nick baker
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| posted on 22/2/05 at 09:02 AM |
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shouldn't be aproblems as it shouldn't be allowed to get hot...
If your plakky get hot when you machine it, you're doing something wrong!! 
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Alan B
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| posted on 22/2/05 at 01:06 PM |
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quote:
Originally posted by Rorty
I use PTFE impregnated acetal for bedal and gear linkage pivots. Best of both worlds with moisture absorbtion less than 0.2%. Nylon will swell far
more in a damp environment, which can result in a tight bush.
Is Delrin (acetal) available in the UK? I thought it was a US brand.
Rorty I believe that Delrin is a US brand name, although acetal branded some other way should be readily available everywhere.
I agree BTW, Delrin is great stuff.
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liam.mccaffrey
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| posted on 22/2/05 at 05:00 PM |
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my local machining guys makes stuff from "delrin" all the time.
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timmy
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| posted on 23/2/05 at 01:55 AM |
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Just to stick in my 2c... (I used to work in a plastics engineering crowd):
Nylon is a great material for bushings in general. Very tough and easy to machine. Moisture absorption is it's downfall but only really if
it's extremely humid or is immersed in water. You can get oil-filled nylon also (oilon, Ertalon LFX) that is even better but a bit more
pricey.
PTFE/Teflon is also a great bushing material but it's quite soft, expensive and wears away quickly.
UHMWPE (Ultra-high Molecular Weight Polyethylene) is sometimes mistaken for teflon because it's really slippery. It's also good for bushes
but it's also soft and difficult to machine if you don't have the right tool (ooh er) - it can get really stringy when turning. But the
wear resistance is shedloads better than telfon and is heaps cheaper.
Some of the other engineering plastics - Acetal (Ertacetal, Delrin) and PETP (Ertalyte) would also be good for pedal bushes. A bit brittle but
excellent for machining and very precise. Also there is bugger-all moisture absorption.
Hope this helps....
Tim
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Rorty
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| posted on 23/2/05 at 02:05 AM |
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Timmy, you didn't happen to work for Dotmar PBE by any chance?
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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timmy
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| posted on 23/2/05 at 03:24 AM |
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Nope - but I used to deal with them very closely when I was in that game.
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bigandy
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| posted on 23/2/05 at 08:55 AM |
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Thanks for all the info chaps, it is much appreciated!
I've got a few lengths of acetal (Delrin apparently!) on order, so I'll see how i go with machining that on my little lathe!
Cheers
Andy
Dammit! Too many decisions....
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Terrapin_racing
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| posted on 24/2/05 at 10:53 AM |
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Done this type of work many times. Without doubt the best material to use is green self lube nyloil (RS components sell this relatively inexpensively
in 1m lengths)
Typical coefficient half that of other lubricated nylons
High resistance to water consumption
Excellent hardness, durability and creep resistance qualities
Free cutting properties enable tight machining tolerances
For all bearing, bush, gear, roller and wheel applications
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