Thanks for the comments, guys - glad this might prove useful to you.
The venturi vacuum generator is a really simple device, no internal moving parts. It simply takes compressed air which blows straight through the enclosure, with the vacuum tube placed at the correct location of pressure drop just pas the nozzle inside. If a piece of dust get sucked up by the vacuum port, I assume it would just get blown through. This is why I didn't go with a vacuum pump type assembly - similar to the sets used for veneering.
Most of the venturi vacuum generators can produce a vacuum of about 25 inches Hg. The thing to watch is the air consumption if you have a small compressor. I don't run mine continuously, just when I'm making the cut. I think mine consumes about 4-6 cfm at 90 psi from the compressor. Vacuum is measured in atmospheres or inches of mercury - not psi (pressure). I guess pressure implies pressing on an area... I think Lee Valley uses pressure to put their description in terms we normally work with. I was corrected on the phone while researching this!
It works pretty well, but due to the inclined surface of the stop block - also where the vacuum is applied to the piece - the chip tends to walk up the inclined surface until the blade no longer contacts the chip. This is the reason I put the other toggle clamp above the location of the chip - just to keep it from sliding up along the inclined fact of the stop block.
I will get a PDF together and send it along.
Thanks for the link John - by all means, any ideas are definately worth it! I welcome all ideas since that gives me new ideas too, which is the best part. I'm curious if the Lever Valve of the Lee Valley system is the venturi device, or if the venturi is located in the vacuum base they show. This is the same idea though... Thanks!