Probotix CNCs, Square and Plumb
Don't take this the wrong way.... I love the CNCs made by Probotix. We have a Meteor where I work though which has always been reliable... except when precision of detail alignment or dimension has been a critical factor.
I've lately been perplexed more than usual on why joinery cuts on my vertical clamping jig have been misaligned. Over the Thanksgiving break (9 days when no students were on campus) I decided to get to the bottom of the mystery.
With squares and precision measuring rules I went at this old Meteor. My findings surprised me, but do explain why so often over the last several years I've been dissatisfied by the results of a cut.
1. The Z axis assembly was not square to the frame or X/Y travel plane. Tilted back roughly 2 degrees.
2. The gantry wasn't parallel to the front/back frame members. Approx. 1/16" back on the right side compared to the left side.
The gantry alignment is set when homing. Limit switches on the right and left hit a triangular bracket screwed to the bottom of the side frame members. In this meteor the bracket on the right was 1/16" farther back than the one on the left. A relatively easy fix, but also should have been easy to set right at the factory.
The only way I can see to square the Z axis assembly is to rotate the gantry beam. Two bolts on each side hold the beam to the vertical side plates. These bolts go through holes in the side plates with no obvious slop in the fit. The solution I see is to remove the two front bolts, ream out the holes they went through, crank the whole beam/Z axis forward until plumb then insert and tighten those two bolts.
I also have a Meteor in my home shop, and it does not suffer the same flaws this work machine does. My Z axis is plumb. My gantry runs parallel to my front frame rail.
My point here is to check any new machine for plumb and square. In most cases flaws found can be corrected, and the accuracy of your work will increase.