Re: [CAD_CAM_EDM_DRO] seeking CNC conversion advice

I'm definitely not an authority on the subject of CNC conversion however, I was in your shoes just a few months ago. And now I have a converted CNC Bridgeport that operates very well. I'll outline the components I used. 40in/lb Allen bradley servo motors for X, Y, and Z (you definitely dont need anything that large) 2.2 ghz celeron computer running Mach2, Robert Campbells Sound Logic breakout board and Geckodrive G320 Servo drives. Find a suitable Power supply and You'll have a very reliable CNC control. Ebay is a good place to pick up DC BRUSH SERVO motors. Be prepared to replace the encoders, they need to be 200 line quadrature and US Digital has them for around 40 dollars a piece. The part number is E5S-200. The motors need to be under 80 volts and 20 amps because thats what the Geckos are rated at. However you can use motors with higher rated voltage and just run them at lower voltage to accomodate the drives. You lose some speed but not torque providing your power supply will
provide the amperage. DC servo motors are rated like this: 20v/k whick means 20 volts per thousand RPM. And say the motors max speed is 2500. You would need 50 volts DC from your power supply. That is the trickiest part. Motor selection and assembling a suitable power supply. The rest of the components are basically plug and play practically. Do a web search for "Gecko wiring" and you'll find a PDF that is a good example of a working CNC system. And as far as cutting gears with a rotary table, Accuracy would depend on the precision of the machine and rigidity of the setup. The software and drives are very precision. Thats all I know about it. :-)
cloutiertom <tomasc@...> wrote:I just ordered a Rong Fu 45 and am dying to convert it to CNC.
Basically, I know how to spell CNC, but that's about it. I'd like to
buy parts that are known to work either on eBay or from a surplus
house, put them together, and start using the mill! I do research
work all day long and much of the night and would rather not have to
re-invent the mill. I'm sure my questions have been asked many times
before, but any help would be greatly appreciated.

I'd like to use servo motors. What size, voltage, drivers, etc? Is it
feasible to drive the screws directly without belts and pulleys?
After the mill is CNCed can it still be used manually? Is converting
to ball screws a must? Is the same size motor suitable for driving a
rotary table? Can a servo-driven rotary table be accurately
positioned for jobs such as cutting gears?

That's it for now! Thanks,

Tom Cloutier





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