Primo x and y axis do not get square

[Markus1]

Hello everyone I have a problem with my mpcnc Primo.

I can not get the x and y axis to be square after putting the rails through my core even if I tighten down the tension bolts. The tension bolts do basically nothing.

Information about my mpcnc:

I have the old 3D parts of the Primo where there was to much slack in the core clamps so I printed the resized clamps.
I use 25mm rails.

A small recap what I have tried:

I looked if my cnc is squre and it is.
I also looked at the Truck Squaring step again.
I tried to tighten down the tension bolts very hard but it give me only around 1 mm better accuracy.
I have also rotated the rails to make sure they are not bent.

[Zymurgist (Thomas)]

Hi,
I am building my own, but I also found that the tension bolts made little difference. I measured diagonals very carefully, but it is unaligned when the core is put on. when I asked about it here was the discussion:

mind the last post. I am setting up my wiring this weekend, haven’t worked on this build in months, but maybe this can help you too:

Primo Build - unable to align once putting on core

I have an update Thomas, I went out to the garage and there is some play in the axis; I can move it so that it is square. I loosened the belts n both sides, and tightened up the side that was “long” to pull it closer to square. It is not perfect, but it is better. I am now down to 3mm off. I think that once I wire it up the motors, belts, and dual end stops will take care of things. I think that for my first test run I will put a pen in the tool holder and try a spiral like this (but a thin…

here are at least three contributors to the alignment: the belt tension, the length of the gantry, the alignment of the feet. Assuming that the feet are properly aligned via the diagonal checks and the belts are adjusted, the next thing is the length of the gantry. Here is how I adjusted that:

Loosened the truck clamps for the X-Gantry
Loosened the belts for the X trucks
moved the core to the X center and Y far end
measured the X gantry at each edge and shifted the trucks to get them lined up
tightened the truck clamps slowly (1/8th turns alternating, rechecking the distance, just until the conduit was resistant to turning
tightened the belts to their original slightly loose state
measured again
moved the core to the center of the area and measured again, everything is within 1mm now

[Markus1]

Thank you for your reply,

I have tried that methonde today and I found out that I can get one axix to nearly 0 mm with this.
But when I do that all of the error goes to the other axis so now I have a axis with 0mm and one with around 8 mm.
I think my core does not have a 90° angle because even If I try to force it into shape I can not get it to stay. My axis will just bend with the force because they wobble a bit not much but it is enough to tansfer the error form one axis to the other.

Do you know something I can do at the core to get it to 90°?

[Zymurgist (Thomas)]

MArkus,
Double end stops is what I am banking on… I will use the end stops, plus a firmware offset to square it. Then the stepper motors will bend the core so that it cuts square, and in the same location, everytime.

But again I haven’t finished my build yet. so little time lol