Problem: Z-Probe / Auto Bed Compensation / Mesh Grid

kuhnikuehnast

Hi there,
I have a strange problem and am unable to solve it... Hope, you can help me!

I try to adjust the trigger height of my BLTouch like in this tutorial (https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation) But if I run G30 S-1 I get 2 values:

The Head position (under machine Status) tells me 1.76. But the message that pops up says
" M98 P"0:/macros/Test"
Stopped at height 0.756 mm"

If I repeat it, there is always the difference of about 1 mm.

My probe Z-offset is set to 0 to avoid errors.

If I now run Auto Bed Compensation or Mesh Grid Compensation, I get also 2 different results. And additional all probing points seems to be far of the bed in one direction? This is really strange, becaus one of the probing points has to be at least at 0 or not?

This is the config.g of the Z-Probe:

; BLTouch Z-Probe
M307 H3 A-1 C-1 D-1 ; Disable the 3th Heater to free up PWM channel 9 on the Duex board.
M558 P9 H5 F120 T6000 X0 Y0 Z1 ; Set Z probe type/mode 9. H=Dive Height. F=Speed the bed moves
G31 P25 X-27 Y+20 Z0 ; Z probe trigger value, offset in relation to nozzle. And trigger height adjustment
M557 X20:300 Y20:300 S140 ; Define mesh grid

Hope you can help me solve this problem!

dc42

@kuhnikuehnast said in Problem: Z-Probe / Auto Bed Compensation / Mesh Grid:

My probe Z-offset is set to 0 to avoid errors.

That's part or all of the problem.

kuhnikuehnast

Ok, tried it with an offset of 1:
G31 P25 X-27 Y+20 Z1 ;

exact the same problem I really don't know any more what to do???

kuhnikuehnast

Here a screenshot of the differences. I tried with G31 P25 X-27 Y+20 Z3 ;
And exactly the same difference of 1 mm

0_1523458063406_different values.jpg

AdiGital

This post is deleted!

dc42

@kuhnikuehnast said in Problem: Z-Probe / Auto Bed Compensation / Mesh Grid:

Ok, tried it with an offset of 1:
G31 P25 X-27 Y+20 Z1 ;

exact the same problem I really don't know any more what to do???

You need to measure the Z probe trigger height and use that value in the G31 Z parameter. See https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#main.

kuhnikuehnast

@dc42 said in Problem: Z-Probe / Auto Bed Compensation / Mesh Grid:

You need to measure the Z probe trigger height and use that value in the G31 Z parameter. See https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#main.

But I can't measure the Z probe trigger height if I get 2 results when I try to measure it. (one is the popup text and the other is the "head position"). The head position is always 1mm more than the popup message...

AdiGital

Are you sure you're not forgetting step 6 of the guide (zero the current height after adjusting nozzle)?
Then measure G31 and store the reported probe height in config.

kuhnikuehnast

Omg, I think I found the mistake!

In deployprobe.g and retractprobe.g they lookek like this:

;M564 S0 H0 ; don't apply limits
M280 P3 S10 I1 ; deploy probe
M564 S1 H1 ; apply limits again

M564 S0 H0 ; don't apply limits
M280 P3 S90 I1 ; retract probe
M564 S1 H1 ; apply limits again

After deleting the M564 command, it works without problems!!! So is there maybe a bug in the M564 command? With this, always the 1 mm difference, without not!

Phaedrux

What was the intent of the M564 commands?