Re: Van Norman #12 Milling Machine

Bridgeports use an air cylinder and you adjust the air pressure.
Darrell

----- Original Message -----
From: Jon Elson <jmelson@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: Sunday, January 23, 2000 10:24 PM
Subject: Re: [CAD_CAM_EDM_DRO] Van Norman #12 Milling Machine


> From: Jon Elson <jmelson@...>
>
>
>
> Dan Falck wrote:
>
> > From: Dan Falck <dfalck@...>
> >
> > At 11:31 PM 1/22/2000 , you wrote:
> > >From: Jon Elson <jmelson@...>
> > >
> >
> > >If you put a ballscrew on the Z (knee) axis, you will almost certainly
need
> > >a power-off brake to keet the knee from crashing to the bottom of
> > >travel when the power is off, or the system is in e-stop. This may
even
> > >be true with steppers, depending on how much they drag with power
> > >off. The will also be true on machines where the entire vertical head
is
> > >raised and lowered on a dovetail slide.
> > >
> > >Jon
> > >
> >
> > On my Rf-45 bed mill/drill the whole head assembly runs up and down on a
> > dovetail column. To keep it from crashing into the table when the power
> > goes out I have two sets of gas springs and some heavy duty springs
counter
> > balancing the head. I have sprockets on top of the column and chain
> > running from the head, over the sprockets and down the back to the
springs
> > and cylinders. It works pretty well. Weights would probably work just
as
> > well.
>
> Neat! Actually, the weight required to counterbalance the head would be
> acceptable, but the gas springs add a lot less mass. the counterbalance
> weights would DOUBLE the mass when the head is moved. For a knee,
> I think gas springs are the only way. Unfortunately, those would be BIG
> gas springs. Maybe, one could come up with old oleo struts from aircraft
> landing gear. That would be about the right size.
>
> Jon
>
>
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