Z Home - Multiple probe average

dm86

Hi all,

I'm getting fairly variable reads using the IR sensor on glass.

Is there an example anywhere of taking multiple reads and averaging them out? I can't seem to find it but maybe I'm searching thewrong terms.

Thanks

Veti

see
https://miscsolutions.wordpress.com/mini-height-sensor-board/

Glass (with or without coatings such as hairspray, PVA or Kapton tape): works as-is if placed directly on a PCB bed heater or other surface that does not reflect strongly. If there is an aluminium heat spreader or bed plate underneath the glass, then either paint the aluminium surface matt black (see below), or put a sheet of matt black paper between the glass and the aluminium. Coatings on the glass affect the trigger height slightly.

fcwilt

@dm86 said in Z Home - Multiple probe average:

Hi all,

I'm getting fairly variable reads using the IR sensor on glass.

Is there an example anywhere of taking multiple reads and averaging them out? I can't seem to find it but maybe I'm searching thewrong terms.

Thanks

Here is my Z probe M558 command:

M558 K0 P8 C"!io8.in" H2 F300 T9000 R0.2 A10 S0.01

Notice the A and S parameters.

If you used A5 S-1 you would take 5 readings and they would then be averaged.

Frederick

dm86

@fcwilt Thanks, totally missed that. For some reason was expecting it to be on G30.

dm86

@Veti I have my bed on a blue silicon thermal transfer pad which gives a really good backing for the sensor. I've been using it well for quite a while but I've found these sensors lose accuracy after a while. I've always assumed its the cap drying out but never really investigated.

Multiple probes seems as easy way to get a little extra life before replacing.

dm86

@Veti Thanks again Frederick, got it working now. However I couldn't find reference to the S-1 command anywhere, do you know where this is documented?

The GCODE Library just appears to just say,
"Snnn Tolerance when probing multiple times, default 0.03mm".

Does -1 just force the max number of probes?

fcwilt

@dm86 said in Z Home - Multiple probe average:

@Veti Thanks again Frederick, got it working now. However I couldn't find reference to the S-1 command anywhere, do you know where this is documented?

The GCODE Library just appears to just say,
"Snnn Tolerance when probing multiple times, default 0.03mm".

Does -1 just force the max number of probes?

It may not be documented as such but it follows from what S determines.

The probing continues until two consecutive readings are within the S value.

What are the odds that two readings are going to be within -1?

Frederick

Phaedrux

@dm86 said in Z Home - Multiple probe average:

I couldn't find reference to the S-1 command anywhere

The A and S parameters control multiple probing. Probing is repeated until two consecutive probe attempts produce results that differ by no more than the S parameter; then the average of those two results is used. However, if the number of attempts specified by the A parameter is reached without getting two consecutive results within tolerance of each other, no further probe attempts are made and the average result of all the attempts is used.

I guess it's kind of hidden in that paragraph. I should add a note in there about using S-1 to force the averaging.