Chatter Problem

[joewino]

Following is the note I sent to support, but thought I would post it here also in case others may be having the same situation.

I'm having a problem with chatter when cutting HDU. Attached is a photo of the result of cutting a 4" circle in HDU. It was cut with a 1/8" end mill at 250" per minute (15,000 RPM). I've checked the table and it is level and square. Lately, the gantry will jerk just while moving it along the X axis, almost like it is in a bind of some kind. Also, yesterday, while moving the gantry the spindle just dropped down to the table top. There is some play in the spindle - I can grab the bit and move the spindle slightly, like something is loose...but I don't know if that is normal. At really slow feed speeds the chatter is not as bad, but it is still there. Any suggestions?


3822

[sawdust535]

I hope the 250" per minute is a typo or maybe you have a super charged bot. There should not be any play in the spindle when you grab and move it. That is more than likely the cause of the chatter.

[stevem]

Your feed rate is way too fast for a .125" bit.

[sawdust535]

sorry, I'm used to using inches per second. But at 4"/sec (250" per min) and with play in the spindle, this will most likely cause chatter.

[joewino]

Thanks for the responses.

Frank with support found the problem. In ArtCam Pro the tolerance had been set to .01 and it should have been .001. Made the change and everything is peachy-keen.

Cutting through HDU is like carving butter. Although the 250 inch/minute was for the test to create the chatter, I normally run it at between 150 and 250 all the time.

Since I lot of my work is 3D, it never gets a chance to run at full speed because it is constantly going up and down.

[knight_toolworks]

but it sounds like you need your machine while on see if you can move the x y and z axis if you can you need to find out why. pinions may be worn.

[joewino]

X,Y, and Z axis do not move. No wear on pinions. ShopBot (PRT alpha) only two years old.

[knight_toolworks]

I found worn pinions after 400 hours use.

[joewino]

No longer have the problem. Must not have been the pinions.