you use bolts that go into the shafts to compress the layers. The bearings should go on the plastic carrier's shafts, inside the shafts is the bolt which compresses every layer from the bottom of the carrier to the top of the shaft. Bearings aren't really necessary if you use lubrication. I made a much smaller 64:1 planetary gear box that uses no bearings. The carriers are practically indestructible.
This is a cool video, what I learned is I really need a quick 3d printer.
I was thinking of making a simulator setup for my pc and driving and flying games wonder if this might work on moving the seat platform , hmm?
Ok gear-man, if that truly is your name....haha. Great content! What do you suggest to keep high torque and some speed? Wanting to use Nema 17 to run the table on a mill. Thoughts? Thanks in advance!
you can print the planet carrier out of a filament that uoy can turn into metal
or just not
Awesome project! Just checking, the chart is taking into account the 100mm arm? So the results from the load cell should be divided by 10 to get the N*m.
cool. you most consider higher module for second and third stage
What kind of accuracy and tolerances do you get out of your resin printer
Htn25 and CFPC could be cool to try.
perhaps using heringbone gears for more even torque transmission?
How about having bored holes in the middle of the sun gear strengthen by thread rods.
Like this symbol Ꙫ , with them side by side.
Or even better, use some FHCS opposing each other screw in and held by nuts on each end. Hence, externally bind the 3d print layers together.
If you are able, you could try filaments with fiberglass reinforcing for the carrier, should take a bit more abuse.
Any way to put the plat gears in double-shear, with a second plate on the far side
Can you run it backwards to make a speed multiplier with the high torque motor?
Any attempt at making a faster servo?
Such as the previous feedback gearbox you made? But just a faster version.
First time using heat set inserts 🤨
What do all the other wood screw holes use
Electroplating the parts would be an interesting experiment.
Would it increase the peak torque?
Would it extend operating life through increased heat dissipation?
Awesome video (as usual). I'd be interested to see pure Nylon parts if your 3D printering skills & setup are good enough for it (warping might be difficult to tame). It's surprisingly rigid at high infill and basically indestructible (it will have to fail through deformation, instead of snapping/breaking). Nylon-CF would also be worth a go, but it's pretty abrasive so even if the gears work, they would probably wear down over time.
If it's all nylon-CF then the higher abrasion shouldn't make much of a difference. Also nylon is excellent purely for its self lubricating properties!
I'd love see how this would fare if you machined the parts out of steel. For that matter, since you have the 3D printed parts already, maybe make a mold and cast out of aluminum and see how much force it could take.
Honestly I wanna see this thing be upgraded to the max
What if you print the ring and planets at the same time so you could use heringbone gears (the ones that have v shape) for the support material you could use PVA so once first stage is done you can use water to remove the PVA
Any idea how long the gearbox would last under a given torque amount?
Thin piece of steel sheet on both sides of the carrier, with 100% infill 3D-printed carrier sandwiched in the middle. It wouldn't prevent warping completely, but it's likely the cheapest way to get more torque out of this thing.
Neat
Can you please update the parts list to include the new motor?
I feel like laser-cutting metal bits for the carriers might be your best bet. Or maybe ABS at 100% infill?
Good morning, did you manage to do this test with pieces printed in resin?
To measure torque, would have been easier to set it up as a winch lifting an adjustable/increasing weight? You could then also calculate speed at various loads (ie power). That way you are measuring the torque in motion rather than measuring an impact?
100% infill would be interesting, also sintered metal filament planetary gearbox ?
Great video! Are you noticing a lot of part shrinkage when the resin cures? For resin parts I have made in the past, I have noticed that mine can shrink up to ~5% depending on the resin, so I mostly stick to PLA for “functional” prints. If you are seeing shrinkage, how do you deal with this? Are you pre-scaling the size of the parts to be slightly bigger or are the tolerances in this design loose enough that this change doesn’t matter much? Thanks!
I haven’t really had shrinkage problems with the Siraya Tech nylon black resin. I typically just use the horizontal expansion setting in the slicer to get the fit I want between parts
@@michaelrechtin Nice! Thanks for the info. I will pick some up and try this out.
Micheal, great video! One thing about the audio recording tho, your clock cld be heard in the background haha it drove me crazy trying to find a clock in my room that is ticking but apparently its yours (,;
heat treat the prints and use herringbone gears. that should increase the strength significantly.
If you go for 100% infill, go for all walls instead of all infill. It's stronger
Aka 100% concentric pattern. Is this the strongest? I heard somewhere that 90/95% cubic/gyroid (depending on force direction) was the strongest.
@@dollarbutt typically not from what I've heard, since there's a higher likelihood that the layers from the concentric pattern are placed directly on one another which means it's more likely to be stronger between layers.
@@dollarbutt When you get to 100% filled, force direction means little to nothing. At that point it's all about how well the layers bond to each other. Else I would totally agree with you
… and maybe some over-extrusion to fill the last tiny gaps remaining, too.
Aligned Rectilinear infill is the strongest of all.
Maybe longer gears at the higher torque sections?
try Markforged Onyx Nylon if you can get your hands on some
I've decided to print it out and try.
Unfortunately in the outer ring, teeth are too close to the planet gears' teeth which causes problems with assembly and the whole planet gear rotates unnaturally and with great resistance.
Planet gears with sun gear works well and there is some distance in CAD files between them.
Have you faced a similar issue? Do you have other corrected or adjusted 3D files? Thank you for help, very nice project.
Nice experiments. Though I have a little comment - you shouldn't compare loads you've measured with rated output loads (like Smart car). What you got is a peak, but for a more meaningful results you'd need to keep the parts under the load for some time and step-by-step increase the load until a breaking point. Of course, that is more difficult test-setup, since you'd need transfer from rotation to the force gauge. And another parameter would be introduced - speed. You will get different torques for different speeds, which would mean to a lot more experiments needed. But don't take it as criticism, it's great when people "play" like this and those test results have some rough results too.
perhaps having more and smaller planetary gears would help more? Rather tired and thinking about how a bearing uses balls and such to minimize the contact to reduce friction considerably, so it could be that my thinking on the suggestion is flawed from the beginning, not counting the being tired portion
Just wondering, have you considered magnet driven gears? I don't know how long the magnets will last but at higher torques it will just slip preventing breakage I and increasing the life of the motor.
I remember seeing a 100 ton piston snap and threw hardware at the operators. Having a slip mechanism could have prevented breakage, replacement cost, and potentially of saved a life or injury, not to mention longevity of the part as no gears touch.
Granted regular magnets will not do 100 tons, 😂.
Have you considered a plastic injection machine for some of the parts?
Where can We find that big electric motor?
I want to see this in a bigger gear size to see if that would hold up better
* gentle words or persuasion *
ahhh, one of my people :D
Is that llldmax’s army green pla+ let’s just day I’ve also printed gears with that. Idk why I phrased it like that I’ve printed gears with that color of pla+ before. It was just like a fidget toy though