Another mesh bed leveling thread...

Blacksheep99

@zapta said in Another mesh bed leveling thread...:

@wingtip said in Another mesh bed leveling thread...:

Is this a good option to do both as i have independant z lead screws and the bl touch?

I think so. The first will level mechanically the Z mounting points, and the second will take care of any leveling error or surface non flatness.

Also, you want to re-home z after the technical leveling since it can shift the 0 point and you want to do the entire process with bed heated to print temperature. Or at least this is what my printer does.

This is my approach also. One thing I do when running the Z level is to disable the mesh if there's one. I think this is the logical thing to do.

wingtip

@fcwilt
https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation

fcwilt

@wingtip said in Another mesh bed leveling thread...:

@fcwilt
https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation

Thanks.

I just wanted to verify the the docs were not using the term "mesh bed leveling" which is what you used in the title of your post.

Bed Leveling (manual or automatic) and Mesh Bed Compensation are two very different things.

Mixing the terms can lead to confusion.

Frederick

wingtip

@fcwilt ummmm so then i cant use both z lead screw leveling and mesh leveling then after all... this is all new stuff to me as this is my first duet, first bl touch, and first time with reprap having been used to marlin with my ft5...

Does my configs look ok and what should my next step be?

fcwilt

@wingtip

Yes you can use both Bed Leveling (either Manual or Automatic) and Mesh Bed Compensation

Please note to avoid confusion the term is Mesh Bed Compensation not Mesh Bed Leveling

Frederick

zapta

Mesh compensation is virtual leveling and flattening.

The duet could use mesh information for a more accurate mechanical leveling but I don't think it's supported.

I think we use different words but talk about same concepts.

Phaedrux

@wingtip said in Another mesh bed leveling thread...:

  G1 H1 Z-400 F400  ; move quickly to z axis endstops and stop there (first pass)                                                                                                                                                                                                                                                                                                                                          G1 H2 Z5 F1800       ; go back a few mm                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      G1 H1 Z-10 F360  ; move slowly to z axis endstops once more (second pass)

Your homeall still has a endstop homing pass for Z, but you don't have an endstop for Z defined in config.g so that will generate an error. You can remove those lines and just use the probe for homing Z. Or if you do have a Z endstop, you'd need to define that endstop in config.g

@wingtip said in Another mesh bed leveling thread...:

G1 H2 X5 Y5 F1800 ; go back a few mm

The H2 switch should only be used for the Z axis to lift it for clearance before it's been homed. Don't use H2 on the X Y back off moves. It could potentially mask an endstop failure.

@wingtip said in Another mesh bed leveling thread...:

In reading the dozuki it mentions being able to do both lead screw leveling and mesh leveling. Is this a good option to do both as i have independant z lead screws and the bl touch?

Yes, it's a good idea if you have 2 Z motors raising the X gantry. Overtime the two Z motors can get out of sync from power cycles causing them to jump in opposite directions.

There's an example for 2 motors here: https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

Here's a sequence of gcode events that might help clear up how you want things to happen.

G28 should home XY and Z with the probe in the center of the bed with G30.

G32 (bed.g) should probe (g30) at both ends of the X axis for tilt correction and then home Z again in the center of the bed (g30).

G29 would then be used to create a heightmap of the surface of the bed and would compensate for the shape of the bed by lifting and lowering Z to keep the distance between nozzle and bed the same across the entire surface.

For spacing between points it's usually best if you can max out the number of points and then just load that saved detailed map before each print rather than redoing the mesh each time.

You should do a detailed probing at least once so you can get a good idea of what the surface of the bed looks like. If it's exceedingly flat you can get away with a lower density.

fcwilt

@zapta said in Another mesh bed leveling thread...:

Mesh compensation is virtual leveling and flattening.

While it can compensate for a out of level bed that is not the best approach to dealing with a out of level bed.

The documentation refers to Mesh Bed Compensation not Mesh Bed Leveling.

Using another term can lead to confusion.

Frederick

zapta

@blacksheep99 said in Another mesh bed leveling thread...:

when running the Z level is to disable the mesh if there's one

Is the independent Z leveling affected by the mesh data, if loaded? That is, different mesh data will result in different Z leveling?

Phaedrux

@zapta I don't think so, since the tilt correction would be using G30 commands to find Z0, but it is recommended to cancel any transforms with M561 regardless.

wingtip

Im really trying to get a grasp on all this but there are so many options and functions you can do and its overwhelming.
I did have endstops on the dual z lead screws but was told i couldnt use those if i was installing the bl touch so i removed those quite a bit ago. All that i have for z is the bltouch right now.

