Reducing load/unload fail consequences

Discussion in 'Tool heads & ToolChanger' started by Sylvain, May 22, 2020.

  1. Sylvain

    Sylvain Member

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    Hi everybody

    I'm building my Tool Changer.

    I see on this forum severall posts about load/unload fails...

    Is that a reccurent issue ? I think that if it was possible you would have done it, but is that possible to solve this by tuning load/unload gcode ?

    I understand that when there is a load/unload fail, this is the panic... Some of you are waiting conditionnal g-code upgrade.

    In order to avoid the load/unload mess, would it be possible to :

    • add a switch that detects the tool head wants/will catch a tool (whatever the tool number) - somewhere on Y axis, near the rear
    • add a swtich on Tool head
    • build a external (arduino like) electronic board which check if after the first switch activation, we get a unload/load sequence in the next 20 seconds for example (detected trhough the desactivation/activation of the 2nd switch).

    If not, the arduino board drives a Duet "hard reset" (through a relay ??). You lost your print but you don't lost your Tool Changer.

    First switch could be replaced by gcode saying to external board "I want to unload/load" through the Duet.

    Sorry if this is totally stupid.

    Thanks !
     
    #1 Sylvain, May 22, 2020
    Last edited: May 22, 2020
  2. dc42

    dc42 Well-Known Member

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    Amongst the suggestions for detecting when a tool change may be going wrong are:

    1. Add a switch to the tool pickup to detect whether a tool is loaded. The wiring loom already contains two wires for such a switch.
    2. Add switches to detect when each tool is docked. This could be done using a microswitch on the tool dock. However, when Hemera tools are used in conjunction with Duet 3 and tool boards, it's simpler to put the switch on the tool board because then you don't need are more wires going back to the Duet. The switch can be connected to the IO_0 connector on the tool board and is read via the CAN bus. I have some small microswitches on order and when they arrive I will look at modifying the Hemera tool printed parts to accommodate them.

    Checking the state of the switches can be done using conditional GCode in the tool change files, so no need for additional electronics.
     
  3. Spoon Unit

    Spoon Unit Well-Known Member

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    I believe that one of things you can do to enhance repeatability of location is to use microswitches as endstops for X and Y instead of relying on detecting motor stalling.

    https://www.thingiverse.com/thing:3843642

    With that done, you can retune your pre and post macros and achieve pretty damn good repeatability. Even so, I've had one or two errors I can't account for and one I can (the endstop screws for Y became loose - solution. check tightness from time to time).

    After that, checking for presence with switches would be the next level of reliability.
     
  4. Sylvain

    Sylvain Member

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    Thanks for you answers.

    I finnaly understood that it is possible to check with conditionnal Gcode, without other electronics.

    What I plan to do :
    switch on carriage
    switch on each tool (4 switchs)

    and conditionnal to check.

    Best regards
     

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