Tips, Tricks, Suggestion, Experience making laminated plates?

[Randolph Rhett]

I missed Chris’ post when he added it. Very helpful. One question though, THREe layers of the 2ply veneer AND a show layer? So seven actual layers of veneer?

[Chris Walsh]

Randolph...right! I found two layers of two-ply and a face veneer to be pretty unstable...but depending what you're constructing...it could work I suppose.

[Brian Evans]

When I toured Benedetto's a few weeks ago they showed me their setup for laminating their plates. They use hydraulic shop presses, for all the world identical to my 20 ton shop press, with male and female molds. Their plates are three ply, 3/16" thick, three layers of 1/16th thick veneer. FWIW a 20 ton shop press costs less than most vacuum setups I would imagine, carving the molds (which looked like quite thick billets of hardwood in metal cradles) would be the hard part. But they have CNC or copy routers to carve their molds. Their outer laminates are highly figured, one piece of beautiful maple. We discussed the difference to my 1946 Epiphone which has 5 layers and was hydraulically pressed.

Brian

[Mark Parker]

I know this thread is a year old, but I thought I'd try reviving it instead of starting a new one. I believe it is Grez who laminates tops with all spruce all running in the same direction. He laminates two sets of two veneers flat, then puts the fifth veneer between them (with glue on both sides) and presses them into the archtop shape. I was thinking of doing two sets of two layers @90* flat and then adding the middle layer (maybe nomex?) and pressing to the arch. I would think that the cross hatch lamination would help prevent the buckling on the lower bout that seems to be such a problem. Has anyone tried this? Or similar?

[Mark Parker]

Well, I tried the cross lamination flat and then pull to the arch form with next lamination and it did NOT work. I used West System epoxy and the double ply was too stiff to pull down to the arch form - at least with my vacuum bag system. Ruined a nice piece of crotch walnut as I couldn't see that the top had not pulled down all the way until I took it out of the bag. By then the center section was glued very securely and the edges were 'floating' pretty much all the way around.
So, unless you have a 20 ton press, don't try laminating first and then pulling down.

[David King]

If you were to use a water based glue such as a PVA, I wonder if you could pre spray the pre-laminated panels with something like a veneer softener product. Perhaps there's a way to add a heating blanket between your bottom convex mold and the stack of laminations to help with forming.
Another possibility would be to use an outside (concave mold) in the vacuum bag where you could determine if the center is sucked all the way down and then help it along with a plunger and/or or a heat gun if it isn't. At least your edges would all be tight even if you didn't get the full belly height.

Another option besides the 20 ton press would be a lifting bladder which can be used with compressed air or hydraulic pump to push the belly all the way down. You would need a rugged press frame for this capable of handling your PSI x square inches of bladder area.

[Barry Daniels]

Wood just does not stretch any measurable amount. It will flex but that is all. There are methods listed on this forum that describe successful ways to laminate arched plates.

[Mark Parker]

I had reservations about the recommendation to leave an 1/8" pie at the bottom 6", but I tried it on an internal layer. It did not close completely. What I finally did for my top was leave the bottom 6" of the maple center stripe untaped. I then did a dry run in the vacuum bag. Sure enough, the maple overlapped the walnut where it wasn't taped. I was able to take it out and with a fine veneer saw trim the walnut where it was overlapped on both sides of the maple. Using the inside of my 4 layer layup as a 'dish'. I pulled the maple and walnut together and taped it with blue tape (the slightly stretchy stuff from Veneersupplies,com is great.) I then flipped it over, used the outside of my layup as a form and appleid veneer tape to the outside. Remove the blue tape, apply glue (I have had better results with Gorilla (PU) glue than epoxy - just roll it out REAL thin.), and back into the vacuum bag. The result, a nice top with no wrinkles.

[Barry Daniels]

Gorilla glue, really? I hate that stuff. Did it foam up on you?

Glad you got the lower dart figured out. How wide of a piece did you cut out?

