Thread: Press fitted nylon bushes

Plastics will creep under load, so while it may start off as an interference fit it may relax over time. From memory, I don't think that filled plastics are as bad for this.
Ideally I'd talk to an engineering plastics vendor (for example Dotmar) about what they would recommend as there could be something that is just right for this sort of application.

Michael

Bob,
Can it be a flanged bush? pushed in from the top. nylon bushes are every where these days in steering column assembleys, both solid and split.
Ted

Hello Bob,

IME nylon is not a good material for bushings. For a start it is not good to machine because it can be difficult to get a clean and precise cut. Second, it changes dimension considerably with change in moisture content, so can start out tight in the housing then later loosen when things dry out in a long dry spell. Or you can have a nice running fit that later tightens up in in humid weather. I recently experienced this with a nylon bushing that was fine when I disassembled the equipment. After a few months I could not get it together again because the shaft would not go through - Sydney humidity was the problem I think.

Delrin is much better as a stable engineering plastic that is easy to machine and readily available. Just put a dab of grease on it and it will be good for years.

Regards,
Bill

one you desided on the material. id use a bit of locktight.
and getting the id of bush to column fit right might be
your only problem. You could make the id slightly larger
than needed to allow for any shrinkage due to the press fit.
If you have the right size sharp reamer you could run
it down the bush after fitting it
aaron