3D Printed MTB Inner Gear Drivetrain | Trampa Holypro | VESC 6 | OVERION 130kv | Graphene 12S12AH

Unfortunately not yet, I only rode it once in the dark so far. There are too many things lift to do/print for a proper maiden ride. But I might try again on the weekend if I manage to print the gear covers.

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Today i did the first little test ride on the street. I’m very pleased with how the board handles, just needs some tuning on the throttle curve (as in it accelerates too bloody fast (which is how i wanted it but still)).

Still no Enclosure for the Drivetrain and the Electronics, but i updated my Motor Mount Design. On the left is the old one which, in retrospect, wasn’t too brilliant especially the placement of the grub screws. It resulted in the motor being not parallel with the truck. The new design fixes all that with a double grub screw on the opposite side of the motor.

My current roadmap is to try and make a cover for the gear, looking something like this and using some sort of sieve to cover the rest of the exposed parts.

And finally a enclosure for the electronics for which i already printed the bottom part, currently hesitant to print the cover because i can’t decide on a design for it.

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Do you think you can help me with modeling the Pulley correctly? I measured the belt teeth when I made my Pulley but the grooves don’t match up perfectly.

Sure, hit me up

Just for your information so can you find files of HTD 5M (most likely What you use) profiles on thingivers. You can just bring these STL files in to your cad and work from there. :grinning:

So today i made the first multi-kilometer trip with the board on all kinds of surfaces. Started with a short ride on the street - massive improvement over the longboard because of all the potholes here. Then went on a path with a lot of gravel and small rocks. Board handled it excellent but definitely not my favorite riding experience. After that i got to a place with trimmed grass and it was just great. Such a soft ride with the pneumatics and the deck.

However one if my gears drive began to rattle whenever i was braking or applying no power. Found out that the Motor Mount became loose even though i just applied loctite before the the ride. I don’t know if that was the cause or the symptom of the rattling. Will try again, if that doesn’t work i will have to redesign the motor mount with m6 instead of m4 grub screws and narrower tolerances against the truck.

Still no sign of wear on the gears even though i was making sure to torture them hard :smiley:

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How “just”? loctite needs a few hours to cure

Looking forward to hear how long those gears last

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Ooooooooooooh. Then it might work better tomorrow, thanks! :sweat_smile:

I used the regular blue stuff.

Pretty optimistic by now, I hope it’s justified :slight_smile:

So that’s it probably, but i don’t know how well it works on plastic, maybe not at all, it may even dissolve the motor mount a bit, if that not work you can try MEK (methyl ethyl ketone), its the best thing to glue ABS, just dip the grub screws and insert, give a few hours, it will melt the plastic on the thread and give a pretty good bond, if all fails, just a tiny drop of CA glue

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Thanks for the detailed answer, it will sure come in handy in the future with 3d printed projects! However for the mounts I’m using threaded inserts that I molted into the plastic so there’s no reason Loctite shouldn’t work.

And I might be able to further reduce the gap between truck and mount so it sits more snugly by default without screws.

Oh sure, where did you buy the inserts? a few months ago i needed them but couldn’t find

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Uh I just got them off eBay, they are called Rampa Inserts. Can’t say anything about the availability outside of Germany. But generally they are made for wood applications.

I made holes in the model for them (around 1-2mm smaller in diameter than the outer thread of the insert) and put the inserts on my soldering iron tip and screwed them in with it.

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Thanks, I will see what i can find

So TECHNICALLY i got the first gear failure today, however on this particular gear the printer fucked up before. During the print some layers weren’t fully extruded which is why the gear seperated in the middle. Originally i filled up the gaps with some glue and it held well until yesterday but i guess it wasn’t enough. Bummer, i can only print these 12 hour prints on the weekends when im home.

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thats fine for a prototype i guess. i would print the final gear in nylon anyway and you have to print nylon so ridicoulus slow that underextrusion probably wont happen there.,

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I’m quite satisfied with the Polycarbonate/Nylon print and i guess the underextrusion happened because i tried to keep the filament in the original box while printing (because of humidity). Stupid mistake, i will probably print a better spool holder for the next time. I really need more printers for prototyping :sweat_smile:

But still no wear on the other gear!

what filament are you using right now?

Still using Alloy 910 for the gears and PLA for the mounts

I printed some nylon motor pulleys (pretty sure Taulman 645 is what I used, was either that or bridge, the amazon link is dead) You definitely need to dry it out like crazy in a toaster oven that isn’t used for anything else or dehumidifier for a good amount of time before using it at all, the steam in there really makes the layers weak compared to a completely clean print.

You also want to go pretty hot and really slow, like @Achmed20 mentioned already slow is your friend when it comes to nylon but that also makes it terrible for printing big parts. Personally have started taking my 3d prints and making molds of them using silicone and then pouring resins into the silicone mold to get a solid part, it adds a few steps but once you have the mold it’s much faster/easier to make solid parts and can choose from a variety of hardness plastic/urethane resin mixes to pour into the molds depending on what exactly you’re making. Have been using this 85D hardness stuff called task-9 for some wheel pulleys but have only done hard bench testing and light on the road testing (been too cold to go ride much recently).

Custom wheel pulleys Nylon motor pulley

Nylon motor one held up for a couple of months of riding, but that was the best one I’d made the other attempts had delaminated in different ways (either through the grub screws or internally so the motor would spin free).

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That was an interesting read, thanks!

Originally I was also looking into pure Nylon like 645, but on the Taulman Website they say that Alloy 910 is for high load gears, opposed to medium load gears for nylon 645, which is why I chose 910.

I do keep the filament very dry at all times and I hope that this isn’t causing the issue, after all there’s also a good part of polycarbonate in the filament which should be less prone to humidity than nylon.

I print with 250°C/60°C at 50mm/s and the printing process itself looks pretty ok. Just had to tweak retraction a bit, but that doesn’t matter that much for gears.

The gear delaminated right at the point where the extrusion failed and where I later applied glue to hold it together for a while at least, so I’m pretty confident that the teeth are strong enough for this application. The glue just wasn’t enough, there were parts in the gear that you could look through so the layer bonding was barely there at that point.

The mold making sounds really interesting, I will definitely check that out a bit. It’s really a pain in the ass to print 12h for a single gear so I’m very open for different methods.

Personally I wouldn’t use plastic parts on the motor pulley so I’m impressed you got it to stay on there at all :smiley: I’m using regular steel gears on my motor shaft.

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