Originally Posted by
johnnydoejr
I should mention that this machine is used by multiple individuals, I'm just the one trying to run down a solution. We all see the same symptoms and it's been going on since we received the machine (i.e. it didn't develop out of a machine that was running smoothly). Since none of us are professional machinists we initially assumed that this problem was user error (in feeds/speeds, etc.) and so we weren't actively troubleshooting from the perspective of a potential problem with the machine itself. Because of this, we've had the machine for a quite a while and in that time have tried every combination of variables we can think of to isolate the cause. Stub tooling, set screw holders, different diameters, tool manufacturers, coatings, tool geometry, etc. It's all the same result.
We have a power draw bar but I will do some cuts after manually tightening the collet to eliminate it as a source. Spindle preload was next on my list. During the chatter the surface finish suffers everywhere, but the bottom of the cut (at the face of the end mill) is especially bad. Maybe that's an indication of axial movement? I just have no reference for whether that's typical of chatter that isn't attributable to axial movement also, because again, I'm not an experienced machinist.
Thanks for the help. Open to other suggestions of things to check as well.