On Sat, 6 Feb 2010 05:54:14 +0000 (UTC), Andre Majorel
wrote:

Thanks for the hint, Ned. How do you know what press force is
needed for a given job ? Specifically, punching holes about
1 cm² in 1 mm steel or 3 mm aluminium.


Go to a site such as http://www.matweb.com/, look up the shear strength of
your material of choice noting the units psi..N/m^2 etc and converting if
required.

The force you need will be the area you're cutting through multiplied by the
shear strength, plus a bit for luck.


HTH

Mark Rand
RTFM