Question about M558 A and S parameters

fcwilt

Hi,

For those using a BLTouch (mine is v3.0) with the M558 A parameter greater than 1 what are you using for the S parameter (tolerance)?

Thanks.

Frederick

Phaedrux

Yes.

https://duet3d.dozuki.com/Wiki/Gcode#Section_M558_Set_Z_probe_type

Annn Maximum number of times to probe each point, default 1. Maximum, as of 2.03, is 31. Setting M558 A parameter to anything >31 set it to 0 instead of to 31
Snnn Tolerance when probing multiple times, default 0.03mm

fcwilt

@phaedrux said in Question about M558 A and S parameters:

Yes.

https://duet3d.dozuki.com/Wiki/Gcode#Section_M558_Set_Z_probe_type

Annn Maximum number of times to probe each point, default 1. Maximum, as of 2.03, is 31. Setting M558 A parameter to anything >31 set it to 0 instead of to 31
Snnn Tolerance when probing multiple times, default 0.03mm

OK that was confusing.

I asked what value folks are using for the S parameter and your answer was "yes".

I don't think the firmware will accept "yes" as a value for that parameter.

Frederick

Phaedrux

Well the default is 0.03 and I doubt most people will change the default.

For what it's worth I use 0.003, which I came upon by looking at the repeatability of the probe. This is quite a bit tighter than the default and I do have occasions where it will probe several times in a row. Usually it's only 2 or 3.

fcwilt

@phaedrux said in Question about M558 A and S parameters:

Well the default is 0.03 and I doubt most people will change the default.

For what it's worth I use 0.003, which I came upon by looking at the repeatability of the probe. This is quite a bit tighter than the default and I do have occasions where it will probe several times in a row. Usually it's only 2 or 3.

Is the BLTouch v3.0 generally able to do better than 0.03?

The value seems a bit large given that it is 30% of a 0.1 layer, the smallest layer height I use.

While I'm new to this mesh compensation feature it would seem that it would be good if the measurement accuracy was more along the lines of 0.01 or 10% of a 0.1 layer.

Am I worrying needlessly and 0.03 is just fine?

Am I expecting too much from the BLTouch?

Thanks.

Frederick

Phaedrux

Note the extra 0 in the value I use.

Check your repeatability by running g30 s-1 as you would during calibration multiple times and see what your deviation is.

fcwilt

@phaedrux said in Question about M558 A and S parameters:

Note the extra 0 in the value I use.

Check your repeatability by running g30 s-1 as you would during calibration multiple times and see what your deviation is.

Yes I did notice it was 0.003 which seems sensible.

I will do as you suggest.

Thanks.

Frederick