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[Solved] Mini Z axis have a non 90 degree via Y  

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Javacer
(@javacer)
Eminent Member
Mini Z axis have a non 90 degree via Y

Hello everyone!
Found a problem when printing tall details.
The Z-axis does not have 90 degrees with the Y-axis. It is tilted towards the screen.
A grounded metal part of the Z-axis may have come across.
Tell me how to fix the problem.

 

Posted : 07/03/2021 1:25 am
Javacer
(@javacer)
Eminent Member
Topic starter answered:
RE: Mini Z axis have a non 90 degree via Y

Nobody will throw any idea?

Posted : 08/03/2021 4:57 pm
Javacer
(@javacer)
Eminent Member
Topic starter answered:
RE: Mini Z axis have a non 90 degree via Y

Ok. Googled..

So. This is not possible with the specific physical design of the printer. The tolerances are very large, it is impossible to set right angles using the DIN 875/0 square. The accuracy class of frame fabrication can only be increased by altering the bed and the z axis on the CNC.
But! There is a software solution that the developers of Prusha for some reason blocked for the end user.

М852 https://marlinfw.org/docs/gcode/M852.html command allows you to adjust the angles of deflection in real time during printing.

Here it is
https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/b8bc6da0dcc4ce09650be46f23f646b28d9ff771/lib/Marlin/Marlin/src/gcode/calibrate/M852.cpp
And in the assembly header file it is commented out
https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/729d19fde4d22ec28616903a7a5abdcb4dda734a/include/marlin/Configuration_A3ides_2209_MINI.h

// Enable this option for M852 to set skew at runtime
// # define SKEW_CORRECTION_GCODE
#endif

Perhaps this will somehow affect performance, I can’t say with certainty whether there will be problems or not.
But. I rebuilt the firmware after measuring test prints with a different setting.

https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/729d19fde4d22ec28616903a7a5abdcb4dda734a/include/marlin/Configuration_A3ides_2209_MINI.h

I have allowed the use of a piece of code related to coordinate recalculation.

#define SKEW_CORRECTION <- made changes, removed //

#if ENABLED (SKEW_CORRECTION)
// Input all length measurements here:
#define XY_DIAG_AC 282.8427124746
#define XY_DIAG_BD 282.8427124746
#define XY_SIDE_AD 200

and put my measurements into variables.

I used last stable version from github.
Build firmware

python utils / build.py --final --generate-bbf --final --bootload yes

I uploaded the .bbf file to the USB flash drive and flashed it.
The print completely satisfied me.
It remains the same to align in Z.

Of course I broke part of the motherboard 🙂 as recommended on the site.
Guarantee? ) Why, if it is impossible to print exactly!

Posted : 08/03/2021 11:25 pm
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