What I've learned about MPCNC maintenance

I’ve not seen this addressed in the forums, so thought I’d mention a few things I’ve discovered that require some periodic attention. I found these when I started to see jerky movement on curves doing routed boxes.

First, clean the bearings! I’ve found that cutting even a short time without vacuum dust collection (and sometimes with it) that a “cruft” builds up on the roller bearings on both the gantry and the servo carriages. This leads to a bumpy movement and results in some jerky movement when milling, especially on curves or diagonals. I’ve tried both mechanical and chemical (lacquer thinner, mineral spirits) cleaning, and found the mechanical cleanup to be much superior. I use an Exacto knife blade held perpendicular to the roller surface and roll the part back and forth to knock off all the cruft. Then I use steel wool on the rails to get the junk off of them.

Cutting pine is the worst for crufting up the bearings. Oak and maple are next worst. All woods seem to have this effect, though.

Second, check the tension on the bearings. Too tight and it binds and jerks on the cuts. Too loose and you lose precision, but overall looser seems to work better than tighter. I’ve found that they tend to loosen after a some “burn in” of a new design, but thereafter don’t require much attention.

Third, make sure the belts retain the proper tension. If you follow the assembly instructions and let the cable ties sit overnight before final tightening, there’s a good chance you won’t have to adjust them much, but I’ve ended up with 1 or 2 getting a bit too floppy after some heavy use.

Fourth, lubricate the lead screw and clear the bearings on the Z axis. This is a prime location for dust. If the Z axis is binding when rolled up near the servo, I found in my case that it was an issue of alignment in the split coupler. I found that this slipped once and found that if I filed a flat on the lead screw where the coupler attached, then it would not slip at all.

My machine is 24" X 40" built with stainless steel tubing.

Would love to add to this list if I’ve missed anything to keep the quality up.


Nice list, thanks!