Gluing up plywood from veneer.

[Joe Hillmann]

I need some help on how to make my own plywood. I made a few small samples by using two layers of veneer and gluing them together with contact cement and using a vacuum table to clamp them together. The problem is once I start making the pieces bigger than about 12"x12" I start getting bubbles and ripples in the finished plywood and I need 18"x32" sheets. Can anyone suggest ways to prevent the bubbles and ripples?

[Mel Fulks]

Joe,if its for the doll houses you might try Italian bending ply.Its three lams of poplar making a product just under one eighth inch. But I wouldn't use contact cement.

[Joe Hillmann]

It is for the doll houses, but it has to .055" thick which is why I am making my own. I called up a local plywood factory and the sales guy said since they have a warehouse full of of slower selling products or culls that it would be best if I come out with a micrometer and just start measuring stuff and if I can't find what I need they can custom make it for me. Which is really nice of them but I am worried what the cost of custom making a few sheets would be, which is why I am trying to make my own. (I do plan to head over there next week)

[Jamie Buxton]

A vacuum press is just about the best way to do anything with veneer. It applies pressure everywhere, which is exactly what you need with thin floppy stuff like veneer. You also get to use adhesive which will not fail from the solvents in some finishes.

If you don't want to buy a press, you might well find people on this forum who have a press, and who'd be willing to make you some plywood.

[Richard Coers]

Are you using water based, or solvent based contact cement? Personally, I wouldn't use either, but the water based is going to swell the veneer. Then since it is stuck on the contact cement, it probably won't dry equally. I would use a cold press glue, or unibond. Use platens of melamine stock to keep it flat in the press. There is just enough info floating around that people still swear by contact cement for veneer. It is the last choice of adhesive that I would use.

[Joe Hillmann]

Richard,
I am using solvent based cement. I had that and titebond on hand and I know titebond would swell and bow the veneer like crazy so that is why I tried contact cement.

How much clamping pressure is needed to hold the veneers together for gluing?

[Frank Drew]

...[some] people still swear by contact cement for veneer. It is the last choice of adhesive that I would use.

I agree with Richard; there are a number of glues more suitable for veneering. White or yellow glue worked fine for me on smaller jobs, Weldwood's Plastic Resin Glue for more involved assemblies.

Also, rather than a two veneer layup, I'd do 3 or 5 or 7 plies, changing grain direction each layer; the central ply can be thicker than the others if that helps get to your desired thickness, then balance things by using the same material with each successive bottom and top plies, finishing with your outer layers of similar material.

[Chris Padilla]

Visit joewoodworker.com and learn up in regards to veneering...all of it will apply to making your own plywood as well. They sell a glue there call Better Bonds that dries nice and hard and is easy to use and works very well with a vacuum press, which is the way to go for veneering. As Jamie said, it applies pressure everywhere and just as importantly, it applies uniform pressure everywhere. The Better Bonds only need 12-15 psi. In vacuum talk, normally measured in inHg (inches of mercury), that would be 24-30 inHg. I have my vacuum pump set to 25-26 inHg and it works great. Titebond sells Cold Press Veneer glue but they want you to apply 250 psi!!!

Yes, I agree with the others: do not use contact cement for veneering!!

[Jeff Duncan]

Not sure if it was mentioned before but don"t use contact cement:D Unless of course you gluing laminate, otherwise plain ole' yellow glue will work fine. In the vacuum press I've used Titebond Cold Press on veneer and it also works well. Heck there's probably a bunch of glues that will work well. The only one I would never try is contact cement.

good luck,
JeffD

[Mel Fulks]

Joe, I don't work with thousandths very often ,so I got out some feeler gauges and a piece of the Italian Bending Ply. It looks to me that it could be sanded in a wide belt machine to two equal lams in opposing directions. It is a very well glued material that I have never seen come apart .The glue is invisible ,indeed light comes thru it. Unless you can't use poplar it would be a cheap solution.

[Howard Acheson]

I need some help on how to make my own plywood. I made a few small samples by using two layers of veneer and gluing them together with contact cement and using a vacuum table to clamp them together.

Contact cement is not a good choice for gluing up laminations. You will not end up with a flat end result. Vacuums do not produce much in the way of pressure. If you could create a "perfect" vacuum, the pressure would only be 14 psi which will not produce a flat glue up.

Second, plywood is always glued up from a odd number of plies. If you don't do that, the resulting plywood will not have its forces evenly balanced and it will warp and crack.

[Frank Drew]

Vacuums do not produce much in the way of pressure. If you could create a "perfect" vacuum, the pressure would only be 14 psi which will not produce a flat glue up.

