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View Full Version : A topsy-turvey idea - laminate top and solid body?



kissing
05-16-2011, 07:04 PM
From reading that other topic, I just got this idea of what would happen if you made an instrument with a laminate top and a solid wood body.

Sounds pretty stupid... but these kinds of things interest me :rolleyes: :confused:

Perhaps it wouldn't be the loudest instrument, but would it produce a different, unique kind of tone that the conventional solid tops or laminate tops do not?

southcoastukes
05-16-2011, 07:51 PM
You'll see this in guitars with double tops (nomex core laminates). Many feel their sound is superior to solid tops - they certainly have more range and volume. As they can't be made thin enough for good results on a ukulele, with us the situation is different.

I don't see any advantage to this arrangement on a ukulele, unless you are looking for less sustain, volume and range.

p.s: we haven't given up on laminate tops altogether. The comparison test mentioned in the other thread was with Western Red Cedar. We are going to tweek our wood/carbon fiber laminate construction a bit, and try it again with a Mahogany top. A hardwood soundboard doesn't have as much flexibility, so maybe this will be where a laminate top will work best.

velofille
05-16-2011, 10:26 PM
Go plywood the whole way! go on! you know you want too! :D

ichadwick
05-17-2011, 12:52 AM
..an instrument with a laminate top and a solid wood body....
The sides and back act mostly as reflectors of the sound produced by the top. The top is the primary sound producer. Sides and back are thicker than the top for structural reasons. The top needs to be thin to be able to flex. Side and back woods are often dense like rosewood (often laminates) because they are more reflective than softer woods. Laminates have an advantage in that they are less flexible than solid woods - their design thwarts lateral movement.

Having solid sides and back would matter very little to the sound of a uke. A little energy would be lost in absorbtion by the energy, but not a lot. The laminate top makes the real difference. But so do the saddle and bridge materials.

southcoastukes
05-17-2011, 04:22 AM
Go plywood the whole way! go on! you know you want too!

Allright, I confess! We've always wanted to build an ukulele that would have no compromise in sound, keep the sound of wood (not knocking the all carbon fiber, but it's a different type of sound), and avoid all the problems with humidification. I hate the idea that people (especially in the colder climates) essentially have to lock up one of our instruments for a good part of the year.

If we were building guitars, we could do it - no problems. Double tops and laminate sides & backs are proven commodities now in the high end instruments, and most people will tell you they like the sound better.

We wouldn't actually have to go all "plywood" in an ukulele. If you're interested, here's where we are now:


http://www.southcoastukes.com/index_files/construct.htm

Bradford
05-17-2011, 07:46 AM
I have been playing around using veneers and liquid hide glue to build ukes. The first soprano I made sounded very good to me. I have started on a concert now. I wonder about the potential for using balsa as a core material. I know that some classical guitar and violin makers have done this with some success. I think the problem with Nomex is it is manufactured in limited thicknesses. That is not an issue with balsa. Something to think about.

Brad

southcoastukes
05-17-2011, 08:23 AM
I wonder about the potential for using balsa as a core material. I know that some classical guitar and violin makers have done this with some success. I think the problem with Nomex is it is manufactured in limited thicknesses. That is not an issue with balsa. Something to think about.

Brad

Brad, that's a great idea - especially for us, as Balsa grows down where we build. We even used to make our shipping boxes out of it until the international wood packaging regulations barred us from using untreated solid woods.

What a great forum!

Also, why hide glue? I know it's a good material for a lot of applications on a musical instrument, but for laminating, have you ever tried urea resins?

Uke Whisperer
05-17-2011, 08:47 AM
Great thread! Very informative! Please keep this one going, who knows what might come out of it!

Bradford
05-17-2011, 09:20 AM
I started my laminating project as a way for hobby builders to take the next step up from a kit. As a one man lutherie shop, laminating for me takes far longer than using solid wood and is probably only something I would only do to screw around. I tried several glues, bleed through was a problem as the veneers I was using are only .022" thick. I found that Titebond liquid hide glue worked great for this. It has a very long working time, it does bleed through, but it is easy to clean up with a damp cloth, and any glue left disappears under the finish. For those interested, see my thread on building a laminated ukulele.

Here are some of my thoughts on this. Currently, I use three laminations of veneer, for a total thickness of .068". I could replace the center lamination with balsa .040" thick. If the balsa weighs 30% of the veneer, the layup would be about 20% lighter. With a total thickness of about .082, the top would be considerably stiffer. I am just starting to build a concert now, I'll use what I just laminated up as the back and try a balsa core lamination for the top.

Brad

southcoastukes
05-17-2011, 09:47 AM
a total thickness of .068". I could replace the center lamination with balsa .040" thick. If the balsa weighs 30% of the veneer, the layup would be about 20% lighter. With a total thickness of about .082, the top would be considerably stiffer. I am just starting to build a concert now, I'll use what I just laminated up as the back and try a balsa core lamination for the top.

