Hello,
I don’t want to make a new troubleshooting point, because I have the same problem.
I’m German, but I’ll try to describe the facts in english, sorry for the errors in my text.
My MPCNC has the overall dimensions 800x930mm, I’m supporting the middle of all tubes, they are 25mm type. In the past I disconnected the supporting, but no change (I want to say, they create not the problem).
The dimensions in the diagonals are 101,6cm and 101,7cm (measured at the upper housing corner, near to the tubes), so only 1mm difference that means lower than 0,1%, for my opinion is this really good.
The squaring-error is approxomately 5mm between Y0 and Y1, and 10mm between X0 and X1 (hope you understand what I mean, X=930mm, Y=800mm). This is an other world when I see the difference in the diagonals.
I had the hope, that the belts will help to reduce these errors, but no change.
When the middle assembly is free, I made some checks with the integrated X- and Y-tubes over the complete length, and the squaring looks good.
When I integrate all parts then I get the squaring problem, it’s not necessary to fix the screws on the rollers (I made in the past a lot of things, and today I started again to find the error). In the past I 'd checked that I build the roller in the correct direction, so now the X-axis has on one side the standard and on the other side the mirror-roller, same on the Y-axis. Maybe there are some more aspects I could check here, but I found nothing in the docs.
The tension Bolts A are assembled but no force, only the bearing wheel has contact.
Today I disassembled the Z-axis, opened all screws from the X- and the Y-axis at the rollers, opened the 130mm screw and took a look if the big XY-burly-parts are to small (because of the 3D-printer), I found in a german forum this point. I had no idea to measure, so my idea was, when these parts are to small and I’ll open all screws, the lower tube must go up a little bit. But there was no tolerance in the X- or Y-tube. Nevertheless I integrated a washer between the two XY-burly-parts, at first thin one 0,4mm plastic, then 1mm metal and at the end 1,2mm metal. I saw with the last washer, that this was too much because the upper tube pressed up in the roller. For my opinion, it was not the right way, so now all washers are removed.
I’m not sure in which direction I can force the squaring with the 130mm screw, for my opinion only in the wrong direction.
In the moment I have no idea what to do. Normally I’m ready with the mechanic and the cable management (no force on the Z-axis with a dragchain), and in the next step I have to connect the cables. I prepared the double-endstop-solution (mechanic, switch, cable), but I don’t like to force the mechanic over this way. My plan was to use only 3 stepperdrivers TB6600, and the two X- and Y-motors are in a row. I made a plan to integrate all parts in a housing, but there is no room for 2 more TB6600. In the moment I spend no mechanical work in this housing, and I have the option for changing to a bigger one, but I’m not really interested to do this.
Hopefully, I get some more ideas from you to find the error, or points for solution.
Thank you, and best regards from Braunschweig/Germany
Thomas
The parts are printed with PETG, and I used high infill, I couldn’t say how much, because I used other parameters in CURA, but I’m sure more then 60% infill.