Question: BL Touch Probe Offset & Mesh Bed Leveling

wieman01

Hello,

I hope this is an easy one... I am using a BL-Touch as proximity sensor and have configured a XY-Offset as it sits in front of the nozzle:

G31 P25 X0 Y-36 Z1.100

These are the axis limits:

M208 X0:480 Y0:350 Z0:260 S1

Z probe has been calibrated using the center point of my print bed (X240, Y175).

This is how I invoke mesh bed leveling:

G32
M557 X0:480 Y0:350 P5:4 		; probing points for mesh bed compensation
G29 S2					; clear height map
G29 S0 					; run mesh bed compensation procedure & save map

Now my question is how I should account for the Y-Offset (G31) of the BL-Touch (36mm). Should I increase the first Y-value by 36mm (Y36:350) or should I reduce the second value (i.e. Y0:314)?

Thank you for your help!

wieman01

BoA

@wieman01 Y range is limited only from one side. Y=0 coordinates can be reached by bltouch - it just moves nozzle to position Y=36, and then proble is at Y=0.

But.. if nozzle can go only to Y=350, then probe can reach only points with Y <= 350-36.

So M557 would have Y range Y0:314, as any higher Y is out of reach of probe tip.

CCS86

Add the offset to your grid definition. So, you could run Y-36:314, but would likely run Y0:314, since you can't print below Y0.

wieman01

@boa said in Question: BL Touch Probe Offset & Mesh Bed Leveling:

@wieman01 Y range is limited only from one side. Y=0 coordinates can be reached by bltouch - it just moves nozzle to position Y=36, and then proble is at Y=0.

But.. if nozzle can go only to Y=350, then probe can reach only points with Y <= 350-36.

So M557 would have Y range Y0:314, as any higher Y is out of reach of probe tip.

Thank you, that makes sense. I'll change the settings accordingly. This could be reason why bed leveling appears to be slightly off.