[jharvey407]

I used .75 MDF .5 bit cut .375 deep sealed the edges with 2 coats of 50 50 glue and water. surfaced a piece of ultra lite MDF on one side the flipped it and glued it down using the vacs to suck it down with a piece of ply on top of it. Ran the vac for about 2 hrs then let it set over night surfaced the top top open it up and level it. Hope this helps

Thanks, I'll give this a try. I guess my problem was cause by making the squares to small.

I have seen some pictures of plenums with fairly large squares, that have small, maybe .125" grooves milled into the top of the squares.

[jharvey407]

I finished the plumbing for the vac table. I used 2" PVC and 2" hard vacuum hose.

I haven't glued the PVC yet because I feel like there will be some changes before this project is completed, but I did seal it well with silicone tape. When I plug the inlet in the plenum the vac pulls - 7.5" hg. I feel like this isn't going to be adequate, but the first test will tell.

There is a 1/4" hole drilled in the vac box (as per the instructions) so that there is always some cooling air reaching the lower bearings in the vac motors. When I cover this hole the amount of vacuum created increases by about 1/2" hg.

I don't have the test instruments to test the actual airflow, but it's a lot. These two vac motors pull A LOT more air than my 6.5 hp (yeah, right!) shop vac.

I should be receiving the LDF for the spoilboard today. I'm hoping to have the spoilboard mounted and sealed by the end of the day. Then we'll see how much vacuum this setup reads with an empty spoilboard, versus the spoilboard covered in plastic.