Some quick ideas

[alohre]

Hello, I'm in the planning phase of making my own cnc mill. This will be a small one to start with, based on old printer steppers. After reading a lot about steppers, drivers and so on, my question is: Is This enough to drive a stepper from a printer ? As far as i've understood, the cnc software outputs on two pins on the paralell port for each axis with "use" and direction. Is it as simple as putting a Pic receiving from these pins, and outputing pulses to the correct pins on the beforementioned driver according to the signals from the paralellport ? also, feeding the steppers from a ATX power supply (one or two.). Does this seem as a feasible solution ? This is not a big mean cnc we are talking about, perhaps with a millable surface the size of a piece of A4 paper.

Please lead me in the right direction if I am way of

[Jan Rune]

Du vil heller bruke en dedikert motordriverkrets isteden..

Søk på Motordriverkretser hos elfa.se isteden...

Og kjøre 2-3 relative små stepper motorer fra ett AT power supply burde å gå helt fint

(Just some norwegian about the IC and the power supply)

[alohre]

Does the cnc software output pulses for the steppers, or do I need some sort of pwm ? I've changed my mind about the PIC, opting to use logic ic's instead. Can I simply make a logic chain, outputting pulses from i.e turbocnc, straight into a transistor feeding the steppers from a ATX power supply, or do I need another step doing PWM ? I found a driver ic at elfa, but as this is a educational experience for me, i'd like to do it a bit more "manual"

[spalm]

All of the options you have described will work. But the devil is in the details.

Logic ICs, FPGAs, or Micros can do the conversion from the STEP and DIR signals to run a stepper. You will need some hardware here; the PC will not output signals that go directly to the transistors/motors. The current to drive these things can quickly get rather large. Start with small steppers (I am not sure which kind of printer you got these from, some printers or copiers have quite large motors.)

A site with several proven designs with schematics and layouts is PMinMO. There are several solutions with varying degrees of logic involved, including a PIC.
www.pminmo.com

If you want to go the Microprocessor route, search for Stepper Motor at Microchip. They have several application notes that are a pretty good read.
www.microchip.com

Steve