help for countersinking Teflon Sheet

[Astroman]

Hi all,

I have a sheet of 1/8" thick teflon sheet and wondered what tools others have used to countersink the material. I tried using a drill, just slightly larger than the screw head, but it kept grabbing at the teflon and was difficult to get right. Is there a tool I could use which will help?

[leon]

Yes there is, just go to Bunnings or similar place and ask for a counter sink bit, they will counter sink any size drilled hole, pretty cheap as well.

Leon

[Astroman]

So these shouldn't grab the teflon like a drill bit? Thats my main concern, I don't have a great deal of the teflon so don't want to waste it.

[Blue Skies]

I usually use a countersink bit, no problems. Drill a guide hole first and off you go.

[leon]

No definitely wont grab, i have been using these for years on any material, if in doubt try it on a bit of scrap first, you will be pleasantly surprised.

Leon

[Astroman]

Thanks, I think I used to have one but cannot locate it now, so will go get another.

Thanks Leon and Jacquie

[AndyK]

Normal drill bits can be a bit problematic on some plastics. A lot depends on the angle the cutting edges have been ground to ... which are different with plastic drilling compared to for metal drilling. Also drill speed can be a factor.
You might want to consider using one of those conical grinding stones which can be used in drill chucks. Just take it easy to avoid overheating and you should be OK.

[jenchris]

Clearance and rake are rotated a lot on soft material drills - so that the rake is almost zero and the clearance is almost zero - that way the drill doesn't dig and the cut doesn't drive the drill in. This can be simulated with a stone - take the stone to a drill so that it's a right angles to the face and give it a few stokes along the line of the drill.
This will take the rake off at the tip and then stone the clearance off for a few strokes - that's the angle of the end of the drill that leaves the cutting edge clear of the shank.
Then use a high speed and no force to drill

[Astroman]

excellent ideas all round, Andy, Jennifer, thanks a heap, my son needs to goto Bunnings so I might have to tag along with him :D I'll keep the drill idea at the back of my mind so if I ever misplace the countersink bit again...

[DavidU]

These countersink bit's are the only way to go with Teflon.
http://www.clearpc.ca/catalog/images/13countersink.jpg