HDPE for Vavuum Table

[Hack]

I am going to either build or buy a small vacuum table soon and am considering making one out of HDPE. My concern is how porous is this? Will it leak air bad? I am planning on using a shop vac for my vacuum. Perhaps 2 if need be due to size. I would like to make one that is 12" x 24" and use is for cutting and engraving plastic sign material. I will bemaking this 2 zones hence the 2 vacuums each of equal size.

Any input?

Thanks

Dan

[CNC Pro]

The HDPE should work. I’ve used MDF and even particleboard for vacuum tables (sealing them with epoxy paint used for sealing concrete (garage) floors.
One note on using plastics for vacuum tables: I’ve had CNC technicians describe router spindles that were “fried” from static build up from plastic vacuum tables.

[Hack]

I was thinking that I would drill a series of 1/4" holes at 1" on center across the entire top of the vacuum table for the holddown. Is this ok or should I go with smaller holes or different spacing perhaps?

Thanks

[mpstech]

CNC Pro you are right.

Any time you are using plastics and moving air/particles across it
you should run some type of ground to decrease the buildup
of the electrical charge on the plastic.
On vaccuum systems using pvc and other plastics it is common,
and a safety practice, to secure bar copper wire to the inside
of the plastic pipe runs. These wires should return back to a single
point and then connect to a good ground at your electical outlet
or other source. A good ground is critical or charge will build up.
On a vaccum table you should connect wires at several points
or use sticky sided copper tape on any avaliable surfaces, and then wired
back to ground.
If your ground source is at a plug or outlet it is also common to
connect your wire through a 10Meg Ohm resistor to severally limit
any current flow if somehow the ground becomes power due to
shorting or other physical electrical fault.
In fact all metal bodied tools, like router or spindle bodys
should be connected like this . If you use an ohm meter
you will see the metal case or body is shorted to the round
third prong and niether of the flat prongs are connected to
the body. If they are, have the tool checked, or buy a new one,
cause it's a shock hazard.
I regularly discharge myself and nylon jacket (highly static prone) after removing it by touching a static mat. You can feel the static charge bleed from the coat. The anti-static mat is a conductive rubber mat connected to a plug ground through a 10M resistor.
I digress.

[jfc11]

Hi,
I am making a vacuum table right now...I am making from 3/8 thick lexan..it will have a 12 x 22 work area with 8 zones.....I have a manifold block with 8 valves attached to be able to turn zones on and off as needed....
Also.....didnt you have some plans for a drum sander......I bought some router plans off of you but now when I go to your site it is just advertisments
Jim