The Z tubes keep rubbing on one side of the table when moving in the Y dir. This occurs towards the end of the table. The table is a sheet of ply & yup is it’s perfectly square.
I’m thinking the LowRider is out of square even though I measured each X- tube distance from Y-Axis bracket to bracket on both fore and aft X-Tube.
Q. Is there a particular method one uses to square up the entire LR machine ?
Assembly - V1 Engineering Documentation
You may want to repost in the LR forum to see if anyone has additional tips.
good call… sorry bout that
No worries, happy I’m occasionally useful. 
I, on the other hand, am infrequently helpful…
If you’re looking for your “z tube” to get a table rub, look under massage parlors, not machine cutters. Things could get messy, in the screamy, traumatic ways. Well, more likely to…
More helpful all the time experience helps everyone 