I'm sure you'll get done before we will. I'll be very interested to hear how you like it.

I'm a little surprised on the thickness. I'm sure Balsa can be worked down pretty thin - probably as little as 1/32" - maybe less. Omar (our builder) makes some Nomex double tops for his guitars and always stays in the range of a solid top with his thickness.

Also on the glue, we just found that not only were the urea resins easy to work, but the difference in tap tone on our backs was like night and day (though we didn't try hide glue).

Bradford
05-17-2011, 11:38 AM
Thanks for the info on the thickness and glue. With that in mind, I will aim for a little thinner, say around .075". I am looking to stiffen things up a bit, on my laminate soprano, there is quite a bit of top deflection around the bridge. I was thinking that if I built another, I would need to enlarge the bridge patch and/or add a couple of small fan braces. This may be a better solution. Anyway it may be a while for me on this too, I got 4 new orders for custom ukes last week, this kind of experimentation I do in my spare time, which is disappearing fast.

Brad

southcoastukes
05-17-2011, 12:30 PM
Anyway it may be a while for me on this too, ...this kind of experimentation I do in my spare time, which is disappearing fast.
Darn - I was hoping you could sway me in one direction or another. I have carbon fiber in hand for one prototype, but the balsa sounds intriguing. For us it would cost almost nothing, and spare the hassle of another "imported" material. We don't really have time to squeeze in a pair of experiments either, but I might just do it anyway. Oh well, c'est la vie. At any rate, thanks for the inspiration, and I'll let you know how it works out (eventually).

Bradford
05-17-2011, 03:50 PM
OK, why work when you can play! To my surprise I was able to find some 1/16" thick balsa close by, so I have laminated a mahogany-balsa-mahogany sandwich. I thinned the balsa down to .8mm, the other veneers are .6mm, so that will give me a nominal thickness of 2.0mm. We will see how that works.

Brad

southcoastukes
05-17-2011, 05:23 PM
Man, you are fast! With us, it's a partnership stretched across the Gulf & Caribbean. We can't even talk about something as fast as you can do it.

We'll have our regular saturday morning "production chat" and see where it goes from there - although mahogany will almost certainly also be our hardwood.

kissing
05-17-2011, 10:03 PM
I'd never heard of Double Tops til I read this thread. It seems like really interesting and clever stuff!
And it almost seems like it's a matter of time before it can be innovated towards ukes.

Surely if classical guitars benefit from it, a uke can too.
Perhaps the bigger ukes like tenor or baritone?

ichadwick
05-18-2011, 01:12 AM
Balsa would not reflect very well because it's soft. It would need some sort of denser laminate.
Try this: Put some brass foil or very, very thin brass sheets (available at many hobby stores) inside to help reflect the sound. No significant change in weight, but a few strategically placed pieces on the sides or back could really boost the sound. I'm experimenting with metal and foil with my banjo uke's reflector plate and the result in a uke could be very nice. Could add a light resonator-type tone to the output.

Bradford
05-18-2011, 08:28 AM
Ian, in this case the balsa is sanwiched between two pieces of mahogany veneer, so I don't think sound reflection will be a problem. Anyway here is what we have so far. I removed the wood from the laminating jig this morning. The thickness came in right at 2.0mm. Comparing the balsa core lamination to the 3 ply mahogany, the balsa is quite a bit stiffer and is 15% lighter, just what I was aiming for. The tap tones are different, but fairly complex and from my experience should produce a nice sounding instrument. Just how good remains to be seen, but I am hopeful that there may be some benefit to this. After I assembled the laminate and glued it up, I did some reseach online. A couple of ideas surfaced. One would be to punch out some holes in the balsa and fill them with some thin carbon fiber dots, especially in the bridge area. Another idea would be to graduate the thickness of the balsa core, from thin around the edges to thicker in the middle. The balsa is really easy to thin down. That is both the fascination and the frustration of lutherie, there are unlimited things to try. Now I have to go build some ukes, when I actually start construction on this, I'll start another thread in the Luthier's Lounge, I don't want to hijack the thread.

Brad

southcoastukes
05-18-2011, 08:45 AM
I think Ian was talking about backs and sides. Tops need to have that combination of light/stiff, and tops don't need to reflect. Otherwise you'd have rosewood soundboards instead of cedar. The softwood tops generally produce the more volume than the hardwoods.

kissing mentioned adapting nomex for ukes. It is a possibility, but as you mentioned, Brad, it doesn't come thin enough, and although it can be sanded, it's not nearly as easy to thin or shape as the balsa (or as easy to glue, for that matter). It would be a lot more work with no real guarantee that it wouldn't just start to disintegrate when you got it thin enough. Even if you could get it to work, it would be a much more convoluted process than the balsa.

Will look forward to your new thread, Brad.