Re: Vacuum Table

Bill,

One thing I've always done on vacuum setups is to have some sort of
positive stop on the workpiece so it can't shift sideways. Have a
locating pin in the workpiece which fits a hole in your vaccuum table
or have some kind of edge locating stops around the perimeter.

For large pieces even a shop vac will provide the needed hold down
force, but it won't always guarantee against sideways slippage.

Also, don't have large areas unsupported in the center of your
workpiece. I once had a 2' x 2' piece of aluminum 5/16" thick take
on a permanent bow in the center because it was only supported around
the sealing edges.

Another thing, if your pumps are oil less be very careful no moisture
is sucked into the vacuum port. I've ruined a couple of Gast oil
less pumps by allowing coolant into the intake.

Doug

--- In CAD_CAM_EDM_DRO@y..., "William Scalione" <wscalione@n...>
wrote:

> Anyone out there ever built a vacuum table for a cnc router? I am
> in the process of building a new larger router and would like to add
> a vacuum part hold down to it. I picked up a couple of vacuum pumps
> at the NC State University surplus today although I am not sure if

they

> will work for it yet. They are nice units direct drive high vacuum

lab

> units. What I need to know is what size and number of holes would
> I drill in a 4' X 4' table? I will probably add some valves to

section

> the table off, possibly go back and get another pump and section it
> into thirds, one pump for each section. Use only the sections I

need

> to, depending on the size fo the work. I was thinking of using an

acrylic

> sheet maybe 3/4" thick for the table. Will it require a large O-Ring
> around the edge or will just the holes be sufficent? Any tips would

be

> appreciated.
>
> Thanks
> Bill