Re: [CAD_CAM_EDM_DRO] Re: Re: replacing feed screw with a hydraulic cylinder

blown_mgb_v8 wrote:

>Ray, please do elaborate. I will have the machine here in a couple
>days and would like to learn as much about it as I can. For
>instance, since the hydraulic system is already in place, what would
>it take to put linear encoders on the thing and replace the air
>logic with a PC?
>
>

Well, the big kicker here is that you need to get electrically-actuated
proportional servo
valves of adequate capacity for the machine. These are not expensive,
they are REAL
expensive! You could likely buy a working Bridgeport Series-II CNC
machine for what
a set of 3 Moog or Parker-Hannifin prop. servo valves would cost!
Conceivably close
to $10,000 for a set of 3. Then, you need servo amps designed to drive
a prop. servo
valve. I have the prints for how A-B did it on the 7320-series of
controls. They added
a 400 Hz sine wave to the velocity command signal from the computer to
keep the
valve's spool from settling in one spot. I don't think you could get a
system working
without some kind of dither like that. (A small software change could
put the dither
in from the CPU, instead.)

Jon