Replies to This Discussion

Permalink Reply by Diane in Chicago on January 5, 2011 at 1:36am

I built an acoustic on a 1/4" thick box, and it was really, really quiet.  I won't use that thick again unless I am adding a pickup.

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Permalink Reply by Rand Moore on January 5, 2011 at 5:03pm

Here in China, you can get large sheets of thin plywood laminate, which carpenters glue onto the built-in book cases, cupboards and closets when they build-out new flats (condos) or re-furbish old flats. It's actually about 3/16" thin plywood, but it makes for a nice soundboard, and they have several different kinds of woods as the outer laminate. I used some cherry faced laminate and ended flipping it around so the backside was visible as it matched the wood I was using in my side walls of my box better. Look around for a wood supplier that sells wood laminates.

-Rand.

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Permalink Reply by Mister Scott on January 5, 2011 at 5:13pm

Hey Rand, I've been checking out woodcraft.com, and they have decent prices on 1/4" and 3/16" thick maple. They also have larger sheets of Baltic & Finnish Birch plywood... I might try some different builds and see how they compare.

Rand Moore said:

Here in China, you can get large sheets of thin plywood laminate, which carpenters glue onto the built-in book cases, cupboards and closets when they build-out new flats (condos) or re-furbish old flats. It's actually about 3/16" thin plywood, but it makes for a nice soundboard, and they have several different kinds of woods as the outer laminate. I used some cherry faced laminate and ended flipping it around so the backside was visible as it matched the wood I was using in my side walls of my box better. Look around for a wood supplier that sells wood laminates.

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Permalink Reply by Skeesix on January 5, 2011 at 7:10pm

The bigger the top, the thicker you can go. Case in point - pianos use a spruce soundboard that's about 5/16" thick.

I would stick to about 1/8" for guitar sized tops. The type of wood may make a difference too. At a guess, something in the spruce/pine family would be the best vs. a hardwood. On the other hand, Gibson made a lot of nice hollowbody guitars with laminated maple or mahogany tops.

It would be fun to experiment with various species of wood or plywood and thickness and see what you get.

You can hold the wood by the edge and tap in the middle to get an idea of how well it vibrates and what it will sound like before installing.

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Permalink Reply by Mark Bliss on January 5, 2011 at 8:03pm

Thin is definitely the way to go for acoustic properties, but the very best top woods are fragile and a little tricky. I have studied the construction and bracing of vintage and contemporary acoustic guitars, violins etc and the bracing involved is an art in itself.

In my opinion the ideal top woods are only ideal in relation to their design and in an optimized structure, but I doubt worth all the trouble in an improvised instrument such as what you described, especially if you plan to install piezo circuitry and amplify it and/or for the typical neck-through design with solid support under the bridge.

With that in mind, the economics and easy workability makes the laminated ply stuff suggested by Rand attractive for your "experimental" build. They have some nice thin pieces locally here at Micheals craft store and at a store called Hobby Lobby, also a craft store. I would suggest trying a 1/8 or so thick top constructed with that.

If you want to construct your own top out of what we would call "tone wood" there are spruce top sets and such available from Stewmac, Luthiers mercantile, Dick, etc. But these are typically rough sawn pieces in need of much prep and such before being ready for any use. Lower grade sets arent to pricey in general though, and if you are equipped to surface and fit/glue a bookend set together, you could build something nice that way.

Now all that said, how about a chamois stretched over the bowl while wet and allowed to dry/shrink.................

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Permalink Reply by Mister Scott on January 6, 2011 at 1:54pm

Thanks for the info, Mark. I'm not familiar with chamois and its properties... From what I breezed through online, I assume it's like banjo skin? That might work well for the film can banjo I'm planning later on this year; this experimental build, however, is becoming something akin to a modified sitar.

-scott

Mark Bliss said:

Now all that said, how about a chamois stretched over the bowl while wet and allowed to dry/shrink.................

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Permalink Reply by Jon Pruett on January 6, 2011 at 5:26pm

I saw some very cool "low-brow" banjos using wood salad bowls and used drum heads a while back. I just got a drum head to try this with a couple months back and have it in the project list, but I haven't quite figured out mounting yet. Not sure if the drum head would react better to pinching with some sort of strap or gluing and tacking.

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Permalink Reply by Wiley Rutledge on January 7, 2011 at 6:23am

Chamois can be had at the automotive section of China-Mart or an auto shop----sometimes even at the $1 store.  It's used  in drying cars after washing.  It stretches when wet and can be tacked onto the rim of the bowl and will dry stiff and tight if done right.  I've seen bowl and gourd banjo's done with sheepskin or calfskin---like on a Celtic hand drum (www.DavidBeede.com and www.deepcreekstrings.com) and it makes a more mellow sound that the typical "plunk" of the banjo.  As far as thickness of the wood for a top, it depends on the type of wood and the surface you're covering.  A typical thickness for a dulcimer which would probably be about the width of the bowl, would be roughly 1/8th inch, depending on type of wood.  A softer, more evenly grained (spruce, western red cedar, poplar, butternut etc.) should give a brighter sound, but might need some bracing to support the bridge, while heavier, tightly grained hardwood like walnut, cherry, maple etc. would be stronger, but would probably give a more mellow tone.  A lot of the differences depends on type of wood, denseness of the particular piece of wood you're using and maybe how you hold your mouth when making it!!!  I think the main thing is to experiment, innovate and have fun doing it. 

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Permalink Reply by Mark Bliss on January 7, 2011 at 6:46am

Yeah, thats kinda what I was saying, LOL!

My reference to using a chamois was meant as a generic "how about a cheap skin" for a top.

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Permalink Reply by Wiley Rutledge on January 7, 2011 at 10:27am

I tend to be a bit wordy, but when I start something I try to find out ALL I can before I hit the "go" button.  Hadn't thought about using chamois before but I may try it on a mountain banjo.

Mark Bliss said:

Yeah, thats kinda what I was saying, LOL!

My reference to using a chamois was meant as a generic "how about a cheap skin" for a top.

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Permalink Reply by Bob Harrison on January 8, 2011 at 4:29am

Scotty,

I bet formica countertop material would make a fine top, it is .075" in thikness. It would need to be back braced. I'm thinking it would be very bright in sound. Just a thought.

 

Bob

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Permalink Reply by Mad Mike's CBG's on January 11, 2011 at 1:54am

No more than a 1/4" I would say...Good luck....

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