Broken Pulley - 3D Printed

I just recevied my 3D printed pulley for my flywheel clones, however, when I tried to push them in to the holes, two of the ‘legs’ snapped off and another snapped but is holding on by a thread!

Has this happened to anyone else? Is there a special knack to getting them in? Are you supposed to heat them up first?

Any help/advice appreciated…

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This happens to me when I had the cooling fan too high during the print so the layers didn’t mesh properly. They should push in with a small amount of force

Also I recall you saying you have a MK2S? If so why so much over extrusion?

To be honest, it wasn’t going in so I pushed it quite a lot, then came the snap! :frowning:

Yeah print settings were probably off. The pulleys @JuniorPotato93 designed push right in.

This one just seems to be a push-fit, no bolts or anything, how does that work then? Does it just stay in with friction?

The enertion pulleys are just push in as well no bolts etc but obviously not 3d printed! Occasionally have to push them back in slightly but they are a very snug fit.

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Slightly off topic, but what filament do people recommend? Does ABS work or should I go with some PC or Nylon filament for durability? That is to ask, how much durability is actually necessary to ensure teeth don’t wear too quickly.

Thanks for that. I’ll see what this seller comes back with, hopefully they’ll just send me a replacement.

I may think about just removing an opposite ‘leg’ and screwing bolts through from the other side in to the nylon.

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If fitting them takes a bit of force to install then they will normally stay in place! Iv found the best way to do it is to push the pulley in to the wheel slightly then turn it over,lay it flat on the ground and push down on the urethane wheel with your palm/s till it pops in!

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Yeah that’s kinda what I did with this one just before it went snap! :frowning:

I think, if I get a replacement, which I totally should, I’ll heat it up with the gun a bit first then push it in. At least then it’ll be more pliable and then harden in place.

Yes they should be push fit. The print quality might be an issue since it looks kinda rough. I printed my own and they fit perfect within my flywheel clones

@darkkevind you could anneal the pulleys before you fit them to gain strengh. Annealing plastic involves gently reheating the substance to a point above its glass transition temperature but below its melting temperature and then slowly allowing it to cool. Like the annealing of metal, this reheating and cooling increases the amount of crystalline structures in the plastic.

Yes, that’s what I’ll do just before fitting them, not too much though because I don’t want them to misshapen whilst pushing it in…

I would do it a few times before you fit them if your using 3d printed parts,an oven is best,just don’t go above the melting temperature of the material used.

The glass transition temperature of PLA is 60C to 65C (140F to 150F). It’s melting temperature is 173C to 178 C (343F to 352F). Therefore, you want to set your oven temperature to about 110C (230F) when annealing regular PLA.

The glass transition temperature of ABS is 105C (221F). It’s melting temperature is 210C to 240C (410F to 464F). Because of this, you want to set your oven temperature to around 100C (210F).

The glass transition temperature of Nylon 12 is a surprising 41C (105F). However, it’s melting temperature is a respectable 178C – 181C (352F to 358F). Because of this, you want to set your oven temperature to 130C – 140C (266F to 284F).

@darkkevind hope this helps :smiley: Edit:don’t use a gas fired oven!

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Nice! Thanks for the info mate! :thumbsup:

FYI, it’s nylon apparently.

Just wanted to add (good post already) that Nylon comes in a huge amount of varieties so different ones have higher temps (some variations in PLA or ABS but not as wide as Nylons it seems, the 645 type I had prints at 250-255C so requires an all metal hot end).

Having an enclosure around the printer helps a ton with keeping everything above the glass transition temperature so you don’t get the warping happening as much while it’s printing but will still get shrinkage after the fact depending on the materials used (ABS warps quite a bit, Nylon more, PLA barely warps at all even without an enclosure). For any eskate stuff I’d say only ABS or Nylon are choices, ABS will likely break down over time, Nylon is super durable and has a pretty slick surface so likely won’t wear as much from friction (Nylon injection molded parts are used in drills and other power tools for gears, 3D printed won’t be as strong as injection molded but still pretty good if you go high infill you have almost the same thing)

Downside with nylon is try printing anything bigger than a pulley and you’ll have a hell of a time, it has to be printed slow and the filament has a tendency to clog up if you have too high a retraction (too low and it oozes strings between everything that need to be cut with a razor). For small parts as far as I’ve seen you can’t beat it.

Also I do use PLA still since it doesn’t warp it’s a good base for making a mold and then can pour solid parts out but the silicone for mold making is pretty expensive and not always obvious how you should make a mold for something you can easily 3D print.


Thanks, that’s good information.

To be honest though, I’m not printing these, I don’t have the foggiest Idea how to 3D print and don’t have a printer, I just bought this pulley off of ebay…

If anyone else (in the EU) could print me a good flywheel clone pulley that’d be awesome? lol

Heh yeah just figured I’d add for the topic in general on 3D printed parts.

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@wafflejock your right there are a lot of variables for nylon,I just don’t have time to list them all lol I would just use these as guidelines,most nylon 3d printed parts shouldn’t melt at below 140°

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I wish you were in the states, I’d print you a set free. I print them with ABS at 100% infill. They are a tight fit but I’ve never had one break other then when removing it from the wheel. I use a modified version of the @JuniorPotato93 wheel pulleys that I made a few months ago. You can see them here.