search

MarlinFirmware / Marlin

Marlin is an optimized firmware for RepRap 3D printers based on the Arduino platform. Many commercial 3D printers come with Marlin installed. Check with your vendor if you need source code for your specific machine.
https://marlinfw.org
GNU General Public License v3.0
16.23k stars 19.22k forks source link

[BUG] Issues with Z-Offset when using BL-Touch (Marlin 2.1.2.4) #27407

Closed GER-HerrS closed 1 month ago

GER-HerrS commented 1 month ago

Did you test the latest bugfix-2.1.x code?

Yes, and the problem still exists.

Bug Description

I have a modified CR10-V2 with DirectDrive, BTT SKR2 board and BL-Touch.

I have had the problem I am describing here for a few versions (I can't remember exactly which one it was, I think 2.1.2.2).

At the time I had tried the current 2.1.0 bugfix and had no success with that either.

However, since it is not a new feature but a standard function, this should actually work and so I resignedly decided to wait for a new release version.

Now I am using 2.1.2.4 and the error has remained.

That makes me more than suspicious.

Maybe it is an error in my config files (although it worked like that in earlier versions?).

Maybe it is a bug after all.

The problem:

Bug Timeline

2.1.2.2

Expected behavior

I expected BL-Touch Trigger point + Z-Offset to position the nozzle fine for first layer.

Actual behavior

My Z-Offset seems to has no influence at all.

Steps to Reproduce

Just try to use BL-Touch sensor with correct Z-Offset using Marlin 2.1.2.4.

Version of Marlin Firmware

2.1.2.4

Printer model

Creality CR-10 V2

Electronics

BTT SKR2, Bondtech DDX v3 and Mosquito Hotend

LCD/Controller

Standard LCD from CR-10 V2

Other add-ons

Filament runout sensor

Bed Leveling

UBL Bilinear mesh

Your Slicer

Prusa Slicer

Host Software

SD Card (headless)

Don't forget to include

Additional information & file uploads

No response

rondlh commented 1 month ago

This should work fine, it's the basis of all bed leveling. Try this:

  1. Set the Z-offset to 0 (M851 Z0)
  2. Heat the bed to the temperature you commonly use P140 S[your bed temp]
  3. Heat the nozzle to 200 degrees (M104 S200)
  4. Wait until the bed and nozzle have reached the set temperatures
  5. Home the printer (G28) (move the center of the bed if needed)
  6. Move the printer to Z=0 (G0 Z0)
  7. Place a piece of thin paper on the bed, under the nozzle
  8. Babystep until the nozzle starts grabbing the paper
  9. Save your settings (M500)

Now your bed leveling should a roughly correct, some fine adjustments are usually still needed.

GER-HerrS commented 1 month ago

I did it exactly like that (but directly on the controller).

But now I did it again using Octoprint and gcodes.

The result remains the same.

I took a photo and a video.

Pay attention to the Z position after the auto homing is finished. It is 15.4mm first and ends up at 5mm when the homing is done. The printer seems to simple override it at the very end (after the up move after the homing). So when you move to Z position 0 the nozzle is still very high above the bed.

IMG_8326

https://github.com/user-attachments/assets/4b41af18-130d-4c57-b737-a95400631d95

rondlh commented 1 month ago

In German, nice :P

There are various parameters that affect the Z-position after homing, so the Z-position after homing doesn't tell you much. Note that homing doesn't bring your Z-position to 0. Going to a Z=5mm is probably correct.

The display will always lag a bit, that's also not important. The 15.4 you see is probably the probe at it's highest point. What is important is the response of M851 (probe offset), and where the nozzle is when you send the Z position to 0. (G0 Z0). There is nothing going wrong in the video as far as I can see. That's all normal and correct.

GER-HerrS commented 1 month ago

You got me :-D.

Just to make sure we're not talking past each other. It shows 15.4mm while it's moving up the Z axis. So it's moving to 15.4mm. But when it's reached it, it shows the position 5mm. In fact, 15.4mm isn't right at all. When I do the homing, I go down 5mm to get to position 0. Then I go down another 5.4mm until the nozzle scratches the paper. So I'm expecting 10.4mm rather than 15.4mm.

In any case, something is wrong, because with the Z offset set, the nozzle is still too far above the bed after homing to position 0. A print would therefore print the first layer in the air.

GER-HerrS commented 1 month ago

I have now specifically set the language to English and made two new videos. The first video shows the normal auto homing process and that the nozzle is still well above the bed when position 0 has been reached. Mind you: This is already with the Z offset of -5.4mm!

And again I can or must move the Z axis to position -5.4mm to grab the paper on the bed. The printer seems to completely ignore the Z offset and so I can't print at all. I don't know where this phenomenon comes from, but as I said, it has unfortunately not disappeared with the latest versions.

During the homing process, as can be seen in the last video, the Z position is 15.4mm. This is probably also controlled (5.4mm Z offset + 10mm nozzle lift from the bed). But then the position is overwritten with 5mm without the Z axis actually moving to it. So in reality it is at 15.4mm but according to the LCD it is at 5mm. In my opinion there must be something wrong with the homing procedure?

Do you have any other ideas?

IMG_8335

https://github.com/user-attachments/assets/76c73b5b-9436-4b78-99b4-eac9b7a0c4a9

https://github.com/user-attachments/assets/aa5ba29c-8a7f-4adb-971b-0ca22e984b03

Thanks

GER-HerrS commented 1 month ago

No one able to help? Please get me printing again ^^.

GER-HerrS commented 1 month ago

Solution:

define USE_ZMIN_PLUG

has to become: //#define USE_ZMIN_PLUG

as I use no Z end stop except the bl touch.