Drilling stainless stack

[Biz]

What is the best way to drill holes in stainless stack? A standard high speed drill bit walks or bends when trying to drill the stainless, even when using in a drill press, worried that bit will snap if I use too much pressure. Dimpling doesn't seem to help much. I have a cover to install. 7" SS stack, hole needs to be about 3/16" diameter. Thanks.

Dave

[johnallin]

I use a step drill bit.
18702

[buckeye gold]

I used self tapping screws. It helps to drill a small pilot hole first, it can be pretty small and that should make it easier with a variable speed drill go slow.

[Russell Lampron]

I use molybdenum drill bits. Start out with the smallest one and work your way up to 3/16". I drill the pilot hole then go up two sizes at a time until I get to the size that I want. Use cutting oil too, it makes a big difference.

[maple flats]

And I use Cobalt bits, not cobalt coated, all Cobalt bits. They are intended for drilling hard and difficult metals. I start small then drill larger. For 3/16 I would start with a 1/8" or maybe a 3/32 then the 3/16. Smaller sizes are quite likely to break. If in doubt, duct tape a piece of wood over the spot, then drill thru the wood.

[upsmapleman]

If you want to drill stainless start with a sharp bit, slow speed (i mean really slow) lots of pressure and of coarse cutting oil is a big plus. If you go to fast you will take the edge right off a bit and no matter how hard you try you won't get any where.

[Super Sapper]

If you want to drill stainless start with a sharp bit, slow speed (i mean really slow) lots of pressure and of coarse cutting oil is a big plus. If you go to fast you will take the edge right off a bit and no matter how hard you try you won't get any where.

This and use some wood for backing on thin stainless.

[Kbrooks80]

What is the best way to drill holes in stainless stack? A standard high speed drill bit walks or bends when trying to drill the stainless, even when using in a drill press, worried that bit will snap if I use too much pressure. Dimpling doesn't seem to help much. I have a cover to install. 7" SS stack, hole needs to be about 3/16" diameter. Thanks.

Dave
Lots of pressure, sharp bit, and slow RPM's

[Biz]

Thanks for all the replies, I will try this soon!

[crzypete]

Cobalt bit, 135º tip with split point, ideally in a short length- screw machine length or stub length would be names given to these bits. You will be amazed at the difference in performance over a standard 118º bit.

Peter