3 or 4 piece backs

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Mark Daigrepont
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3 or 4 piece backs

Post by Mark Daigrepont »

With all the problems (and prices) luthiers are confronting with the standard two piece backs, what advantages/disadvantages would a 3 or 4 piece back have? I've played and read much about Martin's D-35 three piece, and I would think that most people think that the D-35 is a great success. So why don't we see more 3 and 4 piece backs? If it does not affect the tone/sound adversly, wouldn't it be prudent from an ecological and economical standpoint???

Michael Lewis
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Re: 3 or 4 piece backs

Post by Michael Lewis »

One reason you don't see more multiple piece backs is because many of them are well matched for grain pattern. They are out there. The only negative I think of is the bit of work to make the extra joints.

Clay Schaeffer
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Re: 3 or 4 piece backs

Post by Clay Schaeffer »

I have a parlor guitar from the late 1800's with a four piece back. It is only noticeable on close inspection. As long as wide boards are available in desirable species I think 2 piece backs will be the norm. They are less work to make and better accepted.

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G.S. Monroe
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Re: 3 or 4 piece backs

Post by G.S. Monroe »

I've been considering going to a 4 piece back (and top soundboard) for dreadnaught acoustics. I would disagree that wider boards are easier to work with. If you purchase your soundboards, then that may be the case, but I cut and plane my own and there is a limit to what can be made with the shop equipment I have. Unless I spend a few thousand dollars buying a bigger band saw or small sawmill I'm limited to about a 7 inch wide panel (that's a 14" wide book matched board ). I think that the lack of 3 or 4 piece backs have more to do with esthetic appearance than with function though. People have come to expect to see a nicely book matched 2 panel grain pattern on their guitars, anything else and they start questioning the "quality".

Clay Schaeffer
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Re: 3 or 4 piece backs

Post by Clay Schaeffer »

As Michael mentioned, a well matched four piece back can be hard to detect. Also many builders have used "wings" on the lower bout to grow tops and backs for larger guitars. With a 7" panel a 1" wing will get you to a dreadnought size. The wings are often taken from the waist area of the top, and if well joined can be hard to detect.

Michael Lewis
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Re: 3 or 4 piece backs

Post by Michael Lewis »

Clay, the "wings" are standard procedure in many shops. I'm a bit surprised the subject came up, but I can see from the perspective of someone starting out why it did.

Alan Carruth
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Re: 3 or 4 piece backs

Post by Alan Carruth »

As with so many things in this business, people have been indoctrinated a certain way, and anything else is just 'wrong', no matter how logical, or even better, it might be. Frank Ford once told me that the easiest steel string to sell is a Martin, and the further you depart from that, the harder it is to sell. I think there are still folks who look askance on the D-35 because of the three piece back. Martin used it, I believe, to utilize narrower BRW when wide stuff got harder to find, and made all sorts of claims about the 'benefits' to get it to sell. Multiple piece backs are not an issue structurally or acoustically, but we small shop and individual makers are shoveling s(and) against the tide on that.

Mario Proulx
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Re: 3 or 4 piece backs

Post by Mario Proulx »

Actually, Martin did us all a disfavor with the D-35... They braced the top much more lightly than a D-28(they use the 1/4" bracing from the OM or 000, I believe) giving the D-35 a deep bottom end, which can be great, but the vast majority of them are just plain "muddy" and "unfocussed" in tone, which players(the folks who buy our guitars and thereby dictate what we can build) incorrectly attributed to the 3-piece back. This myth was helped along by Martin's own marketing of the D-35 which, at least in the early days of the 35 model, boasted that the 3-piece back was the reason for the deeper bass response.

So now it's all an uphill climb.

I like the look of a 3-piece back, but it -is- a PITA to do; it's trickier to clamp, you have an extra join, and extra backstrip inlay(if you use them) and extra reinforcement. You also lose the automatically generated center line of a 2 piece back, so you're left to measure and mark everything. Not a great big deal, but truly doubles(at least..) the hands-on time necessary for preparing the back, bracing it, and fixing it to the rim. As such, most everyone charges more for a 3 piece back, even though there may be a small savings in material, though I've rarely seen any savings, but it does allow the use of nicer quality but narrow boards.

As for adding wings, well.... Shhhh!

Trevor Gore
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Re: 3 or 4 piece backs

Post by Trevor Gore »

Here's a four piece back.
Back finished.jpg
Back.jpg
All the panels are equal width. And no, I can't see the joins either. Makes no difference acoustically. I didn't reinforce the "quarter" seams inside on this (or others that I've done) and if you didn't know there were four pieces there is no way you could tell. Obviously, you need to line up the grain and run-out, etc....

Backs with wedge shape pieces in are both easier and harder...you don't have to make a grain match because it's not expected (that's the easier bit) but you have the issues with centrelines and gluing wedged shaped pieces, as Mario pointed out (the harder bit).

Mark Daigrepont
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Re: 3 or 4 piece backs

Post by Mark Daigrepont »

That looks great Trevor!

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