In article ,
Wes wrote:

I just had something weird happen.

I was boring a .475 deep .624 dia hole in some 11L14 on my lathe.

Work was held in a 4 jaw chuck, boring tool was a boring bar for my
Bridgeport's offset
boring head, one of those brazed carbide bars.

I noticed I'd start taking a cut and after a certain distance in, I'd start
hearing
chatter. I removed the tool, double checked it was set it on centerline, and
even gave
the cutting edge a light honing to touch it up. Didn't help any. I also
looked for tool
rub as in insufficent relief.

Anyway, as I worked away, it became apparent my finishing cuts where not
tracking the
amount of infeed. I was using a telescoping gage and mic to measure.

Getting near where I thought I should be at the right diameter, I tried the
hex bushing
that I planned to press into the hole and it went in about 1/8". Now that is
weird. Why
only that far?

On each pass, I had stopped the lathe, and retracted the carriage w/o backing
off the
cross feed. That little scratch that can result isn't an issue since I'm
pressing
something in.

I decided to dismount the work and use the bushing to check the back side and
that was at
least 0.006" oversize.

The ways do not have detectable wear. This isn't a whooped lathe.

So what the heck happened? 11L14 generally cuts like butter and I've used a
lot of the
stuff.

I've turned a shorter piece from the same round w/o issues using the same
setup and I made
the same piece I was making tonight earlier.

For those that remember my recent post about screwing up a barrel plate by
tapping the
wrong sized holes, this was the replacement.

Was the heel of the boring tool skating on the side of the hole? It doesn't
take much. This has snuck up on me.

Joe Gwinn