[BUG] M600 resumes mid air Ender 3V2

[Vic152]

Did you test with a precompiled firmware?

Yes, and the problem still exists.

Bug Description

M600 resumes print mid air.

Bug Timeline

No response

Expected behavior

When print resumes after M600 - filament change - nozzle is at the height that allows the new filament to stick to the previous.

Actual behavior

When print resumes after M600 - filament change - nozzle is above the previous print. It prints in the air. to fix I have to lower Z from -1.5 to -1.95

Steps to Reproduce

Slice with layer change using M600

Version of Professional Firmware

Ender3V2-422-BLTUBL-MPC-20240125.bin

Printer model

Ender 3v2

Electronics

4.2.2

LCD/Controller

Stock

Other add-ons

CR touch

Bed Leveling

UBL Bilinear mesh

Your Slicer

Prusa Slicer

Host Software

None

Additional information & file uploads

xyzCalibration_cube_13m_0.20mm_215C_PLA_ENDER3V2.gcode.txt

[Vic152]

I in fact did not change the colour but just to illustrate the point.

[Vic152]

I found workaround by doing this:

;COLOR_CHANGE,T0,#34E92F
M600
G1 Z1 <-- relative to the layer
G1 E10

[PrintGoodCodeBad]

Vic152, thanks for this bug report!

mriscoc, thank you so much for your contribution to the 3D printing community! I hope to contribute something of this magnitude someday.

I have experienced a similar issue. I have an Ender 3 V2 with an Ender Extender 400XL kit (400 x 400 x 450) installed. I have a 4.2.2 control board but I will have to double check when I'm able to do so. I have been using Cura 5.2.2. I am using a post-processing script to add in the M600 filament change code at a certain layer height, but I do not currently know how to determine post processing script versions. The filament change behaves as expected until the print resumes, at which point the tool head appears to return to the print at too high / tall of a height. I initially thought it was possibly a retraction issue related to the much longer bowden tube for the extender kit, so I printed a and installed a direct drive modification, but I still have the same issue. I have a second stock Ender 3 V2 with the jyers firmware. It runs basically the same slicer settings, with the same Cura version, and same computer, and this stock printer with jyers firmware behaves as expected. I did check the G-code text, and it appears to have the same Z height command before and after the M600 filament change. So at this point, I suspect that the firmware could be handling the command in an unexpected way.

I found the following Reddit post where this issue and firmware was mentioned: https://www.reddit.com/r/Ender3v2Firmware/comments/yhi4wa/filament_change_effecting_z_offset/

For now, I reverted to Jyers and the print did not have the same issue. I would try and suggest a fix myself, but I’m not really a good coder…yet.

[Vic152]

My final G code was this. I found myself doing E step calibration, flow rate calibration, and Z offset calibration (after the previous two)

G1 E-100 F1500
G92 E0
M600
G1 E2.5 <-- extract tiny bit to compensate for filament change, will depend a little bit on the filament, temperature.

[PrintGoodCodeBad]

Thank you for your reply.

I did more tinkering and I believe I know the issue. For me, I no longer think the firmware is an issue. To close the thread, I essentially think the issue is having an extended x gantry being lifted on only one side. For the M600 command, the gantry lifts, filament is changed, and then comes back down. I measured around two full millimeters of play on the right side of the x gantry by lifting up and pressing down on it. Therefore, there has to be some z-axis height hysteresis (after it completed the process of coming down from the filament change, it must be higher than when it was continually lifted up during the print) which I believe causes the problem. When I simply pushed it down after the filament change, the print appeared fine. Sort of annoying, but I can live with it for now.

[Vic152]

I think we can close this. It's good to have some detailed record for community.