If you didn't have pictures of it, I would say that pattern is impossible. I've never seen anything like that.
What end mill are you using?
Hi Guys,
I have this problem that I have not been able to figure out how to fix. Whenever I am cutting on Y axis regardless of end mill type or end mill size I use and regardless of tool holder I get this really bad chatter. Feeds and speeds don't matter much either. The only way I found to reduce it a bit is to go deeper with the cut and faster, but even then it does not cure it 100%. Something is wrong. At first I thought that perhaps X gib is loose but after adjusting that nothing has changed...
Same exact cut while moving X axis leaves very nice surface finish. See attached images. This was contoured in one pass. While cutting on Y, crazy chatter, cutting on X looks good. Same feeds and speeds same width of cut, same depth of cut. Y chatters, X does not.
Anyone have any suggestions?
Similar Threads:
Dennis
If you didn't have pictures of it, I would say that pattern is impossible. I've never seen anything like that.
What end mill are you using?
Jim Dawson
Sandy, Oregon, USA
As if the G-code already has a meander in it instead of a straight line...
That is not what I see when I see a chatter pattern. That looks like timing gears or something.
Does it sound bad when it is doing this?
Lee
End mill does not matter, I use Lakeshore Carbide and Destiny tool. Both do it. 1/4, 3/8 or 1/2 does not matter they all do it. Its got to be a problem with the machine.
Yes that is straight line movement on Y axis. Does not sound bad when it does it. Something is loose on machine I think I just don't know what it is.
Yesterday I was playing with it and I got it to mostly stop doing this by taking heavier cut at .04" (1mm) width of cut and at 31in/min (800mm/min) feed and then it shows just 1 or two faint lines like this at the end of the cut.
Dennis
Does the period of this pattern correlate with anything? Like, the rotation of the leadscrew?
Which direction are you cutting?
If it is chatter, you should hear it. Also changing the direction should help. Another thing that may help is to do a roughing and then a finish pass.
Lee
Are you climb cutting? Have you checked the lost motion in the Y axis?
If you have excessive lost motion it can cause strange kinds of chatter when climb cutting. See if a traditional cut does the same thing. And measure the lost motion in Y.
Little more info, each of those stripes appears to be about 3mm wide (little less than 1/8")...
Dennis
Right, I was referring to the direction of the cutter as clockwise or CCW around the part.
Lee
You should try going the opposite direction.
Lee
What is the pitch of the "Y" screw, it would seem you may have a problem with the screw, ie it may be bent or binding giving a slightly uneven feed. Dave
I wouldn't know how to generate that pattern if I wanted it. How the nice sharp edges on the stripes are generated with an end mill is beyond me.
Having said that, I would be taking a look at the X axis backlash. Maybe try running the cut again and lash up an indicator on the X axis to see how much it is moving. The other possibility that comes to mind is the quill or head is moving in the X axis plane.
Jim Dawson
Sandy, Oregon, USA
Normal chatter that I have seen on my small mill looks more of an angle and not a perfect pattern. I usually see evidence of tool flex when that has happened in the past. The pattern looked more like the pattern you miight see on a poor plasma cut.
Lee
Yes, my mistake, its climb cut.
I have just tried both climb and conventional cut, it results in same patter on side wall.
I have checked X axis backlash and adjusted gib. Its at 0.01mm. Y-axis backlash is at 0.01mm as well. Z-axis backlash is at 0.018mm. I think these are all within expected values.
Dennis