The Wobble

Ok, this is probably something user error, but I am gonna ask anyway. Running a pattern on my machine cutting some walnut for a clock. It gets maybe 2/3rds through the program and then I get a “wobble” that screws my piece up. It normally is occurring in the area of holding tabs, but not always. I am running a 1/4 endmill with 1mm Z-Steps-- Feed 15mm/s, and using a Harbor Freight spindle (yes I know I am a cheapskate). I noticed also that one of my lower bearings is not touching the Z-rail on the right side of the tool, but it does not appear to be loose. Do I need to decrease my Z step and drop the feed to see if the “wobble” / chatter goes away, or do you think it might be some other issue?



An 1/8" endmill is a better choice but. Are you using a finishing pass? Instead of cutting so fast try deeper and slower.

Have you tried foam milling first, this can answer a lot of questions?

As for the bearing they 100% should all be touching. Sounds like you might need a rebuild and less tension.


Good question! Can you change spindle RPM’s on your rig? That would be another thing to try. However, I’m not sure about the desirability of altering RPM’s as compared to the what you’re suggesting. Anyone know? How does one decide?

Just thought I would get the opinion of those much smarter than me. As the tool approaches the top left side of the cut it begins to chatter/wobble. You can see where it has done it a couple of times on the passes. I tore the head down and retightened everything just in case it was something working loose, but it still has just a little. It is always in that same area, changed from Walnut to Maple and same wobble in close to the same location. It occurs on the cut from right to left/ front to back (270ish degrees). -X/+Y Thoughts or ideas about what might be the cause? I posted a video on the Facebook page, but it was a little late for the forum.

What does it feel like when you manually move through that area with everything powered down? You might have a bend or rough spots in a tube…