HuFlungDung
Diamond
- Joined
- Jan 19, 2005
- Location
- Canada
1996 Haas VF3
I noticed a while ago that I get chatter in the cut when doing fairly heavy cutting (for a Haas). This chatter (tool screams) seems to be centered exactly on the 90° and 270° quadrant lines and spans +/- about 15 degrees each side of the quadrant line. Then the tool quiets down for the section of the path between the areas I described.
I was doing some clean circle operations today in C1018 plate, 1/2" thick. Part is held in vise. 1/2" 4 flute (evenly spaced) carbide endmill, full depth of cut, about .075 stepover per orbit, feedrate 35ipm, rpm 3500.
Varying the rpm and feedrate does not seem to be the cure all, although I suppose if I really slow way way down, it's going to quit sometime, but I'm not about to slow way way down
At the end of the clean circle op, I take a finish pass with about .0075" material to remove. I speed up the rpm to about 4500, cut the feed to about 20 ipm and the resultant hole is beautiful and round within a couple of tenths (as checked by chucking the part in the lathe and viewing the runout with a DTI).
A couple of months ago, I was roughing some aluminum plate, using Iscar insert endmills and in this setup, the plate was clamped directly to the table. So that takes the vise out of the equation. This was heavy plate but I noticed the same tendency to chatter. Because I was using a high speed milling strategy, there was considerable 'clean circle' type spiralling motion going on, and I noticed this same phenomena about when and where the tool was in the arc when the chatter seemed to peak. It was similar to what I described at the start that is happening today.
Anybody heard of such a thing? Could there be something 'loose' in the Z axis linear rails that would permit a certain amount of slack in the XZ plane but not in the YZ plane? I cannot visualize what kind of mechanical slack would account for such a strictly defined chatter area.
Normal X or Y linear cuts don't seem to cause any particular grief that I have picked up on with typical machine usage. Something about circular interpolation seems to be key. The fact that the machine makes a nice round hole (on a light cut) maybe is a distraction to me from learning the truth.
I noticed a while ago that I get chatter in the cut when doing fairly heavy cutting (for a Haas). This chatter (tool screams) seems to be centered exactly on the 90° and 270° quadrant lines and spans +/- about 15 degrees each side of the quadrant line. Then the tool quiets down for the section of the path between the areas I described.
I was doing some clean circle operations today in C1018 plate, 1/2" thick. Part is held in vise. 1/2" 4 flute (evenly spaced) carbide endmill, full depth of cut, about .075 stepover per orbit, feedrate 35ipm, rpm 3500.
Varying the rpm and feedrate does not seem to be the cure all, although I suppose if I really slow way way down, it's going to quit sometime, but I'm not about to slow way way down
At the end of the clean circle op, I take a finish pass with about .0075" material to remove. I speed up the rpm to about 4500, cut the feed to about 20 ipm and the resultant hole is beautiful and round within a couple of tenths (as checked by chucking the part in the lathe and viewing the runout with a DTI).
A couple of months ago, I was roughing some aluminum plate, using Iscar insert endmills and in this setup, the plate was clamped directly to the table. So that takes the vise out of the equation. This was heavy plate but I noticed the same tendency to chatter. Because I was using a high speed milling strategy, there was considerable 'clean circle' type spiralling motion going on, and I noticed this same phenomena about when and where the tool was in the arc when the chatter seemed to peak. It was similar to what I described at the start that is happening today.
Anybody heard of such a thing? Could there be something 'loose' in the Z axis linear rails that would permit a certain amount of slack in the XZ plane but not in the YZ plane? I cannot visualize what kind of mechanical slack would account for such a strictly defined chatter area.
Normal X or Y linear cuts don't seem to cause any particular grief that I have picked up on with typical machine usage. Something about circular interpolation seems to be key. The fact that the machine makes a nice round hole (on a light cut) maybe is a distraction to me from learning the truth.