Feed and Speed - Long Skinny Part

I'm a rookie, trying feeds and speeds for roughing. The tapered aluminum rod cuts with the numbers below, but I'm wondering if anything looks out of the ordinary to an experienced machinist. The sfm that I'm running is really low, but I don't know if that's normal for a skinny part. Should I be trying for 800-1000 rpm to get over a resonance, or just be happy here? Is this a deep or shallow cut for a skinny part?

2024 aluminum
30" between supports
1.5" stock left raw at one end
1.0" diameter at small end

MCMNN holder with a Korloy 432 made for aluminum
Flooded

.035 depth of cut
.017 feed (.012 to .020 made little change)

600 rpm chattered aggressively more than 6" from end support (230 sfm)
400 rpm brought ringing or chatter down to a dull level (160 sfm)

Have you tried playing with the spindle override while in the cut? +/-20% back and forth can quiet things down a lot. Haas has this built in as a feature on their newer machines.

I would suggest using something like a DCMT with as sharp as a radius as practical to limit tool pressure.

Also not sure if this is manual or not but some guys will hold a stick or other object against the part in the cut to break up the resonance but do with that what you will.

Hazzert said:

Also not sure if this is manual or not but some guys will hold a stick or other object against the part in the cut to break up the resonance but do with that what you will.

Click to expand...

It's a 1999 Milltronics ML20 cnc. I think it predates the oscillating rpm features. The damper stick idea is interesting, but I'm planning to do other things while these run.