Haas Lathe TL-25B with live tools

[LONERO]

HAAS LATHE:
TL-25B with live tools. A current machine process of ours - cutting scallops on an o.d. - we can cut at 20"/min 3200rpm - climb cutting - N-mill is a 3/8 dia. YG1-V7- with no problem on a vertical mill. When we try to make the same cut on the TL-25 at that speed we get chatter. In order to achieve the same quality of cut we need to slow down to 5"/min at 1250 rpm. Now the coupling for the live tools has a bunch of slop (maybe .06 backlash) could this be the reason? If so does anybody have a possible fix? -

[Donkey Hotey]

I don't know specifics about the TL25 but the C axis on the lathes is basically in the spindle motor, isn't it? I'd imagine that the spindle simply doesn't have enough positioning power to hold position against an endmill, climb cutting, at that feedrate. That's my guess.

[CNCRim]

the only thing I can thinking of is not rigid enought = chatter & unaccurate.

[Edster]

The c axis on a haas is a big gear mounted to the spindle. A servomotor with a small gear is mounted on a plate that pivots which makes the gears mesh when the c is engaged. I think they have a hydraulic brake too, but I'm not sure. My okuma has two settings for the brake. One is a light clamp used when milling with the c axis the other is a heavy clamp used for keyway cutting where the c isn't rotated.