[BUG] Incorrect behavior when using z-probe

ksa-real commented 1 year ago

Did you test with a precompiled firmware?

Yes, and the problem still exists.

Bug Description

I have a generic 3d Touch sensor. First, by pointing to the same point at the bed I found and set in the "Probe settings" the X and Y probe offsets: -41.5 and -10.8. The difference of -3.8mm compared to the default -7mm is due to using a printed bracket: https://www.thingiverse.com/thing:4462870/files (V3_probe_mount.stl).

Then I went to Prepare->Z Probe Wizard (Probe Z offset was 0.00) and did Auto-Home. The final position was z=5.00. I deployed the probe (M401) and moved to z=0.00. The probe was well above the bed. This was already unexpected. Isn't Z-offset equal to position of the probe trigger point? As such moving to z=0 with probe z offset=0 should make the probe touch the bed.

Then I removed the software endstops (M211 S0) and started slowly moving down in 0.1mm steps. The probe touched the bed at -3.6mm and triggered at z=-4.98 (I switched to 0.01 steps after -4.9). So z is incorrect and is 5mm less than it is supposed to be.

Bug Timeline

I just installed 3d Touch probe and new firmware (Ender3V2-422-BLTUBL-MPC-20230809.bin instead of Ender3V2-422-MM-MPC-20230805.bin)

Expected behavior

I expected the probe to touch the bed at position z=0.

Actual behavior

It touched the bed at position approximately z=-5.0

Steps to Reproduce

See description

Version of Professional Firmware

Marlin 2.1.3 MRiscoC Ender3V2-422-BLTUBL-MPC, based on bugfix-2.1.x (Aug 9 2023 21:48:38)

Printer model

3V2

Electronics

4.2.2

Add-ons

3d touch

Bed Leveling

UBL Bilinear mesh

Your Slicer

None

Host Software

None

Additional information & file uploads

No response

mriscoc commented 1 year ago

With a Z probe offset of 0 (M851 Z0), Z at 0 (G0 Z0) will move the Z axis to the probe trigger point.

ksa-real commented 1 year ago

It doesn't. It moves 5mm above the triggering point. I suspected that maybe some EEPROM value is accidentally used. But resetting the settings to default and doing the above procedure didn't help. It looks like printer is going 5mm up twice: 5mm implicitly (i.e. z=0 on screen after that) and then 5mm explicitly (z=5 in the end).

mriscoc commented 1 year ago

Tested and it works as intended in current release Ender3V2-422-BLTUBL-MPC-20230809.bin

G28 Z ; home Z
G0 Z20 ; move Z to a safe position
M851 Z0 ; set probe Z offset to 0
M401 ; deploy probe
G0 Z0 ; move Z to the trigger point

ksa-real commented 1 year ago

What I just tried:

Turn on the printer (no sd card or USB cable inserted)
Control->Restore Defaults
Control->Save settings
Reboot printer
Prepare->Z-probe Wizard -> Auto Home Printer now is actually in the correct position! I.e. z=0 <=> we are at the trigger point.

Now:

Prepare->Z-probe Wizard ->Move Z to Home Printer now 5mm above expected position. I.e. it reports "z=0" but is 5mm above the trigger point. Is that expected? Maybe I just don't understand this option.

Now, if I try - Prepare->Z-probe Wizard -> Auto Home it moves 10mm above the trigger point and reports z=5

mriscoc commented 1 year ago

Control->Restore Defaults

Reboot printer

After restore defaults, save settings.

Move Z to home will move Z to the trigger point + Probe Z offset.

ksa-real commented 1 year ago

Control->Restore Defaults

Reboot printer

After restore defaults, save settings.

Move Z to home will move Z to the trigger point + Probe Z offset.

I've done that, forgot to mention in the steps. Fixed.

ksa-real commented 1 year ago

Interestingly, that time when it worked it did probing twice: the first time it was pretty quick and the second time it was slower. Now, I see the printer doing probing only once. In such situations, there is an extra 5mm offset. Now, even if I try to reset and save settings, I still see the same behavior with an extra 5mm offset.

mriscoc commented 1 year ago

Sorry but I can't reproduce your issue here. Maybe there is a problem/compatibility issue with your probe.

ksa-real commented 1 year ago

This is a video: https://photos.app.goo.gl/aSPLHBq744bAY4Bu9

I see that the probe is flashing after the first probing attempt. Not sure if that means it failed to deploy the second time.

mriscoc commented 1 year ago

The blinking indicates some problem with the probe, sometimes it is a white wire loose connection.

ksa-real commented 1 year ago

Closing this for now. There is certainly some problem with my probe, likely hardware.

ksa-real commented 1 year ago

Just in case someone has the same issue: in my case the probe doesn't seem to support high-speed probing mode. I had to uncheck the "High-Speed mode" which is ON by default.

github-actions[bot] commented 10 months ago

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.

mriscoc / Ender3V2S1