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Z Axis Height Calibration
#11
I still haven't gotten around to doing the video to show this.

Here's what happens...

Level the build plate however you choose to.  Now, with no resin in the vat, jog the z axis to home and you'll see that the build plate and carriage both stop at the same time, but as soon as resin is introduced, home the build plate again.  What you'll see if you watch closely is that the build plate will stop, yet the carriage will continue to move down slightly.

When the offset is done, the build plate and carriage will go to the trigger point, then the carriage will raise back up to the offset amount. 

Not sure on the formula, but the Mars does use a TR8x2 lead screw, so the S0.000625 would be correct.  That gcode config file is the original that was just decoded to english and not the chinese descriptions.
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#12
Thumbs Up 
Thank you so much for this. Process makes total sense and worked perfectly. One of my mars was losing 1.4mm, the other 1.0mm, and both print *perfectly* now. I'm so glad we finally have a good solution that doesn't involve "just print on supports" or "get a hex wrench..."  Big Grin
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#13
(10-21-2019, 07:48 AM)mckeemorology Wrote: Thank you so much for this. Process makes total sense and worked perfectly. One of my mars was losing 1.4mm, the other 1.0mm, and both print *perfectly* now. I'm so glad we finally have a good solution that doesn't involve "just print on supports" or "get a hex wrench..."  Big Grin
Glad to be of help!
And still.... If you get in contact with Elegoo they provide a modified motor in a very friendly manner.

And by the way.
Although this minor flaw I take the MARS to be a quite perfect printe and am very happy with it...
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#14
(10-21-2019, 07:48 AM)mckeemorology Wrote: Thank you so much for this. Process makes total sense and worked perfectly. One of my mars was losing 1.4mm, the other 1.0mm, and both print *perfectly* now. I'm so glad we finally have a good solution that doesn't involve "just print on supports" or "get a hex wrench..."  Big Grin

Just to clarify which method you used...
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#15
My first publication.
My first print with the Elegoo Mars showed me that I had a deviation of 1.6mm at the calibration cube in the Z-axis.
After I noticed that the Elegoo Mars has only a fixed holder for the light barrier for the Z-axis I decided to create my own adjustable construction.
After the production and the assembly of the unit shown here I could adjust the Z-axis exactly.
Note:
For the exact adjustment I took out the resin container and put 2 sheets on the LCD. Then I adjusted the holder so that it runs out without any force on the Z-axis.
Then I let the Z-axis move upwards by 0.1mm and set Z=0 via the menu item Set.
The following calibration cube had a measure of 20.01mm, this was repeated several times with the same result.
I hope that this construction can also help others to set the perfect Z-axis.
Suggestions from you are welcome.

STL-Files at Thingiverse.com

https://www.thingiverse.com/thing:3933877

Translated with www.DeepL.com/Translator
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#16
had an interesting experience trying the z calibration from the original post (.zip file) here.
i printed a cube in the center and also one near each corner, just to make sure i don't break the calibration anywhere on the plate.
they were mixed, 0.9 to 1.5mm off, but i didn't want to re-level since its been working well, so i just used the smaller 0.9mm to change the zeroing with.

i followed the procedure, printed the .gcode enabling the zero option, removed build plate, homed, moved it up by 0.1 increments 9 times then hit the z=0 button.
re-printed the 5 cubes, and one didn't print.  probably due to my lack of calipers (so 0.9 was a bit too much in that corner), which i hope to fix some day.  ok, the rest were indeed much better heights, so i figured i'd just adjust back 0.2mm. 

i removed build plate, homed, moved _down_ 0.1 increments twice, then hit z=0.  reprinted the cubes... they were all back to the original heights, 0.9 to 1.5mm off.
i suspect there is something else going on introducing variability in the Z axis? or does the Home button not go to the last z=0 position?
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#17
When you did it the 2nd time and did the first step of homing the build plate, then did the 0.1mm down 2 times, that actually took it .2mm lower then the home position.

What you would have wanted to do is do the homing position, then instead of the 0.9mm up, just do 0.7mm up, then tapped the z=0 to reset.
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#18
The problem is not directly the set=0 but that the reference point is not equal to the build plate zero point, but much more important that the drive motor and the damper give way differently, especially when the axle drives on a block. That's why I developed the adjustable Z-axis to adjust the reference point so that NO more force is applied to both the engine and the damper. With 2 sheets set the light barrier as distance and then go up 0.2mm and with SET=0 set the build plate.

Translated with www.DeepL.com/Translator
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#19
Hello everyone,



my english is not the best but i try my best to explain what i found out about the problem.

I postet two videos on Youtube, where i show the problem.





I mounted a dial indicator to my Elegoo Mars (i bought last week) to check the accuracy and to calibrate the steps/mm.

The Limitswitch to Zero the Buildplate works perfect, the Problem is that there is backlash in the thread, the flexelement (can't understand why they use this) or the motor.

Because of this there is "no" movement for the first 0.4mm as you can see in the second video:


At first i try to remove the flex element and test if this will reduce or remove the problem.

Later i report.
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#20
Ok guys i think i found the Problem and it give us the answer why some of us has this problem and the others not.
At disassembling my printer i realized the load on the rail is much to high, the Carriage is moving but it needs to much force and this force pushes back in the flex element and in the motor.
After adjusting this the printer moves very accurate.
Like you can see on this video:
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