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I've been wondering what builders thought about this construction technique. Are there any advantages the "relief cut" has that the typical method of thinning around the perimeter doesn't have (other than saving time)? I haven't seen it up close but does this create a stress riser? It seems like it wouldn't allow as much movement or have as high of a stiffness to weight ratio as gradually thinning around the perimeter would. So what do you think of it?

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Jeremy Douglas

I think that if you're in a production environment like Taylor, and you want tight controls on your process, his relief cut would be a better choice than tapering the top thickness down over a large area.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

If I recall the bit they use is spherical (or at least bull nosed). This would only create a riser at the very edge of the cut and not at the bottom. It seem to be a somewhat practical way to keep and even thicknesses top and yet give it a bit more movement at the perimeter. Most of us do the sane thing by thinning the perimeter.

I would think hat tapering a top would be somewhat difficult in a production setting, particularly tapering it along the length. Since he's already set up with the CNC the shalow channel is an easy way to get something of the same result.

I, too, would think it a stress riser at some level. I guess we'll have to see how it works out in the long run.

You guys are using the term "stress riser" a little bit loosely.

I should rightly be used only for a sudden dicontinuity in the surface such as a scratch or an unraduised internal corner.

An external corner or a dish shaped channel is not a stress riser

Classic example of a stress riser is scoring a piece of glass to allow you to break it.

Other than saving time and money is there any tonal benefit over the tradtional method of thinning around the perimeter or is the 'relief cut' an inferior method used only to save time?

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Jeremy Douglas

Hello Gents,

I to would agree with Alan's assessment about creating any sharp transitions on a soundboard be it
internal or external radii. Under load they can become stress concentrators/risers that could lead to crack initiation and propagation.
I've blown up enough automotive parts in the last 20 years, my experience and judgement tells me radii on everything under load and deflection.

Just my opinion.

Cheers - Luc

Hey Luc, It's not so much that the external corner is a stress riser in itself but that it is easy to get a nick in it and then that becomes a stress riser.
Anyhow we are talking wood here which has a much greater toughness for it's strength than metal.

I have no idea how it sounds but I do think it is a great use of the technology which Taylor have available

Yeh, it does seem like a good idea for factory guitars. I just wondered, if any of the builders here had the ability would they choose the 'relief cut' over tapering the edges.

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Jeremy Douglas

I have played a few of these guitars, and they are pretty good, maybe a 'bit loose' on one of them. The sales guy told me about the little trench. Compared to a Larrivee, the Taylor rocked! The Larrivee was dead, played it for 20 seconds. (He had very limited selection) He also said alot of people 'can't tell the difference'.

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