Hi folks, I wanted to implement grid probing with a bltouch today on a

Hi folks,

I wanted to implement grid probing with a bltouch today on a cartesian printer.
I noticed the following:
My alpha_min is -9, my probe offset in x direction from the nozzle is 41mm.
Therefore, the probe is unable to reach the far left side ob the bed but the carriage is trying to reach it. This causes lost steps and a false positioning.

Is there a way to manually set the probing points and / or range?

This is my leveling strategy section:
leveling-strategy.rectangular-grid.enable true
leveling-strategy.rectangular-grid.x_size 200
leveling-strategy.rectangular-grid.y_size 200
leveling-strategy.rectangular-grid.size 7

leveling-strategy.rectangular-grid.tolerance 0.03
leveling-strategy.rectangular-grid.do_home false
leveling-strategy.rectangular-grid.probe_offsets 41,20,0
leveling-strategy.rectangular-grid.save true
leveling-strategy.rectangular-grid.initial_height 10
leveling-strategy.rectangular-grid.human_readable true
mm_per_line_segment 1

Thanks in advance

@Arthur_Wolf , can you help out here? Any ideas?

I had the same issue and in about 8 hours when I am back near my cartesian printer I dig out the config and post the relevant section; I recall that in my case, it homes to X-MIN and I had to reduce the X_size to be the distance from the probe to the opposite side, i.e. reduce it by the Z-Probe X offset, so it was 200mm - 80mm which if I recall meant:
leveling-strategy.rectangular-grid.x_size 200
leveling-strategy.rectangular-grid.x_size 120
And the same is true for he Y Axis

@Douglas_Pearless I also thought about this. But wouldnt this result in a shifted grid?

I have not read the source code in this area for quite a while so I cannot remember if it does compensate for the offset:-) but it works for me :slight_smile:

Maybe this makes it a bit clearer missing/deleted image from Google+

OK, then you will need to reduce the:
leveling-strategy.rectangular-grid.x_size 200
leveling-strategy.rectangular-grid.y_size 200
until it fits over the bed :slight_smile:

@Douglas_Pearless And also the alpha_min and / or probe offset, right? If not, the probe still tries to reach the left side, but can’t and slams into the x endstop

Here is my config for a 200x200 bed (Wanhao i3) with a BL Touch offset by X = -34 and Y= -50 from the nozzle:

leveling-strategy.rectangular-grid.enable true # The strategy must be enabled in the config, as well as the zprobe module.
leveling-strategy.rectangular-grid.x_size 125 # size of bed in the X axis
leveling-strategy.rectangular-grid.y_size 125 # size of bed in the Y axis
leveling-strategy.rectangular-grid.size 9 . # The size of the grid, for example, 7 causes a 7x7 grid with 49 points.
# Must be an odd number.
leveling-strategy.rectangular-grid.do_home true
leveling-strategy.rectangular-grid.probe_offsets -34,-50,1.8 # Optional probe offsets from the nozzle or tool head
leveling-strategy.rectangular-grid.save true # 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.dampening_start 0.5 # compensation decrease point (optional)
leveling-strategy.rectangular-grid.height_limit 1 # no compensation to apply after this point (optional)
mm_per_line_segment 1 # necessary for cartesians using rectangular-grid

Thanks dude

Has the issue of having the Z probe sensor offset from the printing nozzle (or cutter/laser head) ever been fixed?. I have been struggling with a DIY CoreXY and my new Smoothie board with smoothieware for a week trying to get the thing to do a grid compensation (G32) without having the head crash when the probe moves off the build platform when starting the second row of the z probe testing. Reducing the build size is not an acceptable solution for this hardware configuration. This condition is easy to adress on a Marlin based system by specifying the z-probe’s offset from the nozzle. That does not seem to do anything in the smoothieware except for the first row, after that head crash when the probe if off of the bed.

@Elwyn_Lyles_Cranford, are you saying that leveling-strategy.rectangular-grid.probe_offsets isn’t honored?