V wheels don’t line up with Y axis

Need some help getting setup… the upper v wheels on the right Y axis carriage plate do not align with the y axis extrusion. They extend about 1mm too far. The lower v wheels are aligned with the extrusion. The right Y axis carriage plate is not square with the x axis rail. The left side is better but still not square. To me it looks like the end of the x axis extrusion is not cut square and/or is not the right length. I measured the top length of the extrusion at 0.010” longer than the bottom length of the extrusion.

The machine is on a torsion box, and I followed the machine squaring instructions by loosening the bolts and moving the gantry front to back etc. I leveled the rails following mikep’s write up. I put a mag base on the z axis and the indicator against the side of the y axis extrusion. I moved the z axis up and down and the travel is parallel with the side of the y axis extrusion within .002”. So the x axis extrusion is square with the y axis extrusion (in the x-z plane) but the y axis carriage plate is angled 1/16” across the height of the y axis extrusion. This shows up when putting a square between the y axis carriage plate and the x axis extrusion.

Not sure where to go from here…


Some people have reported the cuts at the ends of the extrusions not being completely square. That may be the case here. A shim of aluminum can at the “short” end of the extrusion usually gets that sorted out.

I’d loosen the Rail, tighten the V wheels then re-tighten

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@mikep if I shim the short end to square it, it looks like it will take LOT of shim… not just a couple pieces of foil. And then I’m still over 1mm too long for the v-wheels to line up with the y axis extrusion?

I had a similar experience. In my case, I very carefully spent hours systematically filing the X-axis extrusion ends until they were square.
Since this process can shorten the extrusion to some degree, I removed the powder coating from the 16 Y-Axis end-plate holes to help allow for the “shorter” X-Axis.
Seems good so far.

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For those with an XL or XXL, what do you measure across the top from outside to outside of the y axes carriage plates? I’m at 40-5/16”.

@Luke I just tried that, didn’t change anything.

I take it you have the eccentric nuts fitted to the bottom of the carriage?

Can you measure the distance between the top and bottom holes? There might be a slim chance that they are not drilled correctly but I’ve never seen anything like this.

You could try flipping the X 180 too.

Yes, the lower v wheels, connnected to the eccentric nuts, are centered on the v in the extrusion, but this causes the carriage plate to bend inwards 1/16” inch at the bottom. My current thought is that the x extrusion is ~1/16” too long.

Ok with the right side eccentrics tightened so the v wheels are centered on the rail, but the carriage plate is bent inwards at the bottom, I loosened the left side eccentrics. This pushed all of the left side v wheels out of position to the left rail. See picture. I think that proves the x extrusion is too long…?

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