Based on padreux suggestion i removed those lines from the homeall... the new homeall is as follows:

; homeall.g
; called to home all axes

;

; generated by RepRapFirmware Configuration Tool v2.1.1 on Sun Nov 03 2019 09:32:23 GMT-0500 (Eastern Standard Time)


G91                     ; relative positioning

G1 H2 Z5 F6000          ; lift Z relative to current position


G1 H1 X-805 Y-505 F800  ; move quickly to X and Y axis endstops and stop there (first pass)

G91
G1 H2 X5 Y5 F1800       ; go back a few mm

G1 H1 X-10 Y-10 F360  ; move slowly to X and Y axis endstops once more (second pass)

G92 X0 Y0 Z0
G90                     ; absolute positioning

G1 H2 X15 Y15 F6000     ; go to first bed probe point and home Z

G30                     ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing

G91                    ; relative positioning

G1 H2 Z5 F100          ; lift Z relative to current position

G90                    ; absolute positioning

as for the H1 and H2, those were what was told to me by others in another thread on these forums. If a line needs edited please identify (and hopefully explain why so im learning, albeit slowly lol)

Home z is still

G91 ; relative positioning
G1 H2 Z5 F2000 ; lift z for clearance
G90 ; absolute positioning
G1 X320 Y220 F4000 ; moves probe to approximate bed center. 
G30 ; probe the bed
G1 X0 Y0 Z5 F4000 ; return to origin position

Im guessing i need another macro or two , to execute bed probing and then auto leveling?? And still wondering what spacing you guys suggest on the probing. Currently i have it set to 20mm. On a bed thats nearly 800x500 that could be a lot of probes??

fcwilt

@wingtip said in Another mesh bed leveling thread...:

I did have endstops on the dual z lead screws but was told i couldnt use those if i was installing the bl touch

Not true.

You can use typical endstop devices for homing Z even with multiple steppers if you have a endstop device for each stepper.

I have 3 steppers and 3 associated endstop devices - it homes just fine.

quick video of Z Homing 3 Steppers

When using endstops for homing you then use the Z probe (BLTouch in your case) for:

Auto Bed Leveling (G32)
Creating the height map(s) for Mesh Bed Compensation (G29)
Setting the Z=0 Datum (G30)

Frederick

Phaedrux

Yes it can all be a bit overwhelming.

Here's what I would use for homeall.

; homeall.g
G91                     ; relative positioning
G1 H2 Z5 F6000          ; lift Z relative to current position
G1 H1 X-805 Y-505 F800  ; move quickly to X and Y axis endstops and stop there (first pass)
G1 X5 Y5 F1800       ; go back a few mm
G1 H1 X-10 Y-10 F360  ; move slowly to X and Y axis endstops once more (second pass)
G90                     ; absolute positioning
G1 X320 Y220 F4000 ; moves probe to approximate bed center.
G30                     ; home Z by probing the bed
G1 X0 Y0 Z5 F4000 ; return to origin position

Removed the H2 from the XY moves.
Removed the G92 to force a position. The position will be determined by the M208 minima value set in config.g
Changed the probe position to match your homez.

In bed.g you need to specify two points close to the lead screws to probe and a command in config.g to tell the firmware where those lead screws are located.

Example here shows what you need.

https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_Example_for_2_motors

Final bed.g would look something like this (with your actual positions)

; bed.g
M561 ; clear any bed transforms
G28 ; home all
G30 P0 X20 Y100 Z-99999 ; probe near a leadscrew, half way along Y axis
G30 P1 X180 Y100 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors
G1 X320 Y220 F4000 ; moves probe to approximate bed center. 
G30 ; probe the bed
G29 ; create a mesh grid
G1 X0 Y0 Z5 F4000 ; return to origin position

@wingtip said in Another mesh bed leveling thread...:

And still wondering what spacing you guys suggest on the probing. Currently i have it set to 20mm. On a bed thats nearly 800x500 that could be a lot of probes??

You're limited to 441 points, so if you set a very low spacing in your m557 command and send it in the gcode console (like 1mm) it will tell you what your minimum spacing would be to stay within the limit.

It's also possible to use number of points to probe and it will figure out the spacing to get that number of points.

M557 X15:630 Y15:415 P10 for example will probe a 10x10 grid.