First layer calibration - My Way

Based on the excellent first layer calibration method from JeffJordan on the prusa forums.  He provided the object as gcode, with some helpful beeps built in. Designed to check two z heights, and cross compare.  

My FirstLayerCalibrationObject:

• Faster z-height experiments
• Rectangular shape, so each test lasts approx. the same duration
• Large enough for up to 6 tests
• No Beeps
• 2 layer heights for walls and skirt, for easy cleanup.

Built In Calibration

Run the normal first layer calibration from settings, and put your eyes below the print head so you can see the nozzle.  Get the nozzle close enough to smush the filament but not crash into the bed.

At best, eyeballing like this will give you a basic first layer calibration that is within +/- 0.2mm.  This is enough for most prints.

Better Calibration

Now let's use the FirstLayerCalibrationObject.3mf

Open the 3mf project and select your printer / settings.  Set the following:

• 0.2mm layer height
• 2 skirt height

Print on your printer, and after the skirt starts printing, hold the knob until the Live Adjust Z menu appears.

Write down the current z-height, then start adjusting. Allow the printer to run for about 1 - 2 cm of the object, then select a new z-height number and write it down.  Keep repeating until the object finishes.

When complete, wait for the bed to cool, remove the calibration object, and do some tests!

• Push on each section with your fingernail and bend to test for cracking
• Hold up to the light to check for holes
• Look for wavy or straight patterns in each line

Mark the z-heights in your notes with good adhesion and strength.

Repeat again, narrowing in on the z-heights you like.

• First Tests: +/- 0.100 mm
• Second Tests: +/- 0.050 mm
• Third Tests: +/- 0.025 mm

You can keep going if you like, but that's generally where I stop as good enough.  I can't really tell the difference below +/- 0.02 mm

References:

• https://help.prusa3d.com/article/first-layer-calibration-i3_112364
• https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/