problem with the Mesh?second print start in the air

lui2004

Ok thanks a lot.

I will test now

Exerqtor

@phaedrux said in problem with the Mesh?second print start in the air:

@exerqtor said in problem with the Mesh?second print start in the air:

@phaedrux said in problem with the Mesh?second print start in the air:

Are you releveling your 2 lead screws again before starting the next print?

Your slicer end gcode turns off the motors, which could cause the two z axis motors to get out of sync.

So you may want to add G32 to your start gcode to run bed.g before the print.

Isn't G32 meant only if one have multible individually driven z-motors? If he drive he's two z-motors in paralell G32 won't do much?

G32 just runs the bed.g macro, which he has setup to do independent lead screw leveling.

Aaah sorry i didn't see that he was running the Z-motors individually!

Wouldn't it be smart to have home Z and X and remove the old bed transform before running the bed.g macro to btw? Like this:

;Start script start
G28 XY                         ; Home X and Y axis
M561                           ; Clear any bed transform that might be in place  
G32                            ; Re-level lead screws
G29 S1                         ; Load and turn on bed height map (mesh)
G1 X0 Y20 Z0.2 F3000           ; Get ready to prime
G92 E0                         ; Reset extrusion distance
G1 X100 E20 F600               ; Prime nozzle
;Start script end

lui2004

@exerqtor said in problem with the Mesh?second print start in the air:

Wouldn't it be smart to have home Z and X and remove the old bed transform before running the bed.g macro to btw? Like this:

what do you mean with

Wouldn't it be smart to have home Z and X and remove the old bed transform before running the bed.g macro to btw?

Phaedrux

@exerqtor he already clears the mesh compensation in bed.g

Exerqtor

@phaedrux said in problem with the Mesh?second print start in the air:

@exerqtor he already clears the mesh compensation in bed.g

Also correct, don't mind me I'll sit this one out

lui2004

I think it works now

Tommorow i will test nore prints

Thanks to all for Help

dc42

I have added some additional notes on using mesh bed compensation at https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation. Main takeaways are:

Immediately before running G29 S0 (or just G29) to probe the bed, you should establish a Z=0 datum using the Z probe. If you home Z using the Z probe the right way, using a G30 command in homez.g/homeall.g, then you will have done that already. Otherwise, before running G29 S0 you should do a single G30 probe at bed centre, or alternatively run delta auto calibration or leadscrew bed levelling.
Before running G29 S1 to load the previously-saved height map, you should also establish a Z=0 datum in exactly the same way.

A height map display that is entirely above or entirely below Z=0 is a signal that you did not establish a Z=0 datum using the Z probe.

I am considering changing the firmware to emit warning messages (and perhaps refuse to run G29) if these conditions are not met, because I suspect this is the main explanation for inconsistencies in the overall Z offset of the height map and changes in the Z=0 position before/after a print.

Exerqtor

@dc42 said in problem with the Mesh?second print start in the air:

I have added some additional notes on using mesh bed compensation at https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation. Main takeaways are:

Immediately before running G29 S0 (or just G29) to probe the bed, you should establish a Z=0 datum using the Z probe. If you home Z using the Z probe the right way, using a G30 command in homez.g/homeall.g, then you will have done that already. Otherwise, before running G29 S0 you should do a single G30 probe at bed centre, or alternatively run delta auto calibration or leadscrew bed levelling.

Before running G29 S1 to load the previously-saved height map, you should also establish a Z=0 datum in exactly the same way.

A height map display that is entirely above or entirely below Z=0 is a signal that you did not establish a Z=0 datum using the Z probe.

I am considering changing the firmware to emit warning messages (and perhaps refuse to run G29) if these conditions are not met, because I suspect this is the main explanation for inconsistencies in the overall Z offset of the height map and changes in the Z=0 position before/after a print.

That sounds like a good idea, or at least make it totally clear in the dozuki that Z homing MUST be done before G29 S0 is issued.

And on that topic, should M561 be issued before Z-homing / G30 in the slicer start script. And then issue G29 or G29 S1 at the very end?

dc42

@exerqtor said in problem with the Mesh?second print start in the air:

And on that topic, should M561 be issued before Z-homing / G30 in the slicer start script. And then issue G29 or G29 S1 at the very end?

That's a wise precaution, although it shouldn't be essential.