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I am working on getting started on my 1st Guitar. I have been building tools and jigs for the guitar and am using Kinkead's Book and Plans. In his book he makes a dish for the top and back of the guitar but he doesn't tell what radius it is. The best I can figure out is the top is 50' and the Back is 25'. am I close or is there even a dish radius on his guitars. Thanks in advance for any help or advise on the top and back radius.

James: Not sure what Kinkead does for the radius of the top and back. A fairly common set of radii are 25' for the top and 15' for the back. There are others plus or minus.For your first guitar you don't have to get too excited about the actual numbers. A few feet in either direction does not make much differance. Good luck with your first one.
Tom

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A person who has never made a mistake has never made anything!!!

the top can range a good bit. I use a 1 1/2 degree angle as does Martin . most commercially available necks use this so you want to give that a consideration unless you carve your own necks .
http://www.youtube.com/watch?v=QYHPCeVRUA4
give this a look see to see how I manage the geometry on the side to set up the top

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Thank you for your information. I am still having trouble with figuring out how the braces should be radiused, it seems like each one has a different radius. Is this just because of the location on the dish or am I just trying to think it out too much.

I think different people do it different ways, but a lot of people, including myself, will radius the brace by sanding it at it's approximate location in the dish. It should be a spherical dish, with a constant radius wherever you are, but you don't always want the braces leaning towards the center of the sphere.

Mike

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Mike Lindstrom

Mike - I gave some thought to this before radiusing some braces recently and decided it seemed more appropriate from a structural standpoint to just always sand the braces in the center (bottom) of the dish, but now you have me questioning my decision. Why do you feel you would not want the braces "leaning" toward the center of the sphere? It seems to me you would, but I don't know. To be clear, I'm not saying you're wrong...just trying to better understand the issue.

I am still wondering If anyone knows what radius Kinkead uses in his book. He doesn't say but he does give some Measurements.

Thank you.

OK . so what are the measurements ?? reverse engineering the radius is easy .... not to say that he uses a constant radius, but if you know the drop/curvature over a given distance, its pretty easy to do, using the formula for a circle ....

As for braces leaning if you sand then on the middle of the disc, then glue them towards the outer edge of a top or back, I did the math once for the back braces .. the braces furthest away from the centre would only lean about 1.5 degrees ... no biggy IMO, and I have never thought about it again ... besides, I carve the peaks to look like they are centred, so you can tell how I did it anyway ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Good point, Tony...I wouldn't think it would make much difference either way for our purposes (guitar top and back bracing). In theory, though, the more the brace "leans" relative to the surface to which it is glues, the less strength it would impart. At least in theory...