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As an experiment I'm thinking about doing a guitar with 2 tops. Yup, 2 tops...
Not the common style using nomex... I'm thinking about gluing a redwood top to a spruce top at about .060 each and just glue them together and see what happens.
I have seen cheap guitars with laminated tops that sounded ok, so would this work at all?
Anyone here seen or done anything like it??

Well, i may just do that!

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Peter, i'm in no way an expert but i have built my first using oak ply which sounded... well, ok if you will but would never compare to a single top out of spruce or out of redwood for thyat matter, knowing what i know now, i would not recommend this to you at all especially when i think about all the glue that will be between those 2 plates. If i were to do something like that, it would be for the sides only to gain more solidity or rather stiffness. Again, i'm no expert and could be wrong so i'll wait and see what others have to say on this, hope this helps!

Read this....


Hahhaaha!! I just did a search for this forum in the archives, and one of your customers posted in it today!!!

Love new ideas...

I've done a bit o' research, and most of the stuff I come up with has a honeycomb layer instead of a thin layer of solid wood.

I am no expert, but if you cross-grain the tops, it'll end up being like a 2 ply lam, with the stiffness of a laminated top..

How about the two layers, with exposed parts of the top layer soundboard ...say for example in the lower bout?


But...if the grains run together, with lighter bracing... I wonder....???Sam Price38987.8737152778

Cool that is Sam!

[QUOTE=Sam Price]

But...if the grains run together, with lighter bracing... I wonder....???[/QUOTE]

Sam, thats exactly what I have in mind....peterm38987.8740856481

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Peter,
It sounds like a good idea to me. One key will be the ability to get enough pressure on it to create a decent joint with an even layer of glue across the entire joint.
I think I would try it with LMI glue. Maybe you could make strong flat plates by bonding a couple 3/4" birch plywood sheets together. Place the laminate between a couple of plates and drive your truck on it so the wheel is in the center of the plate. (No, I'm not kidding.)
If your cars weighs 4000lbs and your plates are 18 X 22 that will give you only 2.5lbs/sq in of pressure. For wood glues 25 - 50 lbs/in sq is often recommended.
Can you find a big press to use?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Wow Steve....

I was thinking gobars??

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Curious, I read the attachment comments over at the other forum and those here. What is the purpose? Are you not happy with the single tops construction? What do you hope to achieve or what is the objective in doing this?

Mike
White Oak, Texas

[QUOTE=SteveS] Peter,
It sounds like a good idea to me. One key will be the ability to get enough pressure on it to create a decent joint with an even layer of glue across the entire joint.
I think I would try it with LMI glue. Maybe you could make strong flat plates by bonding a couple 3/4" birch plywood sheets together. Place the laminate between a couple of plates and drive your truck on it so the wheel is in the center of the plate. (No, I'm not kidding.)
If your cars weighs 4000lbs and your plates are 18 X 22 that will give you only 2.5lbs/sq in of pressure. For wood glues 25 - 50 lbs/in sq is often recommended.
Can you find a big press to use?[/QUOTE]

This is actually not enough pressure. Your tires only have 30-35 psi in them and the contact area of the tire is much much smaller than the area of the top, maybe 6X8 or 48 sq inches vs. 20X16 or 320 sq inches for a guitar top.

Sam, if you run the grain across like that it'll for sure warp the sound board. You need 3 plies to keep the laminate balanced. 0,90,0 would work.

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Jim Watts
http://jameswattsguitars.com

Now I'm getting confused!

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

[QUOTE=MSpencer] Curious, I read the attachment comments over at the other forum and those here. What is the purpose? Are you not happy with the single tops construction? What do you hope to achieve or what is the objective in doing this?

Mike
White Oak, Texas[/QUOTE]

Mike, new tecniques and methods are found by experimenting new things and learning through them. I want to see what kind of sound you'd get from 2 different woods reacting together on a guitar. Does that make sense? well, we'll soon find out!

Obviuosly, any input is good and if someone else already tried it, then we'll know the results and have an idea of what it would sound like and if it EVEN worked!peterm38988.0014930556

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Peter,
I would suggest vacuum clamping for the gluing process - it would be the
ideal method as it is the de facto method for the veneer industry.

However, I might be one of the few folks who doesn't see much of a
structural advantage to what you are trying to do - but I also don't see a
disadvantage either. I would advise against using lighter bracing than
you would for some really stiff spruce. It seems to me that the top won't
be much stronger than a solid piece of wood would be. I certainly don't
think it would be stronger than a great piece of Adirondack. Then again,
you might be able to produce a soundboard that will be a true tonal
hybrid - which could be very cool.

I look at it like taking a mahogany neck and slicing it in sections and then
gluing them all back together. Your end product isn't going to be much
different than your original product. When I build my necks, I do cut
them in half and flip the grain orientation and glue back together because
I believe it makes the necks more stable and more resistant to warping.
So it is possible that the way you orient the grain could give you some
benefits.

My personal opinion would be to experiment with a double-top ala
Charlex Fox's Ergo - with the honeycomb sandwhich inbetween two thin
pieces of soundboard. I personally see a much greater structural benefit
to that sort of system and you could go way light with the bracing. And
you are basically going thru the same process anyway, so it wouldn't be
much more work.      

