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So I am starting in on #1. I am following Guitar making by C&N and my own woodworkers intuition as a start. I am currently working on the neck and bindings. Actually I'm doing the neck blanks and bindings for my first 3 at one shot. From that point I will work #1 all by itself. I am planning out ahead and ran across a puzzle. C&N recommend an arch template for the top of 1/8" in 18" which works out to an acceptable 27' radius. So far so good. So then we get to laying out and cutting the braces and they are describing offsetting the template on the lower face brace blanks by 1/16" at one end. They describe similar offsets for the back braces as well (Though the template is different). So what is the purpose of offsetting the template? It has no effect on the radius as that is already determined by the template. It makes no difference in orientation to the grain as it is perpendicular to the radius face ( Run out excluded of course). The slight difference in thickness at one end doesn't really matter either as the brace ends as well as the entire brace will be carved down once glued to the plate. So what is the reason for this? what am I not seeing? Thanks.
Brian

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Hmm, I just took a look at the book, and I think it's a confusion of terminology. I think he's making several templates, with different radii, defined by their span and offset (with his metal bar and push pins setup, span is the distance between the outer pins, and offset is how far from the straight line the center pin goes).

I dome my tops the same way, but I don't bother making brace templates. Just draw a straight line along the brace blank at the offset I want, and plane an arch into it, until I reach the marked line at the ends, without removing any material from the center. Don't worry too much about it, it doesn't have to be a perfectly spherical curve (actually, the push pin and metal bar setup creates a spline curve). The important thing is the relationship of the upper transverse brace offset and X offset.

I also leave the central 2.5" of the upper transverse brace flat, so the fingerboard extension isn't sitting on a side-to-side hump. So the curve is a little tighter on the outer edges there than it is on the other braces, to get to the full 1/16" offset. Particularly necessary if you use a headblock extension (I do), because you can't butt a flat headblock to a curved brace

Having taken Cumpianos course I can tell you that even though the offsets make no difference in the radius of the top, they do make a difference in the thickness of the braces at the ends, which affects the overall weight of the finished and carved brace.
The purpose of carving and shaping the braces is to get rid of the wood that's "Just along for the ride" and the end thicknesses factor into that.
If you really want to know more you can e-mail William off his website, I'm sure he'd be happy to fill you in.

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Old growth, shmold growth!

Thanks, I wrote to bill and got a prompt reply, thought I would post here fore anyone else who may ponder this same dilemma.

"The LFB is very short, and the radius is almost insignificant. You can choose either the 1/16th offset (note that it's 1/16th measured off one end, so the actual resulting offset, or curve is 1/32) or use the 1/8 in 18" template.


Maintaining a precise numerical degree of soundboard curvature is not obligatory. What we are trying to achieve is not a certain arch or dome of the soundboard, but simply to impart a very faint arch/dome in it--in effect, making it simply--not flat. To impart a significant arch into the soundboard would make it excessively stiff, not to speak of increasing the complexity of the body/neck angle geometry. To leave it flat would leave the plate more prone to collapse under the string tension than otherwise, and we would then have to increase the size of the braces to make up for it.

Best wishes,
William Cumpiano"

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I was thinking of something else, LOL! I was commenting on the fact that the x-braces are thinned more on one end than the other. If you are reading Bill's book, might as well just e-mail Bill is what I say.
I was recovering from a cold and was heavily medicated upon my first reading.

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Old growth, shmold growth!