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  #16  
Old 05-05-2017, 03:50 PM
Ned Milburn Ned Milburn is offline
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FWIW, a guitar is not a circle. So a circular radius seems out of place to me. I create my solera for top building with an egg shaped dome in it. From the Spanish style of building, I get the concept of fitting the fingerboard flush with the top and having the top conform to fit perfectly - sans fillet (wedge) - for neck angle / fingerboard extension / saddle height.

Why use a circular dome?? Because it is easier...??

Why use a wedge?? Because you need a wedge filler because a circular dome was used.

So is the circular dome shape easier or not...?? Is it better or not?? If it requires a wedge is it making it easier or more problematic...??

Or, you can just make a custom shaped top dome that fits, and that doesn't require a wedge.

Your choice.
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  #17  
Old 05-05-2017, 04:54 PM
TEK TEK is offline
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Ned,
This is more about why I started this thread. The idea of using a dish to sand the rims with a radius means there will be a dome where the neck mounts. There was always talk about sanding a radius on the rims but very little talk about what to do with the neck area after. I just followed along blindly so to speak even though it did not make much sense to me.
Most of the time I just sanded the top to make everything line up and it worked fine. I was just curious what others did to correct because I felt the correction should be done before gluing the top on.
You can bet I will be slowing down and making the next one with the right angle before the top goes on.
Travis
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  #18  
Old 05-06-2017, 03:31 PM
Alan Carruth Alan Carruth is offline
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The Spanish method of making guitars uses a solera. The top is braced on the solera, the neck is glued to it, and the rest of the guitar is built around that. The neck angle is taken care of in the fixture. Traditionally the top is only bellied in the lower bout with the edge left flat. The waist bar and the upper transverse brace are both flat. Each maker uses the doming that he feels is right, and there are a number of different systems. This means that each top brace has a different curvature. This is not a problem because the fans on a Classical top are low enough that you can press them into shape as they're glued, and they'll retain most of the dome, with only a bit of springback.

Steel string guitars tend to be X braced, and the braces are taller: they can't be sprung into shape. You could fit them, the way an archtop or violin maker fits their bracing to the individual curve of the top, but that's time consuming. The radius dish is a compromise that makes it fairly easy to fit the braces to the top and produce a dome that works reasonably well. It's not too hard to produce the correct brace profile, and even approximate methods seem to work OK.

Of course you can argue about what the best shape for the top dome is, and people do - endlessly. In the end this seems to be what's been called a 'wicked problem': one that is not well enough defined to converge on a single solution that is provably the 'best'. If it works for you it's probably good enough, and likely not far from whatever the 'best' is.

Finally, I'll mention the most important rule of all. My violin making teacher used to say that there are a lot of ways of doing it, but whatever you do it has to look like you meant it.
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  #19  
Old 05-06-2017, 05:47 PM
TEK TEK is offline
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Quote:
Originally Posted by Alan Carruth View Post

Finally, I'll mention the most important rule of all. My violin making teacher used to say that there are a lot of ways of doing it, but whatever you do it has to look like you meant it.
That reminds me of the time I was teaching a kid how to shoot a bow and arrow, I had a target with 5 circles on the butt. He shot his first arrow and was dead center on one of the circles. I said great shot, is that the one you were aiming at?
He said quickly YES , which one did I hit?
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  #20  
Old 06-18-2017, 05:40 PM
Albert D Albert D is offline
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I ran into the same issue as the OP. I'm working on getting the neck angle right in relation to the bridge by flossing with 80 grit at the heel but due to the radius on the top have that same gap under the fingerboard extension. I guess I'll be making a wedge.

My thought was to use the same material as my neck binding which is koa. Should I get the neck angle set first and go from there. Is it a matter of shaving it close and doing trial and error fitting on the guitar?

I'm sorry for the basic questions but I got to this point with the help of an experienced luthier who has since moved away then had a stroke. I want to get it done right as much for him as myself.
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  #21  
Old 06-18-2017, 09:29 PM
TEK TEK is offline
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Albert,
Yes I would get your neck angle set first. Once you have that set you can make a shim to fill the gap. On mine I used the same mahogany I used for the neck. Get a good clean join up tight against the part of neck under the fingerboard and glue it to the fingerboard. Keep fitting and trimming it until it is just right on both sides. You can floss it like the neck if you want. Match the finish to the neck and it will not even be noticed by most.
TEK
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  #22  
Old 06-18-2017, 09:54 PM
Albert D Albert D is offline
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Quote:
Originally Posted by TEK View Post
Albert,
Yes I would get your neck angle set first. Once you have that set you can make a shim to fill the gap. On mine I used the same mahogany I used for the neck. Get a good clean join up tight against the part of neck under the fingerboard and glue it to the fingerboard. Keep fitting and trimming it until it is just right on both sides. You can floss it like the neck if you want. Match the finish to the neck and it will not even be noticed by most.
TEK
TEK, Thanks for the ideas. I had not thought about flossing it. Great idea. It will be a slow process for me but that's fine. I just want it right. I will just look at it as another fun challenge.
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  #23  
Old 06-19-2017, 09:45 AM
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Pat Foster Pat Foster is offline
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This might work for you: Use a flat UTB and any other braces north of the soundhole, and after driving the bus, sand the rim flat north of the waist, using a spacer to elevate the rim at the tail. The thickness of the spacer will depend on the radius of the dome and the length of the body. Takes some experimentation to nail it, but it does the job.

Pat
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