Documentation Question



  • Hi,

    I was reading this the other day:

    https://duet3d.dozuki.com/Wiki/Using_mesh_bed_compensation

    It contains these two statements:

    You can stop using a height map by sending command G29 S2.

    Cancel any existing bed compensation by sending M561

    I was under the impression that they did the same thing. Yes? No?

    If "yes" then perhaps some editing is in order.


    Also there are these two statements:

    Send M208 S1 Z-3 to temporarily allow Z moves down to Z=-3mm. This is to ensure that you can lower the nozzle all the way to the bed in step 5.

    You may need to send M564 S0 to allow movement lower than where the firmware thinks Z=0 is.

    Are these not addressing the same issue but in two different ways. Yes? No?

    If "yes" then perhaps some editing is in order.


    Just thought I would mention while it was on my mind, it will be gone by tomorrow. 😉 Thanks.

    Frederick


  • Moderator

    DC42 would have to say for certain, but I think the difference is that M561 is an older command and used to refer to the 5 point plane created by G32 which has been superseded by mesh compensation, and now either command work in the same way to cancel any active bed compensation. So perhaps in a very old firmware they were different (or G29 S2 did not exist yet).

    In the summary of gcode commands at the end it says as much

    M561 Clear height map (same as G29 S2)

    @fcwilt said in Documentation Question:

    Send M208 S1 Z-3 to temporarily allow Z moves down to Z=-3mm.

    This should probably be changed because it's not the best way to do it. Again, perhaps in the past before M564 S0 existed.

    Thanks for the heads up, I'll make some edits for clarity.


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