J Gold wrote:

Hi Jeff,

Does it really make a square hole with sharp corners or does it make a
square hole with slightly rounded corners like the one shown in the
figure on http://mathworld.wolfram.com/ReuleauxTriangle.html ?

That depends on your definitions of "sharp" and "slightly rounded,
Jerry. :-)

I did locate a Brit manfacturer of them:

http://tinyurl.com/8wh7h

And that page states:

**************************

QUALITY

Square holes are produced with corner radii. The tools could be made to
make the corners square but would have too short a life to justify their
use. Hexagon, octagon and other polygon holes have sharp corners. A
short stubby push broach can be used to clean out the square corners,
but would not normally be required.

*************************

So I guess they're not really "sharp", but probably good enough to be OK
for accepting things like carriage bolts or the kind of square tubing
used for "wrought iron" stair rails.

Jeff


--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."