Square enough or not?

Mostly Printed CNC - MPCNC Troubleshooting
1

Thank you for letting me ask questions and helping me fix my mistakes!

My MPCNC has a frame size of 30 x 18 inches, most of my plans involves less than 6 x 6 inch cutting areas.

Using the pencil mount, I can draw a 100x200 mm (~4 x 8 inch) rectangle and diagonals differ by an 1/8th inch. I am thinking this is not worth dealing with, but want everyone else’s opinion.

Should I fix the squareness or move onto killing foam? Am I asking for problems later?

Thank you

2

It depends on how much accuracy you need for the parts you’re going to cut. If it’s just decorative stuff, it doesn’t matter. If you make two parts that have to fit together perfectly, you may need to spend some more time on it. As long as you’re happy with the results, any difference in diagonals is fine. Nothing is going to break.

Note I am assuming that frame tubes are nicely parallel though. If it’s hard to move the router to a certain side of the workspace, there’s a chance that the steppers may skip steps there and ruin your work. But if you can move around the router by hand without too much effort everywhere then you’re good.

If you do want to correct the squareness but don’t want to fiddle around with the corners etc, check out this thread. You can make Marlin compensate for non-squareness. (Make sure that the Y axis gantry tube is perpendicular to the frame, and that the X axis gantry tube is the skewed one.)

3

Thank you for the response. I think I am going to fix this. I am super eager to start cutting, and I have lots of other things on my plate. I know this will bother me if I don’t fix it. I also know I could cut the things I need to cut, then fix it.

Thanks again.

4

Ok, I hope this helps someone. I stopped overthinking and fixed this in 10 minutes.

  1. I pencil to the Z and drew the largest rectangle possible by pushing the axis by hand.

  2. I then used a 12 inch square to draw a proper square line off the x axis.

  3. do the math on how far you have to move your feet over. In my case @12 inches I was 4 mm off square, therefor my 18 inch frame needed to move over 6 mm.

  4. unscrew the feet and redrill the holes 6 mm over.

Now my mounted pen tracks the “90 degree” line

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