Vacuum Pod System

[reals8gy]

Hello,
I've got an SR34 and will be adding a blackbox soon.
Can anyone shed more light as to how a vac pod system operates?

I'm fascinated with the idea of holding the work off the table, so I can rabbet the edges, or any other edge profile without cutting into the spoil board.

Is it a series of small balls that operate as valves and the pod opens the valve, transferring the vac to very selective areas?
That seems beneficial because the leakage should be minimum maintaining excellent vacuum on the selected areas.

[rcrawford]

A blackbox won't work very well for vacuum pods. You'll get about 9"hg with the blackbox, but a high flow of air. Its meant more for a spoilboard system.

What you want is a low volume, high pressure vacuum system, like a rotary vane vacuum. You want to pull 25"hg at maybe 10-20cfm. The seal on your vacuum pods lets you achieve this kind of vacuum.

The reason you need a higher vacuum pressure is because the surface area of the pods is so small. Even at 25" hg, you are getting only about 12psi of pressure from the atmosphere pushing down on the pod surface area. So if the area inside your pod seal is 5" x 5", you will be getting 300lbs of pressure pushing down on each pod.

With the blackbox, you would only be getting around 4psi, or 100lbs of pressure pushing down on each pod.

When you are cutting with the blackbox and your whole spoilboard, you are getting 4psi over the whole surface of your workpiece. So if you have a 24" square piece of plywood, you are getting 2300lbs of pressure pushing down on it.

[rcrawford]

But to answer your original question, I would have the vacuum going to each pod with a small tube with valves on each tube, and have the pods just fasten down to the T-slot system on your table.

[rcnewcomb]

You can make the pods out of thick plastic. Use AllStar gasket material.

We found a used GAST pump that worked quite well with the vacuum pucks.