Machine not square.

Hey guys. I’m having some trouble. My MPCNC’s frame is square. All my pipes are dead nuts. However, when I put on the middle assembly it doesn’t ride square. If I manually move the middle assembly to any one side then one corner is off from its counterpart by like half of an inch. It almost seems to me as if the middle assembly isn’t a true 90°. Any ideas? Thanks in advance.

And that applies to any side… No matter which side I move the middle assembly to. Hopefully, im explaining this correctly.

If you measure the frame diagonally (corner to corner) do you get the exact same measurement both ways?


if you are getting the same diagonal measurements, there is only the center gantry left.

I know it sucks but you need to rebuild it. In the instructions it says to check for square before final assembly. Take the center off with the tubes and the z axis, take all the long bolts out of the assembly and put it back together. check for correct (light) tension and square at each step.

It does suck but it pays off to get this right. Then before you start each cut verify it is equidistant from the corner blocks. The more square your assembly the easier that is.

So I measured lol…All my pipes are the same lenth and yet diagonally I am a half inch off… How would I fix this?

You have made a parallelogram. Have a second look at the directions and mount the feet with the diagonal dims correct.

That’s definately the problem… I also should have screwed the legs down. I was going to wait to do it, but it appears it has to be done now…

Update: I now have a perfect rectangle with the feet secured to my workbench. I put a carpenters square against the backside of my middle assembly and its slightly out of whack. For the life of me (even by taking it apart and starting fresh) cannot figure out why. The only thing that doesn’t seem right is the bolts that secure the bearings to the front side of the xyz part seem to dig into the xyz parts and push them out. That and the xyz part seems to do that on its own by not allowing the xyz part from sitting forward enough on the sides where it bolts together. I’d post pictures but every time I try it tells me they are too big.