Thursday, February 25, 2010

RepRap Motherboard, Homebrew Style

Homebrew Motherboard

Here's my homebrew motherboard freshly kitted out.

The arduino sits in a reverse shield of my own design, with pin sockets either side and bridges going from one line of sockets to the other. Hard to see in the photos are some wire clips that hold onto the mounting holes to help keep it steady. It's surprisingly snug with this arrangement, barely moving even when I connect the usb plug.

The ATX connector is made simply from some tinned copper wire. I'll probably put in a proper connector when one becomes available. The 12v connector in the middle of the board is vestigial, and will be removed when I add some pins for the ATX 12v extension. Multiple 12v and ground wires are absolutely essential, considering how much current will be drawn from them, as well as the likelihood of vibration.

The jumpers near the motor controllers are connected to MS1-3 so I can change the microstep amount simply and quickly. Z needs none, extruder needs it all and I'm still undecided on how much X and Y need.

At the bottom of the board next to my MAX6675 are a pair of power mosfets for controlling the extruder heater and one other item- bed heater or fan or something. The mosfets are IRL3803s which according to my calculations can handle 16A with no heatsink and 4.5v on the gate.

The headers between the arduino and the atx connector are for the end-stops which I'm yet to make.

Bottom View

The bottom view shows a rat's nest of point to point wiring which I'll clean up if it proves to be problematic. Signal lines next to high frequency high current PWM lines are usually a recipe for disaster, but the motor modules are so small that I'll just have to see how I go. Twisting and decoupling helps immensely, but is by no means a magic pill.


  1. Great!

    You know, many times this boards are expensive and some times out of stock on Makerbot. I really like that Arduino were chosen for hardware, because then we can build our own boards and even buy them if we prefer :-)

  2. Hello, I love this blog was exactly what I was
    need I live in Brazil and I am sorry for my english bad, I'm curious to know if you can
    help me regarding this machine with the firmware
    Arduino and Pololu together as it does not start
    work with this firmware if you can send me
    certainly some documentation that I would be happy.