On Mar 14, 1:05*pm, Jon Elson wrote:
Spehro Pefhany wrote:

Looking at using some relatively small screws tapped into (probably)
6061 aluminum. Through holes, maybe 0.08" of material. Is it insanity
to think about using a cordless hand drill and run them right through
without backing off (assuming a good quality coated tap and aluminum
cutting fluid)?

I tapped quite a bit of 2-56 in 6061 using Alum-Tap fluid on a CNC
with rigid tapping. *I used some $8 spiral-point taps to push the chips
ahead. *The CNC guaranteed alignment straight over the hole.

There is a limit to how deep the hole can be for any particular tap
size, or the chips start to pack up and that's when you break the taps.
The tap manufacturer should have data on that.

The smaller the tap, the more critical the alignment parallel to the
hole becomes.

Jon

A roll tap wouldn't produce any chips.