Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the Delrin
would do the trick, but it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it
& be done. I've seen spectacular failures with regular Locktite
getting near some plastics. They do make a special version for
plastic parts, but McMaster wants almost $20 for a bottle that will
spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I bore
all the way though and can adjust the locking screw from the far
side. I can try to thread the holes _just_ deep enough to hold the
screws at the right height, but if I overshoot, I'm stuck with Plan
A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according to
the datasheet. The datasheet (or app notes) tells how aggressive one
should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the nylon
set screws. It might take a little experimenting, but I think that would
work OK.

Thanks!

Doug White