Need help with Z axis offset issue after auto leveling. Marlin V2

Hey peeps! I have a P802ma (ANET A8 clone) that I updated the firmware from Marlin 1, to Marlin 2.0.x (latest). And I've been trying to get all the kinks worked out.

So far I have everything set up to the point where the coordinates all seem correct, and the print area is correct and such.

The issue: if I restart the printer and attempt to print, the nozzel is about 10mm above the bed. BUT if I run auto leveling, it corrects it, and prints properly.

Anyone have any idea what is causing the discrepancy??

I'll provide any Marlin config files if you need to look at them.

when u start print, the first thing that happens is a G28, home all. 10mm sounds like an after homing backoff. When it starts printing, the first thing it does is a G0 Z0.
If you do a bed level and it works, then I would GUESS that your bed position is not stored and is reset each time you start a print. U need to do a bed level then do M500 to store that setting.

Quote
ruggb
when u start print, the first thing that happens is a G28, home all. 10mm sounds like an after homing backoff. When it starts printing, the first thing it does is a G0 Z0.
If you do a bed level and it works, then I would GUESS that your bed position is not stored and is reset each time you start a print. U need to do a bed level then do M500 to store that setting.

Oh, so bed leveling corrects the offset, but I need to store it?

Ok, I'll try that and get back to you, thanks!

I'm not saying BL corrects the offset. If it works when you do a BL then what is stored in the EEPROM is wrong. If you do not do an M500 the new info won't be stored and the "defaults" will come back. The defaults, where ever they came from (probably your config files) are wrong.

Quote
ruggb
when u start print, the first thing that happens is a G28, home all. 10mm sounds like an after homing backoff. When it starts printing, the first thing it does is a G0 Z0.
If you do a bed level and it works, then I would GUESS that your bed position is not stored and is reset each time you start a print. U need to do a bed level then do M500 to store that setting.

No dice =(

I did a bed level, sent the code M500 to save, tried a print which worked fine. Then restarted the machine and without doing a bed level again, its still about 10-12mm off the bed...

Any other ideas?

I do notice that the bed leveling data appears to show this offset, but I'm unsure what to change in the Marlin firmware settings to correct this

Bilinear Leveling Grid:
0 1 2 3
0 -10.035 -9.882 -10.067 -10.442
1 -10.027 -9.965 -10.117 -10.487
2 -10.062 -9.912 -10.082 -10.472
3 -10.005 -10.140 -10.122 -10.502

post your configs
what is set to 10mm
it would be good if you flagged the lines that you changed in your configs.
It makes it easier for you to upgrade and someone to scrutinize it.
I use //**

Quote
ruggb
post your configs
what is set to 10mm
it would be good if you flagged the lines that you changed in your configs.
It makes it easier for you to upgrade and someone to scrutinize it.
I use //**

Here are the config files... as for what I've changed, I've fiddled a lot and don't really remember it all.

I set it to Fixed Z probe, I set the nozzle offset values, turned on bilinear bed leveling... and changed the Z_PROBE_LOW_POINT because it would stop the bed leveling from not making it all the way down with a "Probing failed" error.

The rest was a preset on the Marlin website for the Anet A8.

Edited 1 time(s). Last edit at 06/09/2020 06:01PM by SagiC.

I don't see anything outstanding.

try changing this and see what the effect is
#define Z_MIN_POS -10

I would start with new config files and change what is necessary and flag them.

Then add the "options" to see where it breaks.
Many things can be tweaked via the display or app and gcodes or mcodes.
It is a lot quicker then reflashing.

My ramps board is not compatible with endstop interupts so disable it till you get this fixed.

I will try fiddling with that setting and see if it effect the offset

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ruggb
My ramps board is not compatible with endstop interupts so disable it till you get this fixed.

what do you mean here?

I don't think this is an issue, but it is an option. Do not enable options till you get this working on basics.

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ruggb
I don't think this is an issue, but it is an option. Do not enable options till you get this working on basics.

Good news!

Z_MIN_POS -10 was the problem =)

I changed it to 0, and It now starts where is should, even without bed leveling.

Thank you for your time!

great news, you are welcome.