howto grid leveling when probe can't be brought to 0,0

Controllers Smoothie
1

Hello

I use:
Cetus printer with a cpu that runs (successfully) smoothieware. The size is 180x180x180. I use a 3D Touch Auto Leveling sensor.
When i try to use 3point leveling everything works fine and without problem.
But because my bed seems to be a bit more curvy and because of design its not possible to adjust it better i like to use grid leveling.
No my problem.

If i configure this:
—-
leveling-strategy.rectangular-grid.enable true # The strategy must be enabled in the config, as well as the zprobe module.
leveling-strategy.rectangular-grid.initial_height 10 # move to Z10 before first probe.
leveling-strategy.rectangular-grid.do_home false
leveling-strategy.rectangular-grid.x_size 180 # size of bed in the X axis
leveling-strategy.rectangular-grid.y_size 180 # size of bed in the Y axis
leveling-strategy.rectangular-grid.size 5 # The size of the grid, for example, 7 causes a 7x7 grid with 49 points. must be an odd number
leveling-strategy.rectangular-grid.probe_offsets 38,0,0 # Optional probe offsets from the nozzle or tool head
leveling-strategy.rectangular-grid.save false # If the saved grid is to be loaded on boot then this must be set to true
leveling-strategy.rectangular-grid.initial_height 10 # will move to Z10 before the first probe
leveling-strategy.rectangular-grid.human_readable true
mm_per_line_segment 1 # necessary for cartesians using rectangular-grid

The probe tries to go to -38 (which is the real offset of the probe) to test 0.0. But that isn’t possible because my motors can only go to 0.0 - There is no “free room” to move more in any direction. That means with my shown config it pushed against the end stop and that doesn’t sound nice. But it can’t move the probe to X0

I tried to find a workaround, but then i have the problem, that the system thinks that x0 is somewhere else.

What can i do, to use grid leveling even with that printer where i can “go” from 0.0 to 180.180 only? Is that possible?

I tried (what is nonsense because i loose bed space and the system thinks only for leveling that x0 is somewhere else:

leveling-strategy.rectangular-grid.enable true # The strategy must be enabled in the config, as well as the zprobe module.
leveling-strategy.rectangular-grid.initial_height 10 # move to Z10 before first probe.
leveling-strategy.rectangular-grid.do_home false
leveling-strategy.rectangular-grid.x_size 140 # size of bed in the X axis
leveling-strategy.rectangular-grid.y_size 180 # size of bed in the Y axis
leveling-strategy.rectangular-grid.size 5 # The size of the grid, for example, 7 causes a 7x7 grid with 49 points. must be an odd number
leveling-strategy.rectangular-grid.probe_offsets 0,0,0 # Optional probe offsets from the nozzle or tool head
leveling-strategy.rectangular-grid.save false # If the saved grid is to be loaded on boot then this must be set to true
leveling-strategy.rectangular-grid.initial_height 10 # will move to Z10 before the first probe
leveling-strategy.rectangular-grid.human_readable true
mm_per_line_segment 1 # necessary for cartesians using rectangular-grid

and with the milling commands (i think that is wrong too because i understand that the system again think that X0 is somewhere else only for leveling:
#3D TouchGrid (G31 command only, G31X35Y0 A145B180)
leveling-strategy.rectangular-grid.enable true # The strategy must be enabled in the config, as well as the zprobe module.
leveling-strategy.rectangular-grid.initial_height 10 # move to Z10 before first probe.
leveling-strategy.rectangular-grid.do_home false
leveling-strategy.rectangular-grid.x_size 180 # size of bed in the X axis
leveling-strategy.rectangular-grid.y_size 180 # size of bed in the Y axis
leveling-strategy.rectangular-grid.size 5 # The size of the grid, for example, 7 causes a 7x7 grid with 49 points. must be an odd number
leveling-strategy.rectangular-grid.probe_offsets 38,0,0 # Optional probe offsets from the nozzle or tool head
leveling-strategy.rectangular-grid.save false # If the saved grid is to be loaded on boot then this must be set to true
leveling-strategy.rectangular-grid.initial_height 10 # will move to Z10 before the first probe
leveling-strategy.rectangular-grid.human_readable true
mm_per_line_segment 1 # necessary for cartesians using rectangular-grid
leveling-strategy.rectangular-grid.only_by_two_corners true # for G31 command

Maybe i understand something wrong in the wiki.
Can someone help and understand my problem? (sorry for slightly bad english - it is my 2nd language only)

Thanks in advance
G

Imported from wikidot

2

Your problem seems to by the physical makeup of your machine. if you have offset as -38, so the probe touches the bed are true 0, the head has to have room to go to -38. if the head wont move that far then all you can do is to reposition the probe closer to 0.
If you can do that, all you can do is use a reduced build size of 142 x 180
the way your new build starts at 38mm mark, and doing the probe will start at 0, but is really at 38mm on your bed.

3

With Marlin and Unified Bed Leveling, this is possible though.
Just need to tell the offsets of bed and probe and Marlin calculates the points the probe couldn’t reach by using the nearest ones.
Really disappointing that Smoothieware doesn’t have many of the marlin features… but hey, it’s free and it’s a work in progress. :wink:

4

There isn’t a Smoothie limitation here, this is just a physical limitation of the machine. Smoothie will level no matter what you do, this conversation was just about the fact that the probe is offset …