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

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.

The stock position control of the hydraulic ram was not based on fluid
volume. Ram position was based on a set of air holes in a plate that
slid along with the ram. You could think of the air part as an absolute
linear encoder that used air instead of electrical impulses. If that's
not confusing enough, I could elaborate.<g>

Ray

> Subject: Re: Re: Re: replacing feed screw with a hydraulic cylinder
>
> Guys,
>        I've been following this thread, and although I've never done
> it, I wonder if the coefficient of expansion of the hydraulic fluid,
> would cause some accuracy problems? On a cold day, it would cut
> differently than on a warm day, and would you have to reset your Z axis
> every time the temperature changed?
>
> Marv Frankel
> Los Angeles