I haven't gotten much done on the hardware side of things lately, but I've been busy with the electronics of the R3 platform I'm working on. Above is the first draft of the parallel port adapter that will be used for the first round of machines. This board allows a PC running Mach3, EMC2, or any other G-Code interpreter with a parallel port driver to control up to 4 RepRap/Makerbot stepper motor drivers and has separate inputs for X, Y, and Z axis home, emergency stop, and limit switches, as well as a few additional outputs and it exposes the enable functionality of the stepper motor drivers, allowing you to disable all stepper drivers if needed. I'm planning on using Mach3 for the initial prototypes and then moving to a microcontroller based G-Code interpreter (possibly based on ) once development is further along.
Other than the main PC breakout board, I've also designed boards for mechanical end stops (seen above) and a stepper signal splitter board (seen below) that will allow two stepper drivers to be controlled by the same signals, allowing for some interesting mechanical drive options.
While designing these boards, I tried to keep them single sided if possible, keep the required part counts low, and use big parts where applicable to make them easy to construct. The idea is to make them easy to "bootstrap" via traditional DIY PCB etching methods and easy to mill once I've got a machine up and running.
