DB37 Extruder/Hotend hookup board

  • Hi, I'm giving PCB design a shot, and I'm aiming to make a Breakout board for a DB37 connector to allow me to easily swap out Hotends/Extruders.

    I'm going to be having the connector printer side, (extruder/hotend wired directly -> cables -> Connector -> Duet), so I'm designing a board to go on the top of my printer to connect to.

    I'm not using the expansion headers, as I'd like to keep it generic. My first pass at a design is here https://easyeda.com/keyz182/DB37Breakout - note, it's a mess, I'll be taking a second pass to make pinouts more sensible for an easier board layout, the main thing on this pass was to ensure I captured all the connections I needed.

    I currently have:

    • E0Stepper - 4Pin
    • E1Stepper - 4Pin
    • E0Heater - 2Pin
    • E1Heater - 2Pin
    • E0Temp - 2Pin
    • E1Temp - 2Pin
    • XSensor - 3Pin
    • ZSensor - 3Pin
    • PartFan - 2Pin
    • HeaterFan - 2Pin
    • 24V1 - 2Pin
    • 24V2 - 2Pin
    • 12V1 - 2Pin
    • 12V2 - 2Pin
    • P5 - Spare 2 pin header
    • P6 - Spare 2 pin header

    So my question is, do you think I'm missing anything? Any suggestions for anything else that could be useful? What else would you want on a board like this?

    Also, would you do/wire anything differently? I did consider a concept of a "smart" hotend, with e.g. a small storage chip or similar with an ID stored on it, hooked up over I2C or SPI to the Duet, so I could load a different config.g/macro based on what's attached. I imagine I'd have to make changes to the firmware to be able to achieve that though.

  • I have used DB25 for many projects over the years and your answer lies in the QUALITY of the connector.

    Basically the cheap chinese connectors are not much good for more than half an amp once you have scraped off the vapor thin gold plating. Insert connector say 10 times and hey presto, no more good contact !

    Even the name brands have dropped their quality so unless you source genuine known quality you will have some degree of trouble i.e. Your thermistor readings go noisey.

    A good connector pin is OK up to a couple of amps but keep in mind the stepper generates high current spikes so you usually need a better sized pin than the DB series of connectors provide.

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