Official Luthiers Forum!

Just out of curiosity, what is the most extreme radius you have built into a soundboard? What challenges do you face the more spherical you get?

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Time is a great teacher, but unfortunately it kills all its pupils - Louis Hector Berlioz

Chansen / C hansen / C. Hansen / Christian Hansen - not a handle.

Christian

I radius my top braces to 13' with the utb at 10' but I don't build "spherical". The main challenges will be fitting with your overall build to give the sound you want (you might find it tricky to create the Holy Grail pre-war American sound for example), making sure the bottom