On 8/30/2012 7:59 PM, Tim Wescott wrote:
I may have asked this before, but I'm slow:

I have some 304 sheet. I use it to make control-line model airplane
handles. Each handle needs to have about 20 1/16" or .050" holes drilled
in it, in a pair of tidy lines.

This stuff breaks my regular old HSS drill bits, and my drill hand-
sharpening mojo is pretty spotty at 1/16".

I'm using them in a drill press. The whole process feels weird -- it
feels like there's a skin on the metal which prevents the drill from
starting to cut unless I feed it fairly hard, but once broken through
doesn't cause much problem. Most of the time that I break a drill bit
it's because I'm feeding it "just a bit harder", then SPING -- I've
broken another bit.

Is there a better drill bit to use, or have I just doomed myself to
trouble? Is there a better flavor of _stainless_ to use? I understand
that 304 is difficult to work with, but it's what McMaster had in the
thickness I wanted; having experienced its joys, however, I'm ready to
consider something else.

I think my next step is to get a dozen 1/16" drill bits, but if there's
some magic material that'll help here, I'm listening.

304 SS is junk stainless, but cheap. The reason it's so hard to cut is
an absence of sulphur in the alloy for lubrication. You have to get the
speed & feed just right to cut it, and you still get short tool life. A
few more pennies spent on a better alloy will save a lot in tooling.

Or have the parts cut on a LASER, we cut 304 all day long and the LASERs
don't wear out!

David