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Suddenly and unexpectedly I need to make a double sided guitar, to salvage a set of ziricote that was cut too thin. SMH.

So for folks that do so...

How thick do you make your lams?

What adhesive do you use?

What determines your wood choice of the inner backup layer?

Usually around .050-.060 outer and .045 innermost.

Normally same wood although a Rosewood inner side on a Maple guitar has provided a nice tone for me and people seem to like it.

Unibond 800. Dries hard like glass.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I would be inclined to use EIR (lower grade or mismatched set) as an inner layer. The radial, tangential, and volumetric shrinkage numbers are not too far different from Ziricote, and it is a similar dark color.
Although I do a fair amount of laminated work, my own peculiar method (relaminating flitch matched veneers back together) limits my experience somewhat.
Many people prefer to use a lower cost wood for the inner plies and cross the grain as in plywood which may have some advantages when laminating dissimilar woods.
I use west system epoxy and dry out the woods just prior to laminating. For open pored woods I think the epoxy is drawn into some of the places the water has left and makes for a more stable lamination. Again, others use different glues and report success with them.
Since the sides have a somewhat serpentine shape a two layer lamination might be O.K., so thicker pieces than typical veneer might work O.K.
Hopefully others will post with their experiences making double sides.

I use Unibond 800 like Terrance. Not only does it dry hard as glass, it doesn't bleed through like West epoxy.

.06/.06 because that's what my sand can comfortably handle.

I laminate on my solid bending mold with vacuum and bag.

I like EIR inner laminates because LMI sells them inexpensively. I tried some port orford cedar, but it wasn't stiff enough for my liking. Would have made an amazing smelling body though...

Hmm, I have no orphaned RW sides. I was thinking of black walnut as I have some...

I picked EIR because the color and "shrinkage" numbers aren't too far out from Ziricote's and it is readily available. Walnut is not as close but it may work fine too. I have an old 1800's parlor guitar that is BRW veneer over spruce and it has held up o.k..

I just bought some lower grade Mahogany from Hibdon for less than $10/set to use for inner lams. Actually looked pretty good.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Ha! I do have a spare set of mahogany sides but they're precious. Getting mahogany in Canada is not as easy as your side of the line.

Any reason not to use the walnut?

I can’t think of one.


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Forward!

Go for it!! Report back. I think you'll like the double side sound if you have not done it before.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Fortunately it’s appropriate for this project as the client is looking for a modern slap and tickle guitar. I would have strongly reinforced the sides with braces anyway.

How do you actually glue the lams together?

Would love to see some pics.

Pretty sure I’m going with epoxy...

Going with epoxy because I have it. Can’t find unibond without having to wait for shipping, will check Windsor’s AM...

If you're using epoxy and an epoxy pore fill, you won't see and bleed though anyway

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

For 2 ply .060 each for 3 ply .060 and 2 .022. T1 glue, weldwood plastic resin glue

I use a vacuum pump and my bending form. I use solid bending forms, so I put some foil over the the form to keep it from getting gunked up with glue. Then I spread the adhesive and use low tack tape to tape the two lams together since they have a tendency to slide around at first. Once that's done, I just put them on the mold, slide it in the vacuum bag, and hit the on switch.

Right. I think I'm going to have to go with the Bogdanovich approach. Sounds like a chess move...

Or fencing . . .

Inigo Montoya: You are using Bonetti’s Defense against me, ah?
Man in Black: I thought it fitting considering the rocky terrain.
Inigo: Naturally, you must suspect me to attack with Capa Ferro?
Man in Black: Naturally, but I find that Thibault cancels out Capa Ferro. Don’t you?
Inigo: Unless the enemy has studied his Agrippa… which I have.

How are you guys prepping these laminates before bending? What are you sanding to and how much more material can one expect to remove when cleaning up after the bend? I ask because going this thin doesn't leave much room for error (sand-through).

It sure doesn't.

I think that's why the solid bending forms or moulds are required, so that when you clamp it, the sandwich gets flat within the range of thickness of the outer side.

By the time my ziricote sides were free of saw marks they were .065...

Naw. It’s really easy. You’re basically put the two lams on the mold and sliding it in the bag. Speed certainly isn’t an issue because the glue has such a long open time.


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Thickness sander has 80 grit. I quickly sand the outer faces to 100 before bending. The two inner faces (the two sides that get the glue) don’t need to be cleaned up at all. You’re not removing enough material to make a difference.


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This is my rig. I shaped the cauls pretty close and then coated them with Durhams Rock Hard putty and pressed them against the form and later added a layer of gasket cork. I use the laminating form as the bending form as well.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

That looks pretty straight forward Terence, is your form solid or with pipes across it?

It is solid but I just drilled holes in it with a forstner bit on the drill press for the clamps. Actually pipes are not a bad idea for strength. The holes have held up OK though. If I ever get a vacuum pump that sounds like a great approach. If you bend the two lams together in the bender they fit perfectly so you really don’t need massive pressure.

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It's not what you don't know that hurts you, it's what you do know that's wrong.