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Vacuum Veneering

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2K views 6 replies 6 participants last post by  kolwdwrkr 
#1 · (Edited by Moderator)
I haven't had much experience with vacuum veneering large panels simply because you can pretty much buy whatever you want, which is what I have always done. On smaller projects, such as my marquetry projects, I have always glued my veneer to my substrate (one on front, and one of back for stabilization) and then put a caul on the front and back as well. Then placed it into the bag. The question is do you use a caul on larger panels. The caul would be the same size as the panel being veneered.
The reason I ask is because I am working for a company that uses bamboo. We have to veneer one side of the bamboo to match the interiors if they aren't glass. The interiors are prefinished maple. So I had to veneer a few panels with maple veneer. I put glue on the material, spread it out equally, and then taped the veneer to it. I then placed some plastic on it, then a caul the same size. The plastic was to protect the caul from sticking to the piece. I put the piece into the bag and let it run. I took it out after a few hours and there was wrinkles. So I tried again, and the same thing. Is it the caul? How do you all veneer in a vacuum press? Is there a tutorial here somewhere? Thanks
 
#2 ·
Don't use the plastic, if it wrinkles the veneer will wrinkle with it. Use 1/4 or 1/2 melamine, wax it good and it will not stick to the veneer if the glue rises. If you still think you need to cover it with something use brown craft paper it will not wrinkle like plastic will.
 
#3 ·
I use a melamine substrate with kerfs cut into lt to make a "chessboard"........the kerfs allow the air to escape and the melamine wont stick to glue being squeezed out. That goes into the bottom of the bag…...then place the piece being veneered into the bag. I dont use a caul, just the bag and by using a PL roller I can flatten the veneer to remove wrinkles by squeezing out any trapped air and I can see through the clear vacumn bag
 
#4 ·
Keith: I didn't like the idea of cutting a caul to the size of my panels every time I wanted to do some veneering. So I did something very unique I do my veneering upside down.

I have a 4 X 8' piece of melamine in the bottom of the bag. It has saw slices every 6" to allow the air to move around. The hose from the vacuum pump goes through the bag into a hole in the side of the melamine panel and then has a hole from the edge to the vertical hole. That allows the vacuum to get to the slots.

As to the upside down veneering, I make a caul that is a lot bigger than my panel and I put Butcher paper over the caul. It is taped on the opposite side. The butcher paper has a plastic coating and the glue that comes through the veneer doesn't stick to the paper.

So what I do is put my glue on the plywood or whatever I'm veneering. I put the veneer on the butcher paper upside down. The face is against the butcher paper surface. I then put my glued pane on top of the veneer. So what I'm getting is the panel acts as the caul and the larger butcher papered sheet does not flex when the veneer is active.

This keeps a caul from bending under a vacuum pressure if its too large for the panel being covered.

I only veneer on one side this way after It is glued I do the same for the backer veneer.
 
#7 ·
Okay, so the mistake was #1- I used plastic, which could have caused air pockets and allowed the veneer to wrinkle #2- I'm positive I used to much glue, #3- my platen (I called a call, but am learning otherwise) was to thin and should have been kerfed like the bottom platen. I noticed on joewoodworker.com (thanks for the link Dan) that they do use 2 platens, one on top and one on bottom. It shoes both platens at 3/4" thick, both with kerfs to allow air flow. However, It shows that the kerfs on both pieces are facing the bag. I believe in the set up instructions to the press that the bottom platen has the kerfs facing the piece. So that is something new.
I think I will leave the platen off for the next try, as well as look into that EvacuNet. With everyones help I'm sure this will all smooth over and work out peachy. Thanks guys.
 
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