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G31 probe offset confusion

Posted by o_lampe 
G31 probe offset confusion
January 03, 2018 01:01AM
Sorry to ask it here, but I couldn't find any info about X/Y-offfset of a proximate sensor on a Delta in the DuetWiki.
I figured out, I can use G31 to set X,Y and Z offset between nozzle and sensor.
I generated the bed.g with the same offsets I use in G31. Now it probes (G32 ) without crossing the outer limits.

The X&Y parameters seems to be "distance from nozzle to probe", but Z seems to be " distance from probe to nozzle".
In my case, the probe is 35mm to the right ( X35 ) and 10mm to the front ( Y-10 ). It is also 5.1mm below the nozzle, but here I have to use Z5.1 instead of Z-5.1?![

IDK if using G29 cares about the X/Y offset. It seems it does the same routine with or without the offset.

Should I use XY offset for a Delta at all? It seems, the effector is lower the more I move it towards the Y-tower. That seems to be related, since the probe is mounted between the Y-rods.

Edited 3 time(s). Last edit at 01/03/2018 01:27AM by o_lampe.
Re: G31 probe offset confusion
January 03, 2018 02:17AM
Quote
o_lampe
The X&Y parameters seems to be "distance from nozzle to probe", but Z seems to be " distance from probe to nozzle".
In my case, the probe is 35mm to the right ( X35 ) and 10mm to the front ( Y-10 ). It is also 5.1mm below the nozzle, but here I have to use Z5.1 instead of Z-5.1?!

That's right. The G31 Z parameter is trigger height. The X and Y offset parameters were added later, and were defined as distance from the head reference point to the probe, just like tool offsets are.

Quote
o_lampe
IDK if using G29 cares about the X/Y offset. It seems it does the same routine with or without the offset.

Defining the XY offset correctly will ensure that it doesn't try to probe off the edge of the bed.

Quote
o_lampe
Should I use XY offset for a Delta at all? It seems, the effector is lower the more I move it towards the Y-tower. That seems to be related, since the probe is mounted between the Y-rods.

It sounds to me that you have effector tilt that varies with Y position. See [duet3d.com].

Edited 1 time(s). Last edit at 01/03/2018 02:17AM by dc42.

Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: G31 probe offset confusion
January 03, 2018 08:56AM
Quote

Quote
o_lampe
The X&Y parameters seems to be "distance from nozzle to probe", but Z seems to be " distance from probe to nozzle".
In my case, the probe is 35mm to the right ( X35 ) and 10mm to the front ( Y-10 ). It is also 5.1mm below the nozzle, but here I have to use Z5.1 instead of Z-5.1?!


That's right. The G31 Z parameter is trigger height. The X and Y offset parameters were added later, and were defined as distance from the head reference point to the probe, just like tool offsets are.

What I wanted to point out is the fact, that the z-heigth has a different sign.
It is Z5.1 instead of Z-5.1 ( although it is 5.1mm lower than the nozzle )
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