Quick help needed--veneering ?

[Phil Winn]

I am planning on doing this tonight--any problems with it?
1. Using Unibond 800..glue 1/42" Figured Eucalyptus to 1/4" poplar
2. glue 1/42" Figured Eucalyptus to 1/4" poplar
3. glue 1/42" Figured Eucalyptus to 1/4" poplar
4. glue 1/42" Figured Eucalyptus to 1/4" poplar
5. glue 1/42" Figured Eucalyptus to 1/4" poplar
6. glue 1/42" Figured Eucalyptus to 1/4" poplar
7. stack all "5" (five) Figured Eucalyptus/Unibond800/poplar sandwitches together.I may use some wax paper so they don't stick together.
8. Everything goes a 3/4" MDF sheet and under a 1/2" sheet of MDF, then into a 4' x 8' poly bag--with evac net.....
9. Turn Vac on
10. 8 hours.
11. take out.
Questions:
1. Do I need to put 1/2" MDF sheets between each Figured Eucalyptus/Unibond800/poplar sandwitches-OR
only on the MDF bottom and the MDF top?
2. OR should I put in each Figured Eucalyptus/Unibond800/poplar sandwitch in individually between the
1/2" MDF bottom and the 1/2" MDF top sheet?
**Please don't ask why I am doing this....**
Thanks,
Phil

[Jamie Buxton]

The problem with stacking the sandwiches is that they may not stack nicely. As the bag squishes together, the sandwiches may slide around. If one sandwich slides off another, the periphery of the sandwich will not be getting clamped. DAMHIKT:(

You have a giant bag. Why are you stacking the sandwiches? What I'd do is the following... I'd use that 3/4" MDF sheet as a platen. I'd put a sheet of poly film on it to keep the sandwiches from gluing to it. (Poly film... the plastic sheet sold as drop cloth in the paint section of your local borg.) I'd apply the glue to each poplar substrate, then put the veneer on top. I'd flip each veneer/substate sandwich over, and put it down on the platen veneer-side down. I'd spread the sandwiches out so they are not stacked on top of each other. Then I'd slide the platen plus sandwiches into the bag, pump it down, and wait for the unibond to cure.

[John Lucas]

Phil,
What I dont see in your setup is veneer on the back of the panels. You dont need touse good veneer, but a cheap veneer here will keep the sandwich more stable.
I dont have problem with your assemby except that there might be too much exacting work to do to keep the whole stack together. If they start to slip and slide all of your efficiencies will be lost.
Try using blue painters tape to keep things where they belong. Do use plastic between layers of the sandwich and 3) suck down the stack slowly.

[John Miliunas]

There is merit to what both, Jamie and John have stated. With a bag that big, I'd go seperate with each unit, just to be on the safe side. However, John's point on veneering the opposite side is absolutely, positively critical to ensure that your final product does not cup or warp, especially on that thinner substrate! :) :cool: