Sunday, February 10, 2013

Prototype 5-Axis CNC Board

Since I'm working on some CNC firmware, I thought I needed a test platform.  I didn't want to rip-apart the CNC so I decided to build a new 5-axis board using the new Pololu stepper drivers. These are nice little cheap boards and their advantage over the ubiquitous A4988 drivers is that they don't need cooling up to 1.5A per phase.  This makes things way easier, since those tiny little heatsinks for the A4988 chips are scattered all over my apartment, double-sided tape all linted up so they won't stick, just waiting to be stepped on.  They hurt even more than stepping on a Lego block, little buggers.

Anyway, I figured I should just go to five axes, which would allow me to control the 3D printer eventually (1X, 1Y, 2Z, 1E).  So I built a protoboard test board:

I laid out the board and soldered it up.  It was pretty easy except for having to drill a few extra holes in the power-rails to get the spacing I wanted.  After electrically testing everything I decided not to blow all 5 drivers simultaneously on a meticulously copied wiring error, opting instead for only two.

The MCU controlling the whole mess is an Arduino Uno.  I have the step pins on PortD and the direction pins on PortB, which allows fast bitwise operations to be used for stepping.  While picking up the stuff for the prototype board I also bought a proto-screw-shield, wanting a more resilient mounting option for the Uno:

I have the early version of my CNC firmware loaded onto the Arduino.  After firing up the serial terminal, I had the thing running!

Not super crazy, but still rewarding nonetheless.

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