Bed Level compensation not working correctly

Argo

Just curious but what’s your probe offset to the nozzle?

StevePS3

@argo
G31 P500 X0 Y0 Z3.75

Argo

Oh you were posting the config at the same time I asked.
Is the nozzle your probe, I mean are you using one of those push the nozzle to trigger the probe units?

StevePS3

@argo
I am using a BL Touch. It is approximately 5cm behind the nozzle.

StevePS3

I did read somewhere, and this may be a complete red herring, that because parts of the bed are below zero then something needs to be done to the config to allow the head to move to a Z position < 0.

As I say it may be a red herring. It was just something I read whilst attempting to search for a solution.

I also think that I need to get my 6mm aluminium bed levelled. I'll have to find a machine shop that can skim it for me.

fcwilt

@steveps3 said in Bed Level compensation not working correctly:

M561 ; clear any bed transform
G28 ; home
G30 P0 Y00 X150 Z-99999
G30 P0 Y00 X150 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 Y275 X150 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

M29 S2

The first thing you need to do is edit, in config.g, the G31 X and Y parameter values to reflect the actual offset of the probe from the nozzle. You mentioned "approximately 5cm) which is a start.

In the bed.g file you have G30 P0 Y00 X150 Z-9999 twice - it may not hurt but but it is redundant.

You also have a M29 S2 - what is the reason for that?

In your "start" gcode you have G29 S1 which loads the existing heightmap file. I don't see where you create the height map with a G29 S0.

StevePS3

@fcwilt

I've measured the difference now and it is 3cm behind the nozzle. So I've updated the config.h

G31 P500 X0 Y30 Z3.75

I've also updated the bed.h to remove one of the
G30 P0 Y00 X150 Z-99999
and also the M29 S2

I think I was clearing the height map just so that start with a clean slate.

The G29 S1 is performed as part of my start gcode.

G21 ; set units to millimeters
G32
G29 S1
M104 S[first_layer_temperature] ; set extruder temp

I'll give those changes a try.

StevePS3

This post is deleted!

StevePS3

Something strange has happened. I don't know why but the height map is now being created with the first point being the bottom right. Up until now the first probe point has been bottom left. Other than that not a lot has changed. The compensation is still nowhere near what it should be.

fcwilt

@steveps3 said in Bed Level compensation not working correctly:

Something strange has happened. I don't know why but the height map is now being created with the first point being the bottom right. Up until now the first probe point has been bottom left. Other than that not a lot has changed. The compensation is still nowhere near what it should be.

When you specified the X and Y offsets of the probe you changed where the firmware had to move the probe to get to the specified points.

It likely cannot get to one (or more) of the points being to close to the min/max limits on the X and/or Y axis.

fcwilt

@steveps3 said in Bed Level compensation not working correctly:

The G29 S1 is performed as part of my start gcode.

My bad - I have corrected my post.

Where do you create the height map (G29 or G29 S0)?

Thanks.

StevePS3

@fcwilt
Maybe. The head did go crashing into the frame of the printer until I changed the G30 positions.

StevePS3

@fcwilt
I think it’s a G29. It is whatever the command is under the compensate and calibrate button.

fcwilt

@steveps3 said in Bed Level compensation not working correctly:

@fcwilt
I think it’s a G29. It is whatever the command is under the compensate and calibrate button.

Got it.

I've seen the button but have never used it - I have my own macros for creating height maps.

Thanks.