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Bean: Short in the Z (vertical) Axis


#1

Hi I’m printing out some 10 mm test cubes. The prints are coming out around 10.15 in X and Y and 9.10 to 9.50 short in the vertical axis.
The build plate is Zeroed to the LCD screen.
I’m using Chitubox software as the slicer using the Anycubic Photon profile; Resolution: 1440x2560 Size: X68.4mm, Y: 120.96 mm, Z 150 mm, Type:LCD Mirror
layer height 0.05
Lift distance 5 mm
Speeds at 300 mm/min
Resin settings and times are the default green settings from the basic Kudo 3d Controller page.

Anyone have any suggestions on how to possibly fix this? I don’t think it’s a machine problem. All my prints are coming out ok they are just short. Or maybe they are stretched to much in X and Y?


#2

There may be an issue with steps settings in the Arduino controlling the motor.
Remove the tray(so that you avoid damaging it), and place a piece of transparency film or other solid film over the LCD.
Use the web interface to ‘home’ the Z-axis.
Then use it to move the platform to 10mm, 50mm and 100mm and at those points, measure the distance, on BOTH ends of the build platform.
Then step it down to 50, and again 10mm and do the same measurements at both points again.

you should have the same measurements on both sides(+/- a very small value as nothing is ever perfect) This should prove if it’s moving straight.
You should also have the same measurements both times you measure the 50 and 10mm positions(with the same silly small margin) Differences would mean it’s slipping somehow. Not good.

Home it again.
Add a 100gram weight to the top of the mechanism and move to the 10, 50 and 100mm positions, and do the same measurements.
Differences would indicate definite slipping. Either the motor isn’t getting enough power, the coupling is slightly loose, or the axis needs lubricant. (You want a dry lube. Really. Graphite works. At worst, rub a #2 pencil on the threads… )

If the numbers ‘scale’ (a 0.5mm error at 10mm ends up as 5mm error at 100mm), there’s most likely a setting that hasn’t been set up right. (Number of steps per mm)


#3

If you are printing the cube directly on the build plate it might be off. My bean skips or compresses the first few layers. It will always come out short in the Z direction. Try printing the cube on a raft or with supports and then measure it again. The raft/supports will get shorted a little but the cube should come out right. Think you’ll find the Z-axis has the right scale in these cases. Also try using the built in slicer/support generator for comparison to Chitubox.