Re: Dragging an old Sherline CNC into 21st century...
Andrew, the fist question has to be what part number are the stepper motors. So you can work out what current you need. Some of these older systems were 'unipolar' and the wiring of the motor is not suitable for the newer bipolar drivers.
I've used Chinese drivers for years without any problem, and even a new set of motors with a suitable driver is likely to be cheaper than the Gecho, but even before that you can try things out as Mach3 will run in NCMax mode. It is only the smoothstepper that does not mirror that through. It is only 3 channel though as it only supports one parallel port on the computer. It's worth giving it a run up to check things out.
Even though the steppers have probably had little use, the magnets can get weaker over time. On the Taig mills of that age we would be looking to replace them anyway, but with the small size of the Sherline there should be a few more years in them yet.
Lester Caine - G8HFL
http://medw.co.uk - Home of electronics for the Model Engineer