In article .com,
himog wrote:
Grant Erwin:
Many many boring bars have square holes, one at 90° and one at 45°.-


None of the boring bars I have seen have holes in them for holding
cutters.

I think that you are confusing two things with the same name.

There are boring bars made to mount in boring/facing heads, and
I have never seen one of those with sockets for HSS tool bit. (Square
holes.)

However, boring bars made for *lathes* often are made of plain
steel, with square holes and setscrews as described for holding HSS
lathe bits to do the actual work. Sometimes, the bore is hollow and
filled with lead shot to reduce chatter.

These lathe boring bars typically have different angles at the
two ends. The end with the bit held at 90 degrees is for plain through
boring. The end with the bit held at 45 degrees is intended to be used
for boring to the bottom of a blind hole and then to face off the bottom
of the bore. Those cannot be used in a boring head, and are not
intended for such usage.

Granted, these days, there are nice carbide insert boring bars,
sometimes made with solid carbide shanks, and these don't use HSS lathe
toolbits.

My most recent use of such a boring bar was for some inside Acme
threading in a size a bit too large for my insert tooling. Even with
nice insert tooling, the old tools are quite useful at times.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---