Bed probing

jerolee

Hi, i have a issue with the bed mesh after i set the Z height offset in config.
i run the G32 before Bed mesh probing.
When the value is Z0.0 probe offset in config, the bed mesh probing works fine. when i set the offset (aquired with the tuning procedure) in my case Z0.85 (a positive number with use of BLTouch?)
I get the warning "to large Z offset" in the console after Bed mesh probing and shows the projection of the bed in the height map about this offset under the grid.

Im using rrf 3.3

"bed.g in config file"

M561 ; clear any bed transform
G29 S2 ; clear bed height map
G28 ; home all axis
G30 P0 X70 Y10 Z-99999 ; probe near a leadscrew
G30 P1 X70 Y290 Z-99999 ; probe near a leadscrew
G30 P2 X580 Y290 Z-99999 ; probe near a leadscrew
G30 P3 X580 Y10 Z-99999 S4 ; probe near a leadscrew and calibrate 4 motors

"z probe macro"
G28 ; home all axis
G29 S0 ; Probes the bed, saves the height map and activate bed compensation
G1 X300 Y150 F3000 ; go to center bed

"config.g"

; Z-Probe
M950 S0 C"duex.pwm1" ; create servo pin 0 for BLTouch
M558 P9 C"^zprobe.in" H5 F120 T4000 ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X36 Y9 Z0.85 ; set Z probe trigger value, offset and trigger height
M557 X65:585 Y20:280 S130 ; define mesh grid

; Pressure Advance
M572 D0 S0.05 ; pressure advance typical for direct drive extruder starts at 0.025

; Taper Height - i disabled taper height just to exclude it for solving problem
;M376 H5 ; tapering off the bed mesh compensation in mm

fcwilt

@jerolee

A few comments regards the current approach to bed leveling (G32) and mesh bed compensation (G29) :

G32 runs bed.g which would contain the commands to level the bed, either manually or automatically.
G29 runs mesh.g which would contain the commands to create the height map needed for mesh bed compensation.

The DWC has a pull-down menu with items for G32 and G29. It is implemented expecting that G32 does bed leveling and G29 does height map creation.

Now on to your issue.

There is a process referred to as Setting the Z=0 Datum. This is done with a single G30 command preceded by a G1 command to move the probe to your XY reference point, which is simply the point on the bed where you set the Z=0 datum.

Some folks used one of the grid points that make up the height map as the XY reference point. Others, like myself, use the center of the bed.

Regardless of what point you use it is imperative that you set the Z=0 Datum at certain times:

before creating the height map using G29 S0
before loading the height map using G29 S1
after leveling the bed with G32 (if you do use bed leveling)

When you get the message you are getting is usually because you didn't set the Z=0 datum before creating/loading the height map.

Frederick

jerolee

@fcwilt
Aha, i copied a homez.g from cris on youtube. this doesnt contain a G30 command. That probably is the culprit.
I changed this and gonna run a test.

Thanks mate

Fixed, the absence of a G30 in homez.g was the problem.

jerolee

@fcwilt
Im running my very first testprint on this homemade printer now, is awesome feeling
thanks for the fast reply!

fcwilt

@jerolee said in Bed probing:

@fcwilt
Im running my very first testprint on this homemade printer now, is awesome feeling
thanks for the fast reply!

Glad I was able to help.

Frederick