----- Original Message -----
From: "David Billington"
Newsgroups: rec.crafts.metalworking
Sent: Tuesday, October 11, 2016 2:38 PM
Subject: Square holes...

That's called a rotary broach, and last time I looked they were pretty
pricey.



I think actually a different beast as a rotary broach has the same form as
the shape it cuts whereas a square hole drill has 3 cutting edges as shown
here http://www.integerspin.co.uk/polygon.htm and operates in a different
manner to a typical rotary broach.

Ok, maybe, but Polygon calls them rotary broaches.
https://www.youtube.com/watch?v=smTdkevMMTc