Regardless, it seems like a really interesting idea. Although, the sinker
redwood is such a cool tonewood, I would hate to see it hybridized. But
please keep us all posted on how it turns out. It is late so I apologize for
the disjointed writing.

God bless friend,
SimonSimonF38988.0328356481

While I don't really see what you would accomplish with this i can see the mad scientist approach and say why not.. Like Simon, I would say the only clamping method I would consider would be vacuum and I would do it in a radious dish with a radious insert. My recomendation for glue would be Weldwood, strong, doesn't creap, plenty of working time and dries crystaline like HHG. Use a roller to get it thin and even. It also is resistant to heat so you would have less chance of a delamination when you forget it in the car.. My 2cents.
Mike

Thanks for all the input... the only thing I hadn't put much thought in was in the gluing process. I was thinking about using Titebond II which is a more heat resisting glue than regular titebond or LMI white.

So you guys don't think go-bars would work? Don't have vaccuum available at the time...

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Peter,

I have an Alverez Artist series taht has a laminated top. Very near the top of my "too do" list is to take the top off and replace it with a one piece top. I tink that you will find that no one that builds lots of quality guitars would ever recommend laminating two pieces, of any species, the same or different, together. I think that Serge hit part of it, the glue itself will interupt the woods reactions but probably more important from my intuition is that you want a top that is light and responsive but structurally strong enough to withsatnd the tension of the strings. Laminating gives you the strength but IMHO robs the acoustic potential you are looking for. Just my opinion, not worth much...BUT if you try it we will all know when you report back to us.

Good Luck my friend.

Shane

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Canada

Shane, thanks for the input. I once had a Yamaha guitar and I din't know it had a laminated top until faith revelead it to me when someone stepped on it!! Amazing!!! It was a laminated top...pretty crappy I may add but nonetheless it sounded great! So if a laminated top made out of a spruce veneer glued onto who knows what can deliver a decent tone, what would prevent two great pieces of wood from delivering an even better sound??
I guess I'll have to sacrifice two nice tops to find out. Worst case scenario I start over with one top!!
peterm38988.1121875

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

BTW, does anyone have the tutorial on building a two-top guitar with Nomex? I saw an article on the Guitar Maker magazine (if I'm not wrong) and it showed the process.
I would like to see that or any other info on using nomex...

Thanks

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Don't do it Peter! It's Evil! No good can come of it!

   I love experimenting! What you want are really good, or surprizingly, really bad results. They both can tell you a lot. I believe when top nomex laminations are done, they are usually done with a vacuum(like veneer).

      Go bar, or the girlfriends Neon, are to point specific. Besides they might get to like driving on guitars if you get the drift!

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

[QUOTE=Shane Neifer] Peter,
...you want a top that is light and responsive but structurally strong enough to withsatnd the tension of the strings. Laminating gives you the strength...
[/QUOTE]

I don't understand how laminating two pieces of spruce with the grain going in the same direction is going to going to make that top any stronger than a solid top made from the same woods? The main thing you will have added is the mechanical properties (and the sound characteristics) of the glue layer.    

Ordinary plywood guitar tops are great for dimensional stability because of the alternating grain directions, but the top also needs to be thicker than a solid top is along the grain because of the same thing, so it will also be heavier; all this leads to a less responsive, quieter top. The Nomex core tops are different in that the core is a very light material and the skins really thin (in the .6 mm range) so you can end up with a really light but strong top. The strength depends mostly on the thickness of the core which determines the distance between the skins. This is a good recipe for a responsive and loud top, whether you like the sound is another matter. Not really a tutorial, but here are some pictures and thought about it from Randy Reynolds

An interesting secondary soundboard variant is the "Virzi Tone Producer" that was an option on the Gibson arch top mandolins in the early '20's. It is a small spruce disk suspended under the soundboard of these instruments. Most of them have been removed from the original instruments over the years, but some like them because they feel they add complexity to the tone of their instruments even if they are somewhat quieter because of the extra weight. Dudenbostel among others include them on some of his new mandolins.

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Rian Gitar og Mandolin

Take it for what it's worth but for loudness, there are K & K's and other sound devices, i just hate the thought of giving myself more trouble than it is already and also would hate sacrificing a beautiful top that would serve on another nice project.

Don't get me wrong, i'm all for evolution but this is somewhere i would not want to go to, to me, it diminishes the charm of lutherie.

Peter I can post so construction photos later tonight on making a double top with nomex.

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Jim Watts
http://jameswattsguitars.com

Lamination will give you no additional strength.

I assume peterm is talking about gluing both tops with the grain running in the same direction, as is done with other double tops. Cross grain is going to seriously affect the along vs cross grain stiffeness of the top.

Have you seen what Holtier does with his double tops? He does as peterm suggests, gluing two tops together. However, he uses CNC to honeycomb one of the tops, and then glues on a skin.

http://www.holtierluthier.com/models.htm

[QUOTE=Jim_W] Peter I can post so construction photos later tonight on making a double top with nomex.[/QUOTE]

Jim, that would be great!
Thanks

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

The 0/90/0 tri-layer is a pretty good idea. Rather than using a wood glue that requires a lot of pressure to achieve a good bond, you might want to think about using epoxy or even a contact cement if it dies hard. Contact cement is often soft after it dries. If you go that rout be sure to find a product that dries hard.

With epoxy, you could use your go-bar deck.
Look at Loctite's Hysol E30-CL epoxy.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.