[Mark Parker]

I, too, hated the stuff until I learned how to use it. If you spread Gorilla glue REAL thin, it doesn't foam. According to one 'authority' I read, it expands ~3x which is why it is great for nomex, it climbs the walls of the honeycomb just a bit to create nice filets. i use a rubber veneer glue roller (https://www.veneersupplies.com/products ... oller.html) and roll it out just as flat as I can. It really uses amazingly little glue. So far, I have had excellent results on veneer to veneer as well as veneer to nomex. It does not have a very long open time, so I just do one lamination at a time, but I can pull it out in 90' and add another layer before going back in the press. Eventually I leave it all overnight which I'm sure is overkill, but it is easy.
Oh, I cut the darts as they arranged themselves on the dry run, ~5" long tapering from 0 to ~1/16 on each side of center stripe.
I just got a really beautiful piece of curly walnut with a very nice crown pattern. It is large enough to do the whole top from the single piece, but how to manage the complex bends?? I think I will try using SuperSoft-2 to saturate it and then press it to the arch mold. If it takes the shape without splitting, I'll laminate it up as soon as it is close to dry. Gorilla glue likes little moisture anyway, but i don't know about the SuperSoft-2. I can tell you it melts shellac and the glue on veneer tape. (Don't ask, bad experience), but maybe just a little residual dampness to keep things flexible would be OK. Anyone with any experience with this?

[Barry Daniels]

I've used SuperSoft-1 and 2 quite a few times. It will make veneer fairly flexible but as I said above, it does not allow the veneer to stretch so I don't think you will ever be able to get a one piece veneer to conform to the arch without using a dart.

I usually follow the directions for the SS-2 and let the veneer completely dry before glueing or bending it. I would be cautious about trying to glue veneer before it is dry. I did some testing once and found that wet or damp wood leads to glue failure in most cases.

That is very interesting about the Gorilla Glue. I will have to give it another try.

I have never used Nomex. How does that change a plate compared to all wood veneer layers?

[Mark Parker]

I have never used Nomex. How does that change a plate compared to all wood veneer layers?

As you probably know, nomex is a honeycomb structure that when incorporated into a guitar top is both very rigid and very light (it is, after all, 90+% air). There are a variety of ways of using it in a guitar top. Some just use a full layer of nomex between layers of veneer. Others use a layer of .06 veneer in the center (sound hole and bridge of flat top) with nomex n the sides. What I am doing is using nomex for the area inside the recurve. i start with a flat .02 veneer and laminate a combo of veneer outside (~2") where the recurve would be with a center of nomex. Once that is laminated, I sand the edges of the nomex from .06 to the .02 veneer and use some epoxy to be sure the border is stable. Then I laminate .02 veneers on top for a total of 5 layers so it is .100 on the edge and .140 in the center. I am hoping this will mimic the thinner area of the recurve and the thicker center on a carved top, but since this is my first guitar, I cannot tell you that it works!

[Clay Schaeffer]

Does anyone layup the halves of the plates separately and then joint and glue them up like you would a flat top back or soundboard? I wonder if that would allow the veneer to be molded without darts?

[Mark Parker]

I would think that very difficult to joint complex molded pieces and would take away the strength you get from cross grain lay-up.
FWIW, I just successfully molded a single wide piece of "cathedral" grain curly walnut into an arch. I used SuperSoft-2 to saturate the veneer, then placed it on my form with a couple layers of newsprint on each side and then slowly pulled a vacuum while "massaging" the wood. I know others have said it cannot be done, but my piece took the compound bends without cracking. It is scary taking a gorgeous piece of wood and knowing you may ruin it, but maybe I was just lucky. Your mileage may vary.
Just a note: I did this with the veneer by itself. Once it was formed and dry, I glued it to the other sheets in the lay-up. That way, if it didn't work, I didn't ruin all 5 layers.

[Clay Schaeffer]

Hi Mark,
I'm thinking the strength would be similar to that of a carved solid wood plate, not as strong as a plywood plate, but maybe strong enough. Jointing and gluing the edge might be a little tricky. I'm still at the "musing" stage, and researching what other peoples experiences have been.

[Barry Daniels]

Mark, congrats on your success with forming the veneer. I didn't think it could be done. You may have come up with a completely new technique. May I ask, how high of an arch do you have in your plate?

[Mark Parker]

May I ask, how high of an arch do you have in your plate?

About 5/8" at max (around the bridge location) FWIW, it is a 17" lower bout.