Press Fit Parametric 3DP Pullies/Sprockets for Kegel and Abec Hubs- Shelf Pin Enhanced!

[Qwiksand]

Here’s my take on the ubiquitous 3d printed pulley…

I’ve used bolt-on style printed pullies and sprockets for years now, but lately I’ve been experimenting with different custom drive systems and branched out into the word of press/push fit hub adapters. As you all know, 3D printed parts are fragile along the z-axis, fracturing easily along the layer lines. I found a cheap solution to this problem by incorporating these 5mm x 40mm Stainless Steel Shelf Pins to take the sheer loads off of the 3D printed parts.

I’ve included links to the Fusion360 files so you can experiment yourself- best part is they are fully parametric and there are both HTD-5M pullies and #25 chain sprockets with ABEC and Kegel hub adapters. The pins are smaller than the holes/slots in the hubs, so to get a snug fit I’ve undersized the pin circle diameter so the pins essentially squeeze the center of the hub for a friction fit. When sized properly, there is zero slop/play.

Let me know what you think!

More Pics

Download Files/Links

#25 Sprocket Public Link
HTD5M Pulley Public Link
Parametric #25 Sprocket.f3d (754.9 KB)
Parametric HTD5M Pulley.f3d (297.2 KB)

Changing Parameters and Printing Tips

All of my sprocket/pulley prints have been using 0.28mm layer heights. I’ve had great luck with PETG and PLA+ prints. Of course, I’ve got some Nylon printed sprockets and pullies that have lasted for hundreds of miles and many years as well.

Go to “change parameters” (fx icon) in the modify drop-down menu and you should see this:

Teeth- change this value to whatever number of teeth you need for your sprocket or pulley

KegelPCD- this is the pin circle diameter for the kegel hub adapter. Kegel hubs are generally on a 1.25" PCD, but we are using undersized pins so the PCD in this part will be smaller- adjust as necessary for the fit you are looking for

PinHoleWidth- diameter in mm of the hole for the shelf pin to press into, I’ve had great luck with 5.1mm when printing at 0.28mm layer height utilizing PLA+ filament, you may need to adjust to suit your printer/filament

PinHoleDepth- how deep the pins are set into the hub (only used on the HTD5M pullies, sprockets have through holes)

HubOffset- this is the distance from the bearing to the outer most face of the wheel- most wheels I’ve been using are between 12-14mm, but adjust as needed

PulleyThickness or SprocketThickness- width of the pulley or sprocket

PulleyOffset or SprocketOffset- distance between the inner face of the pulley or sprocket and the wheel (used to give chain clearance mostly)

HubDiameter- width of the largest part of the printed hub, rarely adjusted

PinLength- the shelf pins I’m using are 40mm long, but maybe you need a different size

AbecPCD- this is the pin circle diameter for the ABEC hub adapter. We are using undersized pins so the PCD in this part will be smaller- adjust as necessary for the fit you are looking for. Please note I’ve only ever used “clone ABEC” wheels, actual ABEC11 brand wheels will almost certainly need a different PCD.

[Venom121212]

Very cool project!
Thank you for sharing

[EreTroN]

Have you actually rode this? How does it feel?

[Qwiksand]

Not sure what you mean exactly…these are just
wheel sprockets/pullies- feels like any other set-up I’ve used. You have to have extended axles, cut hangers or a purpose built hanger like most other pressfit drive systems with integrated bearings/spacers (17mm is what I use in the files as provided, but even this is adjustable).

[Linesflag]

How are the chain sprockets under load? I’ve never seen a 3dp chain setup, what are your experiences?

[ShutterShock]

Ooh great execution!

I had this idea a while back, but never ended up doing it. Thanks for providing!

Have you gotten a chance to put major miles on these yet? Do the pins stay in there with no issues?

[Brooklyn]

I don’t have a 3D printer but I would purchase some of those sprockets from you if you were interested in selling me any

[glyphiks]

These would be awesome for prototyping stuff or just low power budget boards.

Nice work dude, and thanks for sharing!

[Qwiksand]

I LOVE chain drive- so simple to set-up and modify…I’ve used it way more than belts over the years. For a wheel sprocket, I’ve never had a any type of plastic fail d/t load (a few PETG sprockets failed d/t curb impacts on some kneeboard set-ups I let my kids abuse). I use them on al kinds of litte light electric vehicle projects:

This little chain breaker/joiner is priceless- seamlessly makes chains of any size without screwing around with fiddly master links.

Chains allow the narrowest set-ups, this little set-up is on a stand-up scoot my youngest rides and is bulletproof- the sprocket on here is probably 6 or 7 years old and was printed in shitty old trimmer line before it was easy to get decent nylon for printing. In a well set-up chain drive, the metal driver/motor sprocket will wear out before the wheel sprocket.

I’ve played with printed motor/driver sprockets as well, when printed in nylon they’re actually usable (but not as reliable as steel, plus the steel motor sprockets are dirt cheap). The mangled one below was printed in PETG and was destroyed d/t chain misalignment rather than torque.

I did have a prototype integrated bearing sprocket failure when printed in PLA+ last summer, but the nylon versions held up fine (though this project was abandoned d/t the increased friction from the printed bearing races- just not worth it)

[Qwiksand]

Not a ton of miles on the pin design- been a rough winter here in western PA and I’m a fair-weather skater. The pins are press fit in with a clamp or vise like this:

They don’t come out on their own when the holes are sized properly. I’ll report back if that changes when the summer temperatures arrive.

As to the durability of printed sprockets in general…as long as the chainline is properly set-up, I’ve had several printed wheel sprockets out last wheels and motor/driver sprockets.

[soketsu]

have something similar but with steel sprocket from aliexpress

@Qwiksand

The mangled one below was printed in PETG and was destroyed d/t chain misalignment rather than torque.

Seems like advantage of having plastic sprockets that will serve as sacrificial parts in case of misalignment. Misaligned my steel sprocket twice. It snapped the motor shaft at first. The second time it snapped the chain.

This thread makes me wanna try printed sprockets.

[Linesflag]

wow looks promising! maybe I bust out my old chain stuff again.