Well, I am circling the drain, and I have a workaround that is working for my simple test.
The Z rails (the 11" pipes) are square to the table top as long as the wheels are in line. After moving forward and backward, it gets misaligned. I thought I could fix that by loosening the connection on the long pipes, but duh, I can only make them shorter, longer, or trapezoidal by moving those. But they are a parallelogram. I think I need to reprint the little pieces in the middle of that joint, at least, maybe those entire joints.
But, I do have a neat workaround. Like I said, the root problem (I think) is that as the wheels turn, it’s getting off track. So I ripped some 3/4" plywood into some strips, and installed them 1" from the edge of the table. Then I loosened the long pipes, and pulled it together so the wheels were touching those strips. I could do it on the bottom too, but since there aren’t pipes pulling the bottom together, I’m not sure how much it will help.
Photo of the hack/track:
Before:
After:
( It’s the middle one, it’s a little blurry, but it’s smooth IRL )
Something is not square. I have a suspicion that it’s either the printed joint, or one of the screws that holds the wheels on is bent.
I can tell from where the hack/track is touching the wheels that the front left and rear right want to move past the track. There is a small gap in the other two wheels. The original cut edge was pretty sharp, so I rounded it over with some sand paper before installing it to try to reduce the wear on the wheels.
I don’t think the hack/track is the right final solution, but I have something I want to cut today and I think this will get me moving until those parts are reprinted.