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How to cancel automatic Z calibration before every print?  

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Renan Teuman
(@renan-teuman)
Active Member
How to cancel automatic Z calibration before every print?

Hello All,

My prusa has been automatically calibrating 9 points for the Z every time I send a file to print. I was wondering how I can stop this from happening. 

 

Thank you!

R

Posted : 02/06/2022 6:44 pm
Neophyl
(@neophyl)
Famed Member
RE: How to cancel automatic Z calibration before every print?

It’s what it’s supposed to do. The number of points that mesh levelling is set in your firmware, sounds like you still have it set to 3x3, for reference 7x7 is better.
However the process itself is set in motion by a specific gcode command. That command is in the printer profile as part of the slicer. It’s in the custom start gcode section. You could remove it and save a new profile and once removed it won’t do the mesh levelling, but that will make your first layers not very good once it’s removed. 

Posted : 02/06/2022 6:51 pm
jsw
 jsw
(@jsw)
Famed Member
RE: How to cancel automatic Z calibration before every print?

It's much better to have the machine spend less than a minute to recalibrate prior to each print than to lose several minutes (hours or more) with a failed print.  I have 7x7 set on the Prusa and I consider it to be time well spent, as in 49 probes instead of 9.

My other printer (Ultimaker) has a very similar multi-point 'sounding probe' at the start of each print which takes about the same amount of time.

Many printers do something like this.

Posted : 02/06/2022 6:58 pm
Dave
 Dave
(@dave)
Eminent Member
RE: How to cancel automatic Z calibration before every print?

@Neophyl is correct.  The calibration allows the system to figure out and correct the minor height variations that exist on your platform.  It's physically impossible to have a perfectly level Y-surface.  Some are warped more than others.  I actually had to switch to the 45 point calibration method to account for 3-4 spots on my carriage.  Adds 30-60 seconds to the print, but it beats getting failed prints!

Posted : 02/06/2022 6:59 pm
Renan Teuman
(@renan-teuman)
Active Member
Topic starter answered:
RE: How to cancel automatic Z calibration before every print?

Thank you all for your replies!

Posted : 02/06/2022 7:11 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: How to cancel automatic Z calibration before every print?

From some years of experience with the Prusa print bed, I can only recommend pausing the printing plate at the set temperature for approx. 10 minutes before starting printing and then performing the 49-point mesh leveling.

Each print bed warps (more or less, approx. 0.1 to 0.3 mm) when heated, which the firmware tries to compensate by using a mathematical algorithm (Lagrange or bicubic interpolation). I have not checked how reliably this interpolation works with the Prusa firmware, but it works just fine with Klipper and Duet (RepRap).

wbr

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 02/06/2022 7:53 pm
jsw
 jsw
(@jsw)
Famed Member
RE: How to cancel automatic Z calibration before every print?

I always pre-heat the machine to ABS temperature and let it sit for at least 15-20 minutes or so when doing ABS prints.

I will occasionally do the same for PLA and PETg prints, but usually do not.

It's just one of the 'attention to detail' things I've learned to do for the best ABS prints.

One observation I know I've reported on before is that when I do PLA and PETg prints, the machine will very seldom 'double tap' when doing the bed leveling, but when doing ABS prints and letting the machine heat up to ABS temperature, it will frequently double-tap once or twice in the rear two rows, leading me to believe that there is a small but significant thermal distortion due to the higher heat on the bed.

Posted : 02/06/2022 8:26 pm
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