Drilling VERY ACCURATE holes in delrin

[kbspeed]

Just started in a new shop and trying to win some at a boy points. Holes are .056" dia., 1" deep thru holes.

Now the difficult part, electrical connecting pins are being pressed into these holes. For the best fit without bending the pins they are trying to make the holes .0005 undersized. Having a hard time finding drills that will drill the same size hole consistently. I guess they have tried reamers and have had the same problems.

Any help is appreciated.

[John Welden]

I don't see why you can't ream them. Works just fine for me. If the hole comes out undersized, just use a bigger reamer. If you ream the hole on size, you should get a nice press fit for the pin.

[beege]

Try half-round drills. Not too fast, or they'll melt instead of cut.

[monte55]

I don't know how how many pins per piece you're dealing with or the shape.
Get the hole slightly under sized, cool the pins and heat the receptacle and push them in.

[jalessi]

http://www.ohiodrill.com/ShowSub.aspx?dept_id=13

[Geof]

Working to 0.0005" in Delrin is a lost cause.

Is 0.056 a standard number drill size?

If the answer is yes I would try going one size under, drill the hole with lots of coolant and then with a brand new 0.056" drill and lots of coolant I would go in and out very fast; sort of using the second drill as a reamer.

In and out very fast is something you will need to determine by experiment.

I have done this type of thing with plastics and I suspect that what happens is the second drill leaves ridges that grip the pin when it is pushed in...really tiny ridges.