Re: Re: Re: replacing feed screw with a hydraulic cylinder

Hi Jim

I spent several sleepless nights a long time ago trying to figure out how
to use the existing hydraulic system under the control of a VIC-20. The
system positions based on the balance of air between the tape reader, the
offset air valves on the control panel, and a metal plate that slides
with the hydraulic cylinder. Any other way and you bring in all of the
problems of oil temp, viscosity, and dither in the modulating valves.
With these sliding monstrosities Bill Moog was able to get around all of
that and produce a machine that was fairly stable and produced repeatable
results. But to get that accuracy you had to make sure that the seals
were good, there were no cracks in the sliding plates, and the reader
surfaces had to be real flat and fit just right.

It would be possible to replace the tape reader with a bank of air
solenoids but you need something like 150 of 'em and a couple of rather
expensive PC I/O boards to drive them. The reader uses a block of 18 or
so 8 bit punches for each read. ( I could go out to the shop and count
one if you need me to.) Each read is a single positioning block. If you
did this, you would still be working at the speed of the machine which
was just a bit faster than molasses around here (Lake Superior) this time
of year. These hydrapoints were awesome to watch and filled with
features that other machine manufacturers hadn't even thought about when
they were new but they were not fast at doing it then. They are very
slow by today's standards.

You would also have the five hp three phase hydraulic pump sucking juice
from your power line like there was no tomorrow and making more noise
than a small airplane at 20 feet.

I've still got one sitting in a couple of pieces out there. I threw out
or sold the hydraulics and plan on a ball screw fit when I get both the
time and money in proximity to each other.

Ray

>    From: "blown_mgb_v8 <jblackwood5@...>"
> <jblackwood5@...> Subject: Re: Re: replacing feed screw with
> a hydraulic cylinder
>
> 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?
>
> Jim
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Ray Henry <rehenry@u...>
>
> wrote:
> > 
> > Hi Marv
> > 
> > I was thinking that the title of this thread was backwards because
>
> a Moog
>
> > Hydrapoint like Jim wants to convert uses hydraulic cylinders for
>
> axis
>
> > movement.  It seemed to me that Jim was wanting to replace these
>
> with
>
> > ballscrews.