DIYbanter - Curious pattern on lathe cut

On Feb 27, 9:13*pm, Bob Engelhardt wrote:
http://home.comcast.net/~bobengelhar...pledCut.jpg(90 kB)

I was trying out some bits that I had just ground & fooling around with
the independent feed on my lathe when I got this strange ripple pattern.
The ripple peaks are about .030 apart, but the feed was only .002. *And
the ripples are rings, not a helix. *It's mystery metal.

I'm speculating that there is a rub-then-cut kind of oscillation going
on. *That is, the .002 feed is not enough to get a bite on the steel, so
it rubs a while, without cutting until enough advance occurs then it
bites/cuts until the pressure is relieved and goes back to rubbing
again. *Does that sound right (it's not real clear how that would give a
ripple pattern)?

If so, is there a way to avoid it? *I thought that I had the bit pretty
sharp (it was just a plain RH roughing bit). *Could it be lack of
rigidity in the lathe?

Thanks,
Bob

Maybe it's from the apron feed gears?