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#1
09-26-2019, 02:54 PM
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A few double sides questions...
If someone who builds that style could chime in I'd appreciate it...
What thickness do you make the lams? I was thinking .060 What adhesive do you use? I was thinking epoxy would probably be safest but wondering if titebond would be suitable. What determines wood choice for the inner layer? Complementary looks, or some particular other trait? Can the lams be bent in a sandwich in one go, or must they be bent individually? Thanks... 
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#2
09-26-2019, 04:36 PM
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1) .060 or 1/16" is fine. That was my standard.
2) I like urea formaldehyde, specifically Weldwood Plastic Resin glue. Long open time; dries rock hard; zero creep; not expensive, very strong. Perfect for laminations, which is why it is the kind of glue used for lam beams. 3) Yes. Complementary looks or some other particular trait. 4) I bent one at a time, but give it a try if you are in a hurry. It won't improve how they mate to do them both together. Clamp a lot, starting at the waist--you cannot overdo this. 
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"Still a man hears what he wants to hear, and disregards the rest." --Paul Simon Last edited by Howard Klepper; 09-26-2019 at 10:02 PM.
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#3
09-26-2019, 04:43 PM
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Thanks!
If double bending them won't make them fit better it seems best to not take the risk...
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#4
09-30-2019, 05:19 PM
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I generally take my outer veneer to around .070" and my inner (of the same species or at least similar color to the outer veneer) to .050". The end thickness is essentially the same as Howard's. I just like a little more 'meat' on the outer veneer in the event that I end up needing to sand a bit more on the outside.
As far as adhesives, I've use Titebond, West Systems, and fish glue. All have yielded satisfactory results. And I also always bend one at a time.
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Michael Propsom
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#5
10-01-2019, 01:35 AM
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Thanks,
I went 60 outer 80 inner. Ziricote out, walnut in. The reason I had to do double sides in the first place is that by the time I got the saw marks out of the sides they were .065, too thin for single side comfort. Fortunately the double side approach is appropriate for this project as the client wants to do modern percussive side slapping stuff. A lot of extra work building glueing forms, but hey, now I can do it again...   gave them both a zap with the heat blanket to conform better to each other... big clamps brought them together well... sweet fit...
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#6
10-01-2019, 01:41 AM
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Oops, don’t know how to edit Tapatalk...
  It is pleasing how accurately formed they are...they’re not perfectly flat but pretty close, I’m going to add further strong flat side supports just to get it as flat as I can. Sure would hate to sand through the outer veneer, though I can’t see that happening even as is. Fingers crossed and wish me luck...
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#7
10-01-2019, 08:10 AM
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Wow! How the heck did you make that form so accurately?
I learned how to do this from a Bogdanovich video, and book, and he builds a clamping cauls system that is sort of like kerf lining if ya know what I mean. It bends and conforms to the sides. But yours is a perfect fit.
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#8
10-01-2019, 09:16 AM
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The cutaway side by some miracle just happened to fit perfectly, much to my delight. The non cut side, which should have been much easier, would not, so I did the Bogdanovich method.
But my greater concern was the cut side as I needed to make sure the extension to the neck block was the correct angle to be parallel with the fretboard edge, so I was pretty happy...
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#9
10-01-2019, 12:51 PM
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Quote:
Other than the modern/percussive style, what would influence someone to utilize double/laminated sides? I seem to remember them being used for classical guitars? Seems counterintuitive to me.
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#10
10-01-2019, 01:25 PM
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Quote:
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#11
10-01-2019, 01:32 PM
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It really depends on the overall intention of the guitar.
The concept is that with single sides, energy from the top bleeds out through the sides via damping, whereas double/laminated sides will redirect more of that energy back into the top to produce sound. A glance through build threads in the custom shop will show a plethora of top builders using them, and certainly they play a part in the more 'modern' voice of such instruments...amongst other things.
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#13
10-01-2019, 02:23 PM
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Those books are worth every penny and more...
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#14
10-01-2019, 03:35 PM
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Quote:
I found the interview I remembered. Michael Bashkin’s Luthier on Luthier podcast did an interview with Mr. Gore where he discussed the experiments of adding (removable) mass to the sides and measuring the frequency response of the top. Of course he discussed any number of other things as well but it was bolting weights to an experimental guitar that I remembered. I’ve got just enough noise/vibration/harshness engineering background to follow the discussions. It’s been too long since engineering school to do the math, I’m sure. 😀
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#15
10-01-2019, 03:42 PM
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Yes, Trevor’s method involves gluing blocks with threaded inserts to the sides for the purpose of adding weight to lower the main top freq to a target number.
His falcate bracing is capped with CF, so unlike normal bracing where you can scritch away at it until it’s just right, he adds mass to the sides...
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