Ok, this is about the best I can do to eye-ball the perpendicularity of Y to Z-Plate-face … is there anything else you have in your bag of tricks to get this dialed in better?
I also have a mechanical dial but no mounts or whatsoever to clamp it. It would be very interesting to mount it to the extruder, at the back of it, and check the X axis against the edge of the bed.
I find it pretty frustrating that it is very difficult to make small incremental changes in this kit. You have to turn the printer on its head, un-fasten the 2locking nuts on one side of the Z-Plate and the single nut on the other side, turn it minutely towards front or back, then tighten it again, turn it around, use square, check … do this until you have the Y lines on the bed parallel to Z Plate. I don’t even know how relevant this is as I need the X-Rods to be parallel with the lines on the bed.
Does it really have to be perfect? As long as the bed is level idk if it really matters if it’s perfectly square. I highly doubt mine is. My printer is nothing more than I lightly polished turd and I can get halfway decent prints.
Having recently built an MK2S kit, I can attest to the auto-correction of the Prusa calibration routine, but it will fail if the deviation is too great. It will taunt you if the deviation is within auto-correct limits.
Florian Ford, the best place to start is the X/Y bed assembly. Ensure that it is square by measuring the diagonals of the assembly as accurately as possible. Make adjustments as needed to have the diagonal measurements match, while keeping the left/right/top/bottom distances the same.
What has caused me trouble sometimes is that Y-axis motor mount may flex when doing autocalibration. Nothing that a wooden shim cannot prevent but a source of frustration when it happened.
