On Tue, 11 Sep 2007 19:33:45 -0700, "
wrote:

Hi Prometheus
Home shop square hole broaching is done quite easily.
Drill a hole the same size or slightly larger (like 1/32")
Grind the end of a same size tool bit square, and position and strike
the bid with a brass hammer, knock the bid back out with a brass rod,
and use a square file to remove the bur in the hole, don't try to
drive the bit all the way through, just repeat the short amount of
broaching, and filing the burr, if you use cutting oil it will help
with the broaching, but clean the oil out before filing.

Have fun and take care
Leo Van Der Loo

I believe you there- the bit I missed was using a brass hammer. I was
more giving a safety warning about wacking a toolbit with a regular
hammer.

The technique is a new one on me, but I'm sure I'll be trying it out
myself.