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

----- Original Message -----
From: Bill Vance <ccq@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, November 05, 2002 2:49 PM
Subject: Re: [CAD_CAM_EDM_DRO] replacing feed screw with a hydraulic
cylinder


> On Tue Nov 5 09:53:55 2002, Jon Elson, <elson@...> wrote:
>
> >al5502 wrote:
> >
> >>Did somebody try to get rid of the feed screw all together
> >>and replace it with a hydraulic cylinder?
> >>At the first glance it may present several advantages:
> >>no backlash, big force at low cost.
> >>
> >>
> >We go through this every 6 months or so. It looks neat at first glance,
> >and if you
> >have lots of hydraulic gear around, might even be affordable.
> > Proportional (Moog)
> >valves are REALLY expensive, like $3000 and up! The hydraulic pumps are
> >expensive,
> >massively power-hungry, and LOUD! The hazards of a hydraulic leak at
> >3000 PSI
> >are very serious. You get oil injected under the skin, and it poisons
> >you. A flexible
> >line blowing off can also be dangerous. If there is any air in the
> >system, it tends to
> >go crazy with oscillation. The performance can be iffy, too, with
> >jitter and stick-slip
> >friction.
> >
> >I think if you add up all the parts costs, even surplus, you could go
> >out and buy a complete
> >ballscrew retrofit and servo drives new!
> >
> >Jon
>
> All too true, but here's a question:
>
> >From the accuracy/resolution standpoint, what about slapping an encoder
and
> ballscrew/acme thread/timing chain onto a hydraulic motor, and as a way to
> ditch some of the more complicated servo power supply/amplifier/control
issues?
> looks do-able, at least at first glance.
>
> Bill
>
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