save bed.g using multiple independent Z motors

tom33

Hi,

I have a question about saving the bed leveling when you use multiple Z motors.
I have 3 Z motors for my build plate.

bed.g : I'm using something like this

G30 P0 X20 Y20 Z-99999 ; probe near a leadscrew
G30 P1 X100 Y180 Z-99999 ; probe near a leadscrew
G30 P2 X180 Y20 Z-99999 S3 ; probe near a leadscrew and calibrate 3 motors

and
config.g

M584 X0 Y1 Z2:5:6 E4; three Z motors connected to driver 2 (front left), driver 5 (rear middle) and driver 6 (front right)
M671 X-15:100:215 Y-10:190:-10 S0.5 ; position of leadscrew/bed pivot point at front left, rear middle and front right
M208 X-5:205 Y0:200 ; X carriage moves from -5 to 205, Y bed goes from 0 to 200

The question is, there is a way to save the offset calculate by the board and apply the same offset after a G28 for exemple ?

It's to avoid to run the G32 at all the startup of the machine.

I don't want to use G29 to have no Z compensation during the print

Thanks !

fcwilt

@tom33

The short answer is no, you cannot save the results of auto bed leveling and apply them again.

The long answer is you don't want to do that.

Think about the time it takes to do the actual print and the time to do the auto bed leveling process (G32).

Things change over time and with environmental conditions.

I don't do anything at the startup of the machine that involves movement.

I manually home the printer once it is up and running.

I manually create the height map (when needed) after heating the bed and allowing it to stabilize.

At the start of each print I auto level the bed, set the Z=0 Datum, load the height map and then the actual printing can begin.

Frederick

A Former User

This post is deleted!

tom33

@Herve_Smith Thanks for the macro, but with this you need to run tour G32 at each startup of the machine

fcwilt

@Herve_Smith

What is the G30 Z-99999?

I cannot find anything in the documentation as to what that is.

Frederick

gloomyandy

@fcwilt From the G30 documentation:

If a "normal" Z parameter is given instead of -9999 or lower, then the bed is not probed, but instead that value is used as if the Z probe had triggered at that height.

Note that in this case -99999 is lower than -9999

fcwilt

@gloomyandy

Yes but that reference appears in the section dealing with using a P parameter with G30.

And all of the examples showing Z-9999 include a P parameter.

Since he is using -99999, if it applies in the absence of a P parameter it is just going to be the same as G30 by itself.

Frederick

A Former User

This post is deleted!