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Which plastic material for pedal bushes
jps - 20/3/19 at 12:21 PM

I need to make some tophat bushes for a pedal pivot - I'm thinking to buy a piece of rod from eBay and turn it down as appropriate.

I've seen what looks like the right stuff - but various options named as Delrin, Acetal, Nylon, PTFE, PVC, Acrylic, ABS, PMMA, Ertalon, PEEK, Polypropelene - just in the first page of eBay results!!!

Can anyone decipher for me what all these different options are (assuming some are the same thing under different names....)? And which one is right for a pedal bush (to be used with a crush tube)?

I currently have brass bushes - but assume a plastic material wil be cheaper?

[Edited on 20/3/19 by jps]

Mr Whippy - 20/3/19 at 12:56 PM

see link

linky

I'm assuming you have access to a lathe...

I turned quite a few things for work in nylon and it was super easy, even made a big square profile spring

[Edited on 20/3/19 by Mr Whippy]

40inches - 20/3/19 at 03:09 PM

Delrin machines like brass, I used to make knurled control knobs out of it, try knurling nylon
On the MK I used two ball bearings for the pedal pivots, smooth as a smooth thing

coyoteboy - 20/3/19 at 03:41 PM

Pick up some flanged igus X material bearings - cheap as chips and easy to press fit.

leon51274 - 20/3/19 at 04:08 PM

I always expansion issues with the bushes on my accelerator pedal when it gets warm, nothing more frightening than the pedal sticking!

mcerd1 - 20/3/19 at 05:00 PM

quote:
Originally posted by jps
I've seen what looks like the right stuff - but various options named as Delrin, Acetal, Nylon, PTFE, PVC, Acrylic, ABS, PMMA, Ertalon, PEEK, Polypropelene - just in the first page of eBay results!!!

That a pretty much a list of every plastic type you might use - with a huge range of different properties....



I'd be tempted by PTFE (or maybe even graphite filled PTFE) - PTFE is pretty hard wearing and effectively self lubricating
https://www.nogginend.com/product/PTFE-Round-Bar


but I'd also be tempted by a more old school bronze bush:
https://www.nogginend.com/product/Bronze-PB1-phosphor-Round-Bar



but for my throttle pedal I'm probably going to use roller bearings (possibly with some PTFE washers each side to help with twisting load)

coyoteboy - 20/3/19 at 05:30 PM

PTFE is pretty crappy for bearing material (it has creep issues and picks up grit really easily as it's pretty soft). Maybe filled it is a little better. Just because slippy != better bearing.

https://uk.rs-online.com/web/p/linear-plain-bearings/6671490/

Cheaper and faster than buying stock and machining yourself. But less exciting.

martin500 - 20/3/19 at 08:12 PM

Delrin and Acetal are the same thing and the best widely available material for your application, easy to machine and hard wearing.
As others have said PTFE creeps too much for this application
Some nylons are ok but they need to have fillers
As above, easier to buy Igus bushes.
Martin

[Edited on 20/3/19 by martin500]