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Mecanical Z endstop and auto bed levelling

Posted by B2V 
Mecanical Z endstop and auto bed levelling
November 22, 2017 05:41PM

I have an capacitive sensor installed on my PRUSA I3 but I noticed that Z positionning is not quite precise, I need three or four departure before it find the good level (perhaps warming), while optical endstop always give a good start.

if correct Z positionning, with auto levelling, is not easy to find when Ok the adherence is improved.

Can anyboby tell me how to configure Marlin in order to:
- Use my capacitive sensor to memorise auto levelling data
- use levelling matrix to correct surface defaults and have a very good adherence
- keep initial optical or mechanical Z levelling which provide very precise positionning.

thanks for answers
Re: Mecanical Z endstop and auto bed levelling
November 22, 2017 05:53PM
I do not know what firmware you are using, but will show you how I save my auto-bed leveling data in Marlin 1.1.X

Before Bed Leveling I use M502 to Restore Firmware Factory Reset - defaults.

After Auto Bed Leveling I use M500 to Save All EEProm settings

In Cura or whatever your default Slicer I simply restore Bed Leveling Data after Last Startup G-code
M420 S1

My Sample Startup G-Code
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
;Put printing message on LCD screen
M117 My Print...
G28 X0 Y0
G1 E4.0 ;prime extruder
G92 E0 ;reset extruder length
M420 S1 ; Bed Leveling On

M420 Commands below
M420: Enable/Disable Bed Leveling and/or set the Z fade height.
S[bool] Turns leveling on or off
Z[height] Sets the Z fade height (0 or none to disable)
V[bool] Verbose - Print the leveling grid
Re: Mecanical Z endstop and auto bed levelling
November 22, 2017 06:15PM
I use Marlin (for megatronics v3.0) and slic3r optimized for PRUSA with repetier.

I'm going to test M420.thumbs up

Thanks for your answer
Re: Mecanical Z endstop and auto bed levelling
November 25, 2017 05:19PM
.... Well

M420 S1 didn't seem to work the way I want...

I saw that it need to have MESH_BED_LEVELING set

But to archive Auto bed levelling, I need to keep AUTO_BED_LEVELING_FEATURE set

unfortunatly they can't be set together.

There's no M420 level correction with only MESH_BED_LEVELING or AUTO_BED_LEVELING_FEATURE

Edited 1 time(s). Last edit at 11/25/2017 05:26PM by B2V.
Re: Mecanical Z endstop and auto bed levelling
November 25, 2017 06:35PM
This is true, the M420 Z features do not work. I was happy just to save the bed leveling. An maybe one day the others will be added as well.

I started saving the Bed leveling data while using Linear bed leveling and now have changed to bi-linear bed leveling and sill saving the bed leveling data.
However I have to use the Menu "Store settings" or M500 from pronterface in Cura 15.04.6.

Video is a little jerky

Edited 2 time(s). Last edit at 11/25/2017 07:08PM by Roberts_Clif.
Re: Mecanical Z endstop and auto bed levelling
November 26, 2017 11:02AM
Thanks for your video... Beautiful printer winking smiley, mine is build of pieces took here and there...

Anyway I finally succeed smileys with beer

First, I add a switch which can select either my optical endstop or my capacitive sensor.

I upgrade marlin to version 1.1.6 and enables AUTO_BED_LEVELING_UBL.

then I proccess this:

Switch to Capacitif sensor

M502          ; Reset settings to configuration defaults...
M500          ; Save to EEPROM
M501          ; Read back in the saved EEPROM.  

G28            ; Home XYZ.
G29 P1       ; Do automated probing of the bed.

G29 S1       ; Save UBL mesh points to EEPROM.
G29 A         ; Activate the UBL System.
M500          ; Save current setup.

Switch to optical end stop

after that I simply add g-code for all prints

G1 Z5 F4000; just to prevent any hurt
G28            ; Home XYZ.

Thats all I can now print using precise optical endstop and level correcting for best adherence
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