On Jan 1, 2:22 pm, Louis Ohland wrote:
I'm seeing a poor finish on a length of cold rolled steel (I dunno
what it is exactly). The tool is on center, RPMs are about 500, but
there are like little bits of swarf welded to the part. Sort of reminds
me of using a cheap ballpoint pen and the ink globs up and sticks to the
paper.

The cut itself is OK, but the surface finish looks poor.

I'm using an indexable insert with about a 1/32" nose (IIRC). This makes
me wonder if the insert is the correct grade, or maybe this result is
the best that I can get with this steel.

I'm entertaining thoughts of HSS, but the issue is who will grind it
when it needs to be resharpened? My dad has poor eyesight, so that's why
I went with carbide in the first place. That way I didn't have to be
standing at the lathe every second while he was working.

I can accept using brazed inserts or something similar, but grinding
relief angles is not an option.

If you want to stick with an indexable insert, use a Wiper insert. You
don't have to slow down the feed and the "smearing" action of a wiper
works fantastic on cold roll for a good finish. Tell me what size
insert you are using, ie..CNMG432 and if I have one I'll send it to
you for nothing. If I don't have a wiper and I do have the geometry
you are using, I'll at least send you the right grade and chipbreaker
for coldroll. I have boxes full of turning inserts lying around.
Generally on a 1/32 nose radius I never take less than .050 per side
depth of cut to finish cold roll. Less than that, all it does is
tear.