"Robin S." wrote in message
...

"Craig" wrote in message
ups.com...
What would be the best way to cut a round bottom groove (need a few
diff. sizes-1" 11/4" and 11/2") in a piece of steel about 8-9" in dia.?
I want to make dies for a tubing bender. Would a radius attachment work
for something like this? Where could I find one?

Do you want to buy one, or make it? If you want to buy one, you may want
to talk to the lathe manufacturer. You might be able to buy after-market
ones as well.

If you want to make it, you can look for examples and perhaps plans on
google. Search for "radius cutting attachment lathe" or some such. Here's
an example I found: http://www.jerry-howell.com/Radius.html

You could also use some math and calculate some depths for a grooving tool
(say, 1/4" wide if you have a heavy lathe, smaller if necessary) to rough
out the groove. Then file finish. Sounds like a lot of work, but
building/buying a radius attachment for your lathe could cost serious
hours/dollars.

FWIW, I built the one referenced above from Jerry Howell's plans - a picture
of it is buried in one of Jerry's galleries. I modified it to fit a
Craftsman 12x36 lathe and it worked very well for the only job done with
it - the ball for the radius attachment handle! I never tried it with an
internal radius but expect it would well for that, too. I've since upgraded
lathes to a Clausing 5900-series and will eventually get around to modifying
the attachment base for the Clausing lathe.