Vacuum Plenum cut 

Finally got around to cutting the plenum for the vacuum hold down system for this build.
Basically it's a gridwork cut into the main table surface with through holes, that are plumbed with PVC pipe to a manifold then connected to a vacuum source. This one is separated into four zones, each tied directly to individual shut off valves, then dumped into the manifold. Each zone can be shut off to divert suction to the others.
Larger machines use expensive centrifugal pumps to provide the suction but this one is run by a large shop-vac motor.