Move the extruder without tool selected

  • Hi

    I have a home built tool changer along the lines of an e3d system but to save weight and allow for a heated chamber I am using a suction cup to couple the tools and a flexy drive to the tool with a single extruder motor serving all the tools. For this design the tools and the tool holder have a splined shaft connection and if it is not aligned properly the tool change can fail. My intention was to giggle the extruder motor backwards and forwards a few degrees as the coupling was made so the splines would engage. So far my tests show this will work.
    The problem I have hit is the software will not let the extruder motor move until it has finished running the
    _ Pre.g file and selected the tool.

    I can think it would be posable with a four pole change over relay to switch to another driver but I am not shore that is a safe way to go and may damage the driver chips, so it would be better to find a solution in the software somehow. I have tried calling a sub program in _Prep.g to bring the tool head forward a few milimeters as I giggle the extruder but I still have the same problem.

    Does anyone have any idlers of a way forward so I can move the extruber as I pick up the tool?


  • administrators

    You can use M584 to assign the driver to both an extruder and an axis (e.g. the U axis). In normal use, use the P3 parameter in M584 to hide the axis. During the tool change, use M584 P4 to un-hide it, then you can use G1 U commands to move it. When the tool change is complete, use M584 P3 to hide the U axis again.

  • Just got a chance to try your suggestion and it works just fine, but I did have to put in a
    M564 H0 as U was not homed.

    Thanks for your help.

  • Moderator

    You could also use G92 U0 to set the axis as homed without allowing unhomed movement for all axis.

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