"Mike" m.j.willis @rl.ac.uk wrote in message
...
In order to avoid the problems you have noted, find a thicker piece of
scrap
material. Make a sandwich with your aluminium panel as the filler. Clamp
together solidly as near to the hole position as possible. Drill through
the
whole sandwich. It is the only way I know to drill neat holes in really
thin
panels.

The extra sandwich material can be other aluminum OR hard wood,
dense fiber board, etc. Only trouble is that you can't see through to know
where you are drilling and must devise ways to line it up. A small pilot
hole in the top cover piece to line it up with a mark on the work.

The frozen water is a neat idea.

I have seen the uni-bit used on sheet metal ductwork & it makes clean holes,
but usually larger. Perhaps there are smaller ones.


HEY! Where do you get replacement thread-in tips for the old "automatic"
center punches, the spring loaded ones...slowly push until it pops ?
--
Steve N, K,9;d, c. i My email has no u's.