View Full Version : Delrin AF question

A.K. Boomer
07-28-2006, 12:58 AM
My experimental cranks logged on over 200 trouble free miles and now im freeing up some of the internals with some Delrin AF bushings instead of steel on steel, got the bushings installed and bored and am ready to make up the drive pins that rotate through the bushes, question, does it matter what kind of steel pins i use with this plastic? I was just going to go with a 303 and really good finish, this delrin is supposed to be self lubricating because it has teflon in it but the bushes will also be living in mobile one synthetic gear lube,,, thanks.

07-28-2006, 01:18 AM
It shouldn't matter. Btw, I just priced some of that. 2 1/4" round stock is $75 per foot. Don't waste it.

07-28-2006, 01:30 AM
Enco's sale flyer shows 2-1/4" black or white acetal rod at from $76 to $82 per 4' length. I've bought the same stuff at a surplus/salvage yard for a lot less in the past, but haven't turned up any more of it during the last several visits to the place. It sure does make nice bushings for use on the lathe.

07-28-2006, 01:41 AM
That isn't the same as Delrin AF. I can get 2 1/4" acetal here for $17 per foot.

A.K. Boomer
07-28-2006, 08:58 AM
Lucky the parts im working on are small -- 3/8" and it only took a half foot so i got to use my friends scrap :eek:

07-28-2006, 12:12 PM
Pin material shouldn't matter much running delrin in an oil bath. Heat expansion of the delrin will be different than that of the 303 so take it into account when you fit it up if you haven't already. Have you thought about some internal oil grooves - it might minimize metal to metal contact and allow a slightly tighter fit-up.

Can't recall if the molecular structure of the synthetic is smaller than dyno-lube. Might be someting to look up - could allow some tighter tolerances. Too tight and you burn up, too loose and you self destruct if you expect very high RPM on a less than perfectly balanced load. YMMV

A.K. Boomer
07-28-2006, 10:29 PM
good advice, high load, very low rpm, no heat to speak of,,, thought about cutting in some oil retention groves but really dont think it ness. and am pushing it on bushing surface area and want to keep all i can, only thing iv heard about synthetics is the structure is indeed smaller and much more uniform as compaired to mineral, im going this route because i used some delrin AF in a few other places on this project and i cant believe how durable it is,,, its outlasting the bronze bushing in other places 3 to 1...