Auto level - Prints about 10mm above bed.

Stormblade

Hi,

I've been struggling to get auto-leveling to work.

I'm using a BLTouch sensor.

The sensor is working fine and I can do a G29, and a G32 S2 with no problems at all.

However, when I start printing, it tries to print a few centimetres above the bed.

This is my start code...

G21 ;metric values

G90 ;absolute positioning

M107 ;start with the fan off

G28 X0 Y0 ;move X/Y to min endstops

G28 Z0 ;move Z to min endstops

G32 S2 ;

G28 X0 Y0 ;move X/Y to min endstops

T0 ;

G1 Z15.0 F{travel_speed} ;move the platform down 15mm

G92 E0 ;zero the extruded length

G1 F200 E3 ;extrude 3mm of feed stock

G92 E0 ;zero the extruded length again

G1 F{travel_speed}

;Put printing message on LCD screen

M117 Printing...

Any idea what is going wrong?

Thanks,

Simon.

Stormblade

Some more information.

G28

Homes X, then Y, then Z to ZMin switch.

G32

Does Bed probing correctly.

G1 Z0

Moves the nozzle about 32mm above the bed, LCD shows Z0.

The same thing happens using G29 instead of G32.

Z Probe height is set to 4.1mm in eeprom (measured).

azurha

I have exactly the same problem.

MartinH

#define ENDSTOP_Z_BACK_ON_HOME 0

make sure this is st to 0

azurha

it was set on 20 !

Now i set at 0, but i still the same problem, the nozzle up for _10mm above the bed :/

Repetier

Is z min switch also the z probe switch?

Also check if bed caoting is set 0.

Are you using dev version?

azurha

Hi o/

I use the version 0.92.9 and i have #define UI_BED_COATING 1

What is this parameter ?

Repetier

If you have z max leveling or inductive z probe you can adjust height after homing to accomidate to different thick coatings e.g. Kapton or blue tape. Current thinkness assumed is visible in eeprom as bed coating thinkness.

Stormblade

I found my problem, the Z Probe offset was set in steps not mm, I think I read that it uses the same rules as the multiple nozzle offsets (which are done in steps), and the Config file I have doesn't specify units.

Fixing that, and then using the right entry to modify the Z Probe height sorted my problem out.

Thanks.