Thursday, September 26, 2013

Mini CNC build

Got a new toy to tinker with the other day. Its an old Ram Optical microscope system, originally used at my Dad's work for inspecting parts.

They upgraded quite a while ago to a newer system, but aside from the ancient desktop computer that records the measurements, this machine is still in very good shape. My Dad wants to set up the video microscope on the bench with a small LCD monitor, and I plan to use the rest of the machine for a small CNC build.  It should be a perfect platform for a small CNC for milling circuit boards and engraving wood, plastic, and maybe aluminum. the envelope is small, only about 4x8x8" but I rarely need circuit boards larger than 4x8" anyway. The machine is highly accurate since it was meant for taking measurements using the microscope, I just need to come up with a spindle and motor for it that is also accurate enough.

The drivers that were used in this machine are controlled over RS232, either by a computer or directly with the joystick. They are also overkill for the small NEMA 17 stepper motors that drive this machine. I'm sure I could program a microcontroller to move the machine around, but I'm less sure I could easily program it to interpret G code into commands for the controllers. So, I think my best bet is to replace the driver completely, in favor of the TinyG CNC controller. It accepts G code streamed over USB and has the appropriate motor drivers on-board, for simple setup and use. I've already set to work determining the pinout of the DB9 motor connectors on the side of the case, and the wiring scheme of the current control box so that I can easily install the new control board.

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