You might think I've completely forgotten about my 3d printer, but rest assured it is still receiving attention.
My main complain so far with the machine is that some of its prints were not very square. Often successive layers that should be on top of each other, ended up on a diagonal, getting more and more off axis. I didn't have much luck tracking down why this was happening, but I suspect it is a quirk of either the microcontroller not being powerful enough, or the firmware (Teacup) having a subtle bug.
So I decided to redo the electronics. I ordered a parallel port breakout board off ebay for a few dollars, same as I'd used on my CNC machine. This arrived and was duly installed:
These aren't designed to drive 3d printers so a little fiddling was required to make it work. X, Y, and Z on the machine matched up with the respective outputs on the board. The extruder was hooked up to the A axis, and the limit switches plugged straight in.<...