It should not be unless there are spacers missing somewhere on the gantry cart or z axis wheel assembly. Or camera perspective, because it is not taken directly on at 90 degrees. Have you tried surfacing the spoil board? If it is out of square, you will see it in the cuts.
It's out of square in the cuts, which is why I started looking. I can't find anything missing. I will say my v-slot wheels, half are tight and half just spin.
Ok, this is me. The uprights are square, but the x-axis is tilted. I fix this by "correcting the roll of the gantry itself". Does that mean by adjusting the eccentric nuts on the v-slot wheels?
What matters is a perfect squareness between imaginary vertical line through the router, and the imaginary XY plane. Loosen the end mounts of the X C-Beam and roll the gantry beam itself. The image shows exactly what I mean by roll of the C-Beam itself, its not a wheel adjustment, the beam itself is rolled out of square
Forgive me for being a newb, But there are 5 corner connectors, a triangular aluminum plate, etc. I don't see how any of these are adjustable... Maybe shims on the top X-axis c-beam where it attaches to the upright supports? That would "tilt" it...?? I don't see a way to adjust it otherwise...
There is some wiggle room in the mounts, the screw holes are oversized, you definitely can get a little roll out of it when you loosen a couple strategically The 90deg plate might be constraining it relative to the top cut-edge of the upright - and that might not be 100% square - just as example - would need to look at the problem to find root cause, but if the square says its rolled, it needs to be rolled the other way - regardless of the cause. Loosen up and try, check with the square. Otherwise, see the 2nd suggestion in that section of the writeup Cancelling out the roll, by purposely adding a little lean to the uprights. Less ideal, but still viable. If the plane is flat, and endmills intersects in perfectly vertically, that's the key - how its done - is mainly a case of building it square as can be - but as some tolerances stack up, one does what you can.