In my experience, vacuum pressing produces exceptionally flat glue ups; vacuum pressing, IMO, is vastly superior to any arrangement of shop clamps and cauls, in addition to being ever so much easier and convenient to carry out. Don't focus too much on the seemingly low number 14 (which is the theoretical maximum psi you can get with a vacuum setup), think of it rather in terms of what that works out to -- over a ton of pressure per square foot! And very importantly, as Chris notes, that pressure is distributed perfectly evenly over the entire surface of your work.

Don't forget, we're talking veneering here, not gluing up a 4" thick benchtop; the pressing method only needs enough pressure to bring the veneer into intimate contact with the substrate while the glue sets up, you just don't need all that much pressure. For example, hammer veneering is a method that's worked fine for centuries, and that relies on just arm strength?

[Mel Fulks]

I think we don't have enough information. As thin as he wants the glue up to be multiple lams are not an option. Why can't the Italian bending ply be sanded and used?

[Jeff Duncan]

I don't think it will be all that easy to get an even thickness by sanding the veneer down? If his thickness really needs to be .055, (just under 1/16"), then he either needs a single layer of thick veneer, which shouldn't be hard to come by. Or 2 thin layers of veneer. Luckily veneer comes in all different thicknesses so he does have some choices.

Also I agree with Frank, contrary to some opinions that vacuum pressing does not offer enough pressure to glue up certain situations, I can assure you that it does! I've had guys tell me on another forum I can't use the vac for gluing up solid wood as it does not provide enough pressure. Yet having done the comparison myself in making passage door stiles, I can get perfect glue lines with the vac press and OK lines by using my entire rack of clamps. Further for gluing thin veneers flat you wouldn't even need to come anywhere near the max vacuum for a press. I would turn my vac down quite a bit for that type of work.

good luck,
JeffD

[Joe Hillmann]

The vacuum table I have is a not a vacuum press. It is a vacuum table that flows a lot of air but at a fairly low pressure drop. It is meant to hold down a piece of bowed plywood securely so I can cut it in the laser and continue holding the plywood even after the laser has cut hundreds of holes in it which is why I rely more on lots of air flow rather than lots of pressure drop. With that said I don't know if it will be able to provide enough pressure to clamp the veneer, although if it doesn't I can try swapping the blower out with a shopvac to get more pressure.

As of about ten minutes ago I am out of veneer so I can't do any more playing/testing til next week.

When it comes to thickness, .055 isn't quite necessary it could be as thin as .049 or as thick as .57 before it starts becoming an issue.

As far as the Italian bending ply and the wide belt sander, where would I go to try and find some to do a test run? My biggest concern with it would be if the laser can cut it. Some glues used in plywood do not play well with lasers.

[Mel Fulks]

With the material on top of a platen it can be ,and has been ,done with a wide belt sander. Every one doesn't own one but it could be easily sourced out. The newer sanders can do real precise work ,that's why the veneer on plywood and MDF are so extremely thin. I have used some older sanders to do jobs similar to what op needs. The material I suggested is cheap enuf that if some pieces are spoiled it would not be a big deal. We do know that it would be used in a doll house so I believe there must be some leeway.But we don't really know much about requirements,I wish Joe success with this unusual task.

[Mel Fulks]

Joe,it can be bought in small pieces mail order.The 4x8 can be bought at most places selling cabinet materials. I don't know what it is glued with but it is thin and invisible,not at all like the thick brown layer of glue commonly seen in plywood.

[Tony Joyce]

Here is a link to a 3/64"(.0468") 2 ply material in most any species.

http://www.tapeease.com/nblwood.htm

Tony

[Joe Hillmann]

If you guys take a look at this link it shows you what I plan to use it for.

http://www.sawmillcreek.org/showthread.php?199350-Dollhouse-critique

And

http://www.sawmillcreek.org/showthread.php?199464-Another-dollhouse

The first link shows a dollhouse made of .11 plywood and .027 veneer I am looking for .055 so I can make a third one that is half the size of the big one and twice the size of the small one.

The thickness of the ply has to be pretty accurate. The kerf on the laser is about .0025 on each side which means I have about .005 to play with when it comes to the tabs fitting into the slots.


Edit: After looking at the links I realized it may be hard to figure out exactly which pictures I am talking about so here they are.
255478255479

[Frank Drew]

Bending ply, by definition, is stiff in only one direction, if that's a consideration.

[Joe Hillmann]

Frank for such small pieces I don't think it will matter.

[Mel Fulks]

Joe I'm sure you agree this project is not worth injuring even ONE doll!! Let's call the material DOLL WALL.