Mendel squaring axes

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Mendel Build Documentation


Find a flat, horizontal surface to set your printer on


  • Hang a plumb line from the top of the Z-bar to make sure it is vertical.
  • If you have followed the jigging procedure carefully this axis will be square.
  • However, if not, perpendicularity is achievable by the following steps:
  1. Check that the surface which you're measuring on is horizontal.
  2. Adjust the lengths of the frame sides by slackening/tightening the nuts at the frame vertices to change the shape of the triangle.
    • You will need to loosen the Z-bars before the triangles will change shape.


Use the RP spacer: bed-height-spacer-31mm_1off [1] to get a consistent distance between the Y-bar and the underside of the bed for all four corners.


  1. Lower the nozzle to one corner of the bed, leaving a nozzle/bed gap thin enough to slide a piece of paper into.
  2. Remove the paper.
  3. Disengage the Z-belt by loosening the bearing on the tensioner bracket.
  4. Slide the carriage to the other end of the X-axis and rotate the relevant Z-axis leadscrew until the nozzle/bed gap is the same (using paper again).
  5. Take the carriage back and iterate until the gap is identical.
  6. When happy, re-engage Z-belt.

X-Y check

Move the nozzle to all four corners of the bed. Any discrepancies can be remedied using the four corner adjuster bolts on the bed.

Smooth Rod Method (SRM)

To avoid crashing the nozzle into the bed, you might want to use SRM. [2] It will smooth out the measurements if there happen to be a tiny dent or a bump on a measure point. SRM is also a bit faster, and theoretically more reliable than paper.

  1. Cut a ~10cm piece of 8mm smooth rod. (Or any equivalent smooth rod you have available).
  2. File off any jagged ends to ensure it rolls properly.
  3. Move the z axis so the nozzle is 8mm above the bed, and you're just able to roll the rod under the tip.
  4. Do your measurements as described above, while rolling the rod under the nozzle tip at the measuring points of your choice.

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