PCB based automatic tool changer (idea)

Discussion in 'Tool heads & ToolChanger' started by Dejay, Jan 10, 2021.

  1. Dejay

    Dejay Member

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    So after seeing the XChange I had the idea of maybe using PCB boards to implement an automatic tool changer.

    PCBs can be thick, are precise and cheap and easy to order. 3.2 mm circuit board would be plenty strong and stiff.
    Maybe you could insert and SMD solder the registration points for precise positioning. Like a ball and those bars on the E3D toochanging plates. You'd put both "halves" into the reflow oven to assure precise registration

    You could have a functional PCB where you just need to solder the mechanical registration points and the electric connector. In the simplest case that would just be pins sliding into some sort of socket (something like mill-max sockets). For the tools you could also save on wires to accommodate LEDs or temperature sensors or filament sensor.

    Maybe?
     
  2. HamJ

    HamJ Member

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    Very interesting idea! It would be really awesome if the Duet toolboard and the toolplate were merged.
    The size of the current toolboard makes it hard to integrate, when not attaching it to the Hemera stepper as intended.
     
  3. Dejay

    Dejay Member

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    Oh wow I hadn't even seen that toolboard. Very interesting! That toolboard would only need a single serial data connection plus VCC and ground, correct?

    Initially I was just picturing a simple PCB to reduce cost and weight (FR4 PCBs are fiberglass+epoxy and should be stonger than aluminium).

    But a merge between a super compact direct drive extruder, that toolboard and a tool plate would be really awesome. I've also been looking into PCB mounted brushless motors with encoders, which should save weight compared to a nema stepper motor. It should be even more lightweight than a nema14 motor if I understand it right. Like one PCB with an odrive like motor controller, and an encoder (measuring the filament movement).

    I've also had the idea that you could use the temperature coefficient of resistivity. In vaping devices you can use the pretty defined TCR of pure nickel, titanium or stainless steel wire to measure the resistance and therefor the temperature and heat up a coil with a single wire. So instead of a big heatblock and thermistor you could have a coil of nickel wire wrapped around the hotend just above the nozzle. Which could make the wiring and assembly of hotends even simpler and reduce the lag between heating, measuring temperature and change in temperature in the melt zone. Integrating all this into a single PCB and direct drive extruder could be pretty cool.
     
  4. HamJ

    HamJ Member

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    Correct, it basically requires only 6 wires (Vin, GND and 4x for CAN bus (back and forth). The only downside I can think of is that you might also operate the tool when it is in the parking dock (e.g. keep a standby temperature). So you would either require an additional spring probe connector at the dock or stick with a cable...

    I really like your other ideas. I think relaying on feed-forward controlled steppers might be the cheaper solution but probably not best in terms of power density...
     
  5. dc42

    dc42 Well-Known Member

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    You can probably get away with just 2 CAN wires, provided the cable length to the distribution board isn't very long. Ferrite beads with the right impedance on the CAN wires will help.
     
  6. Dejay

    Dejay Member

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    Thanks HamJ and dc42.

    Any ideas of what PCB mounted hardware one could use to replace the balls and rolling pins? I guess one could look into hardware for bearings (ball bearings and needle bearings). Then design the PCB so they slot in half way and touch "solder connections" that you apply solder paste to. Or maybe just hand solder. I figure solder should give strong enough connection if designed right for the loads and should be similar to brazing.

    Has anyone experimented with NFC or bluetooth mesh? With ESP32 so cheap that might also be an option. Then you'd only need to power connectors. But this is probably not worth the hassle compared to 2 or 4 additional wires for a bus connection.
     
  7. Maxime FRANCK

    Maxime FRANCK New Member

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