40 - Vacuum Clamping System, страница 17

FEATURE PROJECT

V HOSE x V&" M.I.P. HOSE BARB

Poly Tube connects vacuum system to jig or accessory.

NOTE:

We used a brass hose barb to connect the vacuum system to the air tube. It's not included in basic kit.

Regulator adjusts air

pressure from compressor.

NOTE:

To assemble this vacuum syste m, see page 31 for sources.

NOTE:

To produce a vacuum with our venturi valve, we used a % hp air compressor that supplies / CFM of air. If you use a different venturivalve, ask the manufacturers match it to your compressor.

Foam Backer Rod

It's one thing to establish a vacuum in each of the jigs. But to maintain that vacuum, you have to keep outside air from leaking back in.

BACKERROD. The key to sealing out this air is a V4" dia. strip of foam called backer rod, see photo at right. Typically, it's used to fill gaps or cracks around doors and windows before they're caulked. But it's the perfect

material for sealing air out ofthe vacuum as well.

One reason is the foam has just enough "give" to fit snug in the grooves that are routed in each jig. And even though it's compressed when the vacuum is applied, the foam springs right back.

SOURCES. Backer rod is available from many building supply companies

that provide materials for contractors. (It costs about a penny a foot.) If you can't find it locally, you can order it from a company called Construction Materials by calling (515) 263-9006.

No. 40 ShopNotes 17