Trouble with V3 Z offset using old and new firmware

[timskloss]

I am having trouble calibrating the bed on my V3. I have tried both the 'old' V3 probing gcode file from SeeMe and the new development firmware. In both cases I am getting a Z0 that is about 0.15 mm above the bed. This measurement is consistent at +/- 100 mm in x/y so the bed is pretty flat. I always clean the nozzle and run the calibration with cold bed and extruder.

I discovered the offset after a lot of frustrating work trying to get ABS to stick to the bed--the nozzle was just to high.

Currently I am using a Z offset of -0.07 mm and it seems to give a decent first layer, but I want to fix this problem in the printer so Z0 is really at 0.00 mm. Here are the EEPROM settings after running the new development firmware:

Code: Select all

<-EPR:2 79 900000 Max. inactive time [ms,0=off]
<-EPR:2 83 600000 Stop stepper after inactivity [ms,0=off]
<-EPR:3 11 80.0000 Steps per mm
<-EPR:3 23 250.000 Max. feedrate [mm/s]
<-EPR:3 35 80.000 Homing feedrate [mm/s]
<-EPR:3 39 32.000 Max. jerk [mm/s]
<-EPR:3 133 0.000 X home pos [mm]
<-EPR:3 137 0.000 Y home pos [mm]
<-EPR:3 141 0.000 Z home pos [mm]
<-EPR:3 145 250.000 X max length [mm]
<-EPR:3 149 250.000 Y max length [mm]
<-EPR:3 153 402.388 Z max length [mm]
<-EPR:3 59 1850.000 Acceleration [mm/s^2]
<-EPR:3 71 3000.000 Travel acceleration [mm/s^2]
<-EPR:3 881 291.060 Diagonal rod length [mm]
<-EPR:3 885 143.901 Horizontal rod radius at 0,0 [mm]
<-EPR:3 925 200.000 Max printable radius [mm]
<-EPR:1 891 80 Segments/s for travel
<-EPR:1 889 200 Segments/s for printing
<-EPR:1 893 65 Tower X endstop offset [steps]
<-EPR:1 895 0 Tower Y endstop offset [steps]
<-EPR:1 897 87 Tower Z endstop offset [steps]
<-EPR:3 901 210.000 Alpha A(210):
<-EPR:3 905 330.000 Alpha B(330):
<-EPR:3 909 90.000 Alpha C(90):
<-EPR:3 913 0.000 Delta Radius A(0):
<-EPR:3 917 0.000 Delta Radius B(0):
<-EPR:3 921 0.000 Delta Radius C(0):
<-EPR:3 933 0.000 Corr. diagonal A [mm]
<-EPR:3 937 0.000 Corr. diagonal B [mm]
<-EPR:3 941 0.000 Corr. diagonal C [mm]
<-EPR:3 808 -0.200 Z-probe height [mm]
<-EPR:3 929 20.000 Max. z-probe - bed dist. [mm]
<-EPR:3 812 90.000 Z-probe speed [mm/s]
<-EPR:3 840 50.000 Z-probe x-y-speed [mm/s]
<-EPR:3 800 0.000 Z-probe offset x [mm]
<-EPR:3 804 0.000 Z-probe offset y [mm]
<-EPR:3 816 -123.565 Z-probe X1
<-EPR:3 820 -71.340 Z-probe Y1
<-EPR:3 824 123.565 Z-probe X2
<-EPR:3 828 -71.340 Z-probe Y2
<-EPR:3 832 0.000 Z-probe X3
<-EPR:3 836 142.680 Z-probe Y3
<-EPR:0 880 1 Autolevel active (1/0)

What is the 'correct' way to adjust so I don't have to worry about it when slicing?

Thanks in advance!

[mhackney]

Tim, there is a configuration parameter in EEPROM called something like Z-Probe Height - you can see it in your post above. By default that is set to -0.20mm but I assert that it really should be tuned for each printer. I posted instructions in my V3 build thread 2 weeks ago or so.

This offset is ADDED to the measured Z height to compensate for systematic probe trigger offsets like switch actuation, bed movement, etc. You should be able to tweak as per my thread and be dead on.

Also, a word for folks reading this NEVER compensate for Z=0 in your slicer. That is a recipe for frustration and failure. Adjust your machine and calibrate Z height. Read the post in my signature for more information on how to do this. It is the only way to get consistent first layer thickness and adhesion.

[timskloss]

Mike, you are a BIG help. I made good progress this morning. I should have read your V3 build thread all the way through a week ago.

-installed EEPROM reader into Octoprint
-changed probing locations to match your new ones
-optimized the end stop screw positions
-ran back to back calibrations using the new development Auto Calibration firmware

Code: Select all

X end stop		-1		1		0		1
Y end stop		-1		0		0		0
Z end stop		 1		3		2		2
Horz Radius		143.963	143.956	143.956	143.949
Z Max Len			402.250	402.231	402.244	402.238

The repeatability looks good I think.

[timskloss]

After the calibration above I checked my nozzle-bed gap at Z0 and still found about 0.16mm gap. I changed the Z probe height in the EEPROM from the original -0.20 mm to -0.04 mm and after a new calibration run the height is within 0.01 mm.

I'm a happy camper now and look forward to taking out the Z offset from the printer settings in my slicers.

Thanks again for the help!

[mhackney]

Yup, that looks like consistent calibration results and your change to Z probe height should work great now.

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