Lift Z during during toolchange



  • I am trying to add a servo driven purge mechanism to my machine . The problem is that it needs to clear the bed ( or printed part) by lifting the head 15mm. I need to use the purge bucket during tpost but also during tfree . So , I can add something like G91 G1 Z15 F600 G90 to tpost and tfree and it would be fine during the the first tool selection (tpre>tpost) but it would lift the head by 30mm every other tool change(tfree>tpre>tpost). Is there any wizardry to make it lift only 15mm ? tool offsets maybe?



  • @Ntrack
    When you initate a tool change the Duet stores the current tool coordinates as if you'd issued the following G60 command:

    G60 S2
    

    You can also store coordinates in S0 and S1

    Using this stored location (S2) you can move up 15 mm by issuing a G1 command with the "Restore" argument R

    G1 R2 Z15
    

    This will move to the location stored in slot 2, with an offset of 15 in the Z axis.

    I find this much easier to reverse than switching to and from relative coordinates. For example, you can perform whatever purge maneuvers you need to do and then just issue the command:

    G1 R2 X0 Y0 Z15
    

    to return to 15mm above the last printed point on your model.

    G1 R2 X0 Y0 Z0
    

    will put the tool back in contact with the model and should probably be the last instruction in tpost.g



  • @SteveYYC thats exactly the kind of magic I need. Thank you for that.



  • Not related to my initial question but I’m curious If I’m writing the coordinates with G60 are persistent.If I issue G60 S2 and the power cycle the machine will I be able to use those coordinates with G1 ?


  • administrators

    @Ntrack said in Lift Z during during toolchange:

    Not related to my initial question but I’m curious If I’m writing the coordinates with G60 are persistent.If I issue G60 S2 and the power cycle the machine will I be able to use those coordinates with G1 ?

    They are not persistent.



  • Thank you, didn't expect it to be TBH. Otherwise it would have been used in power recovery


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