I have to drill holes in 1/8" thick stainless plates and mount 1/4" screws. I'll most likely use screws that have a 45 degree taper. Anyone konw how to drill out the stainless so that the screw heads sit flush on the holes? Is there a special bit that I can use to do this?? Any help would be greatly appreciated.

It is called a countersink, if you are going 45* into 1/8 inch material, you will probably have to countersink the base material sligthly in order to get the head to sit totally flush.

http://www.mcmaster.com/

page 2313

or do a search for "countersink"

Most screw heads have an 82 degree taper, not a 90 (45 per side).

Most general purpose drill bits are 118 degrees, and some of the newer split point sets are 135 degrees.

While you CAN use a larger 118 degree bit to sort of countersink the hole, it will not be "correct".

A single-flute TiN coated 82 degree countersink can be bought at a local metalworking supply house for around $10 (I've seen complete sets for under $20 for import HSS).

Mix up some some water in a used dish soap bottle and squirt it on the bit while cutting (do this for the drill bit and the countersink). The soap residue in the bottle will be about right for a light soap water mix - the soap helps the water stay on the bit instead of running off immediately.

Cool bits last forever - it is the heat that gets them. Stainless steel is the worst metal you will encounter to work with as far as heat on your bits. Use lots of water on it.

Metric counter sinks are 90 degree...we use them in our machines that we build.....Fred

And use low speed with moderate pressure. Almost to the point that you can count the revolutions.
Faster speeds does not mean it will drill faster. Just burn up faster.

fred
Metric! I aint converting to no metric system till they bury me 2 meters underground.
Gary

They sell those at Home Depot... I bought mine there for a couple bucks. It lasted the 14 holes I had to do.

Kaniikstr,
Were you drilling into stainless with this bit?

I originaly used it alluminum, but I used it to make 3 holes in S.S. I wouldn't by it if I had to make 10+ holes, but for the 2 that your talking about. You should be fine...