On 7/30/2019 4:49 PM, Jim Wilkins wrote:
"Bob La Londe" wrote in message
...
"Bob La Londe" wrote in message ...

I can just grab a piece of tool steel and go stand in front of the
grinder for a while, but I was wondering if there is a simple
elegant,
not over priced tool to do the job. Ring groove will likely be
1.1"
give or take.

**********
Seems the old school round boring bar with square broach and set
screw might be the best tool for this job. Atleast I can pregrind
two or three HSS bits the same for this if I wind up doing a bunch
of them.

Now about face trepanning a recess that butts up against a shank
diameter. For now I have been using a hand ground brazed carbide
inside threading tool. It no longer looks like a theading tool and
has relief on one side for the smallest diameter of the recessed
area.

I use a worn surface grinder I bought for $100 to grind lathe bits to
close angular and dimensional tolerance, after roughing them with an
angle grinder and then a bench grinder.

If your toolpost will swivel to it, 45 degrees is a good tool bit
angle for custom inside corner tools, ground into the end of the bit.
For that tool grind the end slightly less than 45 degrees for side
relief and grind a vee notch to form the outer cutting edge, then
relieve for circular clearance. I have a Multifix that indexes in 9
degree steps.



The QCTP on the PM1440 free spins so I can set it at any angle. I can
see how turning it would work with the 45 degree bar. The lathe bit
would have to stick out a little more, but it would work.

I've been playing with the idea of CNC roughing the part on the mill,
and then just throwing it in the lathe to finish. Maybe leave the OD 10
thou over, and the ID 10 thou under on the two dimensions that need to
be pretty concentric and just finish those on the lathe.