R2 does not keep z calibration

Hi

So I solved my previous issue where the printer would try to lower the bed thru the bottom of the printer when starting a print, however I'm still having issues with the Z axis.

I go through the wizard and set Z, but when I try to print it starts off digging into the bed. I tried the fine tune z-offset, but it printed midair.

I updated my firmware to Marlin_1.1.6_RoboVersion_1.2.6 and the software is the latest Robo 2.0.0-r2.6.

These issues all started after a bad print. I had to replace one of the smaller timing belts, and now I just keep on having issues with Z.

I don't think it's a hardware issue, I never messed with the bed or it's mechanisms, just the extruder frame (took it out to replace the belt).

Any thoughts? Maybe I'm missing some simple troubleshooting steps.

 

See attached pic of the printer printing midair during the fine tune z-offset wizard.

 

1.2.6 - does not keep Z-Axis calibration
1.2.4 - causes the original issue of the bed lowering into the printer before a print, messing up the z offset
1.1.9 Beta - hangs on 'Preparing Printer' during z-offset calibration wizard
1.1.7-r2 - hangs on 'Preparing Printer' during z-offset calibration wizard
1.0.0 - this kills the machine lol

 

I'm getting all firmware update files from github.Robo3D Marlin releases (weird formatting because of the forum)

 

So here are the steps I took
Reset EEPROM

Home offset -20
Probe offset -20
Advanced variables (not sure if these are important)
S 0
T 0
X 8
Y 8
Z .04
E 1

I run the offset wizard, get an offset of -7.35

EEPROM now at
Home offset -7.35
Probe offset 0
Advanced variables
S 0
T 0
X 8
Y 8
Z .04
E 1

Reset EEPROM and put in -7.35

Probe is at 0 already


Try a test print

The nozzle heads towards the front of the bed as it does before every print, and digs into the bed. Then the bed slowly lowers as the nozzle moves left to right. The nozzle heads to the middle for the print and starts printing midair. It's just so weird.
I could get a video of this. It seems like I have a wandering bed issue.

 

So I've messed around with manually setting the offset, but it seems that the actual issue is the print bed lowering at the start of the print. See bellow image. That's weird right? No idea why it's doing that. It should not be doing that. Why is it doing that?



I can upload a video if that would help.

 

The most common causes for me are: The nozzle on the print head is loose. Dirt on the IR sensor. and if the print surface is not uniformly glossy the height sensor can screw up.

I can send you an R2 hex file to install that has no problems if you would like. I will have all of my upgrades. I need to know what your print surface is so I can send you a version with a corrected bed temp table.

 

K, I'll copy the code and post it here, and I would definitely try out your hex file Lance! My print surface is the standard one that came with the machine.

 

This has quite a few improvements such as 36 point bed calibration and 10 layer fade. If the height is too far off ( because I use a glass bed and E3D print head) you can adjust it in configuration .h

https://drive.google.com/drive/folders/1W-0ikEZfECKWoyjTN5EnqHHFZkHyLZUB?usp=sharing

Marlin version that I use

https://drive.google.com/file/d/1VJbKnYBNBaj2MGi5N9iI_ZXe1eGTvC6w/view?usp=sharing