CDX Plywood

[Rob Davis]

Any great ideas on how to consistently hold down CDX plywood to the vacuum table? I have a fresh cut spoilboard and decent suction. Stuff is just so twisty, not sure if I can consistently hold it flat and I need to do so.
Rob

[Will Williamson]

Try to position the sheet so that edges contact the spoil board first and then take a roll of tape 1" or wider and tape all the way around the edge,then set the vacuum leaver, then turn off dust collection so that tool path is packed with dust. Nothing speedy about this but it works. Try not to let the sheets set around use them fresh from the distributor the more they dry out the more they warp . Worst case senario you have to upgrade to BC grade

[david marcotte]

Rob, Here is what I do. If my stock is on stackers for storage in the shop I lift the material and under the middle stacker I place a 48" piece of material about 4"x4" then I lower the load. Sometimes I weight the ends to keep them down. I also put the next days plywood on a designated table with a 2x4 x 48" placed across the center of the table. I clamp all 4 corners. The next day the wood has a very slight bow but no twisted corners. I place on the vac table the arch is up and the vacuum sucks it down and I have no problems. Plywood left sitting around seems to "potato chip" no matter how flat it is sitting.
Hope this helps, it works for me with laminated particle board, and plywood.
David

[Rob Davis]

Will & David,
Thanks for the suggestions. 3/4" plywood is tough stuff to un-warp once it has moved! We'll try some of these but I have already gone back to the customer saying he needs to upgrade to BC plywood if he wants us to do this. The parts are CNC work so anybody will have the same problem. I also tried a downshear cutter to push sheet onto table and that helped but if I can't get the seal on it, once it starts to outline, the sheet moves.

[Michael S Murray]

Hi Rob,
what we do when we cut plywood for die wall plates and or studs is to set the router to cut halfway through and then we stop the machine and go in and shoot a couple brads into each part, this works well. It does take a couple minutes to snap off the brads, but beats losing a part and having a mess or worse. Dont know if this will work for you, but is a something we sometimes do if needed.