pic: No Pulley? No Problem!



One of 1885’s design gems this season. It held up through DCMP 19 matches with no signs of wear. We didn’t want to 3D print a pulley since we didn’t want the pulley shattering during rough play.

Roller is 0.5" ID polyurethane on a 0.5" OD aluminum tube and sits on the outer-most part of our dual-wheel active gear intake… Motor/gearbox setup is a 775Pro through a 5:1 VP. Roller is supported via R6 bearings in 1x1 thick-wall box. Roller isn’t precision-aligned parallel to the VP gearbox, but with this setup it doesn’t have to be. Required tension is “about precise” center-to-center for typical 5mm HTD.

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No load, no problem?

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Always nice to see what teams can get away with in practice.

Always remember - FIRST isn’t industry :wink:

I like it

Why does your flat belt have weird little ridges in it? :stuck_out_tongue:

I saw a team in Israel that did something similar for their ball intake, but they flipped the belts onto the flat side and used them as flat belts with crowns on the roller to keep them in place. The belt teeth increased traction and helped grip the balls.

For the record, 3D printed pulleys work pretty good.

Render:
https://lh6.googleusercontent.com/BiSCHapYWPY5Qn1b6hkpVffFPSGRQ-3Y_4UcbnyORq0wllSheuZSR8qO7mK9duxopKKc8txPtCSzrojR6Wky8Hgl19av9U1Uh2tqvXH74yR-NPpRs09TnFpP-gaELuqwbuEWQBwQ

Video:
https://drive.google.com/open?id=0B5nD41bQM7QuckVDcWlfaTFUcWM

But yes, you probably don’t want them exposed and taking hits from other robots.

I can confirm that printed pulleys do hold up. We printed HTD5 pulleys for the intake. 3/8 hex drive shaft. These are pla printed very hot (230c). No layer adhesion problems. Found that Inland (Esun) PLA is stronger than many on the market. We also printed idler pulleys on the CVT swerve module. Pla did not hold up. They were reprinted in PETG and the PETG has held up. PETG is becoming the go to filament for most parts on the robot. We also print them very hot for layer adhesion(270C).

The pulley would have to be able to handle being among the first things to hit during a 10ft/s+ collision. We didn’t want to risk it, since it would effectively render the intake worse than its non-upgraded form (without the horizontal roller).

I’ll have to look into whether our printers can print PETG - our current (known) options are PLA and ABS/Nylon.

However, now you have my curiosity - what is this CVT swerve module you speak of?

Warning- PETG is a pain to print. If you can print nylon then PETG is an option.
CVT swerve
http://team1640.com/wiki/images/2/24/DB13_170212-17.jpg

This is honestly pretty dope.

K.I.S.S. at it’s best!

I am sorry that our team members will not be able to see this up close. Best of luck in St. Louis!

I’d love to see a booklet on the “dirty” stuff you can get away with in FRC that aren’t technically “right”, but makes things way easier. There are some better known ones like adding 2-3 thou in center-to-center distance in gears to get away with a bit sloppier tolerance (and probably other reasons) and adding 12 though to #35 chain to get out of ever needing to tension. But I’m sure there are way more things teams have done to make things cheaper/easier/faster that aren’t as well known.

Or just y’know 3D print your swerve modules: https://www.chiefdelphi.com/media/photos/44578

Works great for electric bikes as well

EDIT: Broken image link.

Do you guys plan on doing any white papers or documents explaining the design and the thought process behind this? And if not, do mind if I pick your brains via PM? I’ve been working on a CVT design for FRC, but I haven’t been able to get to a simple enough design to justify the benefits yet.

Sorry for going off topic of the thread. I like the idea of just letting the belt’s teeth grip into the polyurethane. What’s the OD of the polyurethane?