On 04/06/16 13:21, Jon Anderson wrote:
On 4/06/2016 9:44 PM, Jim Wilkins wrote:

Have you considered Greenlee punches?

Good tools, I have a few. But would only work in a few instances.

I've used one of these at a later job.
http://www.roperwhitney.com/bench-deep-throat.html

This is more what I want for the shop, but not having much luck finding
something equivalent down here. Have only found a couple models so
far, not up to the Roper Whitney level.

I have the XX model hand punch, nice unit.

I was just trying to figure out what aspect of drill geometry
contributed to lobing and reduce it if I could, just because.
Our work is pretty crude by the standards of most here. Need a hole
for a 10mm bolt, just drill 10.5 or 11mm, nobody worries about nice
round holes... Hole making is 95% 304SS in material thicknesses from 1
to 40mm. Holes in thin material are only part of it. Appreciate the
time to respond and offer the suggestions.

Jon

Jon,

As your problem is the hole starting out trilobal I would expect it is a
2 flute drill. polygon drills have one less cutting edge than the shape
they cut so a square hole drill has 3 cutting edges, see
http://www.integerspin.co.uk/polygon.htm

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus