Re: [CAD_CAM_EDM_DRO] hydralic bed control

Ejay Hire wrote:

> Disclaimer: I haven't done specifically what you ask about, and I don't
> know how much backlash is present in a hydraulic system.
>
> If I were going to attempt this, and not a lot of people had said it
> wouldn't work, here is what I'd do.
>
> 1. No power steering pump. Hydraulic pumps are less than $100 and will
> last longer, run cooler, and provide more stable volume.
> Get them from Grainger or Princess Auto(The catalog, not the web store)
>
> 2. Linear encoders provide feedback to the Controller. This will have to
> be a closed-loop system
>
> 3. Electrically controlled variable rate hydraulic valves.
>
> With the proper controls, it wouldn't seem to be very different from a servo
> system.
>
> ----Original Message Follows----
> From: dave engvall <dengvall@...>
> Reply-To: CAD_CAM_EDM_DRO@egroups.com
> To: CAD <CAD_CAM_EDM_DRO@egroups.com>
> Subject: [CAD_CAM_EDM_DRO] hydralic bed control
> Date: Sat, 29 Jul 2000 07:38:06 -0700
>
> Hi,
> I have an old horizontal mill with a hydralic bed. Has anyone tried
> control of anything hydralic using a automotive power steering unit?
>
> Dave

Hi again,
Back in the dark reaches of my memory is the recollection that the first cnc's were hydralic and while they may not have been a
good as the electircal stuff they worked. I've spent some time talkng with one of the electronics people at Dowty Aerospace that
does a lot of test stuff and he assures me good hydralic servo valves are spendy.....really spendy....which is why I'm considering
using a power steering control unit.
The other option might be a series of solenoid valves with binary weighting. i.e. hydralic D/A. :-)

Dave

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