Are toolboards hot-swappable?



  • I'm curious that if one were to build a printer using a robotic tool changer that would pass through the electrical connections (Example: ATI pogo-pins ) would the Duet 3 be able to handle toolboards being connected and disconnected mid print?

    A potential downside I see is not being able to keep the unused tools heated when not in use, but if this is possible maybe some of you have ideas on how to mitigate this issue.

    Thanks.


  • administrators

    I can see two issues with hot-swapping tool boards:

    1. Because of the capacitors on the VIN rail, there would be a large surge current when the pogo pins mate. I tried hot-plugging one and there was a fat spark. You would need to mitigate this, for example by connecting the tool board initially with a resistor in series with VIN, then bypassing the resistor after a short delay.

    2. You would need to wire it so that the CAN bus isn't broken when the board is disconnected. You could wire the CAN bus to the pogo pins and onward from them, and then use just 2 wires and 2 pogo pins to connect the CAN bus to the tool board.

    BTW there is a patent (bought by Stratasys) on tool changing 3D printers using pogo pins.



  • @dc42 Oh yes, I’ve battled sparks building quadcopters, but the ESCs on them have capacitors on the input wires to prevent that. You can even get anti-spark XT90 connectors. Or perhaps a solid state relay could be used to connect/disconnect power during the tool change cycle.

    Looking at patent US8926484B1 seems to be problematic though. The way it’s worded, if the tool changer connects any sort of electrical connection then it conflicts... I bet that’s why E3D only mechanically couples their tool changer.


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