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Setting Z Offset Not Working Right...
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(01-13-2022, 03:29 PM)coaxfun Wrote: I'm going to try to be concise, because this one is beyond me.

So I first got the printer, calibrated the z offset, and printed the rook.  When I hit print, it went to the offset, and started printing.

Fast forward to a few prints later, when I go to print, it brings the print surface all the way against the lcd and seizes the motor.  At first, I thought it was just getting to low.  I recalibrated, and the same, again and again.

I had a hunch I knew what it was doing, so I tried a test; here are my steps exactly.


  1. loosened the two screws on the print arm.
  2. clicked home on the manual motion control.
  3. raised the arm by .1mm until I could move the paper on the lcd.
  4. did NOT tighten the screws on the print arm.
  5. set the z offset.
  6. raised the print arm to 15cm
  7. selected a file to print to test arm motion.
The arm comes all the way down, back to home, does the home test up and down, THEN goes to the offset.
Why did it start doing this all of a sudden?  When printing, shouldn't it only return to the offset?

I tried the above again but set the z offset to 1cm above the lcd surface and same thing.  It goes to home, then goes to the offset.  It makes absolutely no sense.

From looking around the web, it apears I'm not the only one that has experienced this problem.  Is there some solution that just isn't getting shared?

Your alignment procedure is flawed because of the printer's basic functioning. There are two "zero" positions used by the printer, one physical determined by the hardware limit switch, and one logical attained ONLY by the firmware's interpreting a gCode "goto 0" command--and this only after the Z-axis has been dropped to the physical "zero". Your process of raising the Z-axis without the screws tight will cause the platen to push down into the LCD when the printer attempts to "get it's bearings" by dropping to the physical (limit switch determined) "zero" position.

Going "home" and rising to the "offset" (Z=0 setting) is how it works--it has to go the physical home to figure out where "zero" REALLY is, it has to do this to determine absolute "zero". It can then do the math, and determine how many lead screw turns are needed to move to the logical zero "offset' position when commanded to do so.

The alignment process should be as follows:

  1. loosen the locking screws;
  2. lower the Z-axis to the "home" position (with a sheet of paper over the LCD);
  3. press down lightly and evenly on the platen;
  4. tighten (firmly, these are not lug nuts) the locking screws--front screw first;
Done... Do NOT raise the platen manually or use the "Z=0" function--it is not needed except in unusual situations to compensate for odd models and long-term creep. It is NOT a needed part of a standard alignment and if it were not exposed to the average user many people's printing experiences would be much improved.

See my posts here for more the "Z=0" function and my exchanges with Elegoo support re: same...
-cliff knight-
[Image: 816-20120803-wide800.jpg]
paladinmicro.com
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RE: Setting Z Offset Not Working Right... - by cliffyk - 01-14-2022, 08:58 PM

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