Alignment Issues ( possibly )

My mysterious misalignment is back…
(see images)

Alignment is fine in gSender but when I send it to the Long Mill and cut it, it’s crooked, does this mean my tables out of alignment and if so any tips on aligning the table or what should I be looking for to verify my tables out of alignment?

Thanks in Advance

It seems to have cut correctly but just at an angle possibly because the substrate was not placed parallel with the x axis?

Check your backlash nuts, maybe the left Y axis is too tight?

It could be what @engraver99 said but it could also be that one side of the X axis is further down the Y rail then the other side. If your machine is mounted square then you should be able to run the Y axis all the way back until it hits on both sides to square it back up. If you pay attention as you get close to the back you can see if one side hits before the other. If you have limit sensors you might have to turn off soft limits to be able to reach the far back side.

What @GettingStarted said could cause this if one is too tight and stopped that side from moving as far as the other at some point causing it to fall out of alignment.

EDIT: Modified Kevin’s image to show this situation.

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When I checked square the Y was out a bit on the right side, not sure how that happened but going to assume the backlash nut needs loosing a touch. Any tips on how loose or tight the BL Nut should be?

Thanks again for everyone’s help, honestly, I probably would have sold my CNC or at least thrown it into the nearest Lake if it wasn’t for this forum.


This is how I adjust my anti-backlash blocks.

Back the bolt out until you can feel the play in an axis by grabbing the steel plate that the respective block is attached to. You should feel the play as you try to move the axis back and forth by hand. If it’s quiet enough you can also hear it a little bit. Then I tighten the bolt a little, maybe 1/8-1/4 turn and check again. When the play is gone your all set.