G29 on a delta and probe offset



  • I've been running my delta printers on Duet 2 wifi and ethernet boards for many years without using a z probe. I had a couple of BL Touch classics sitting around that I ordered a few years ago and thought I would finally get around to trying them. I have the probe setup and have been experimenting over the last few days.

    When I do a G29 I noticed that it cuts out the area circled at the top. I tried doing an M564 S0 H0 to let it go out of bounds but that did not make a difference. The other observation is that the probe points do not seem to take into account the offset on my probe.

    Anyone have any insights on this? Attaching my config.g and bed.g files

    Probe Video on Youtube

    bed.g
    config.g

    Screenshot 2020-10-16 160516.jpg Screenshot 2020-10-16 160512.jpg

    Screenshot 2020-10-16 162444.jpg



  • BTW I am running 3.2 Beta 2



  • I missed this in the console. It is skipping because it can't reach it. If I use M564 S0 H0 it does the same thing. I thought that might allow it to move outside the normal range.

    a696eeb9-9e18-48c5-bf2b-ff136cc4f2fb-image.png


  • Moderator

    You'd have to increase the size of your reachable area. It's not going to ignore the limits during G29 (apparently) though I can see why you may expect it to. I think M564 is intended for manual input from the user rather than automatic moves like in G29. If that makes sense.

    It's also worth noting that it will extrapolate the heightmap outside of the probed area, so missing a couple points there might not have any real impact.

    Using a offset probe like the BLTouch on a delta is problematic for a few reasons. Effector tilt mainly. This would be another. Using a nozzle contact probe is preferred.

    This is also common with non-delta printers as well and it's common to have to adjust the M557 range to accommodate the probe offset, otherwise it will just skip points it can't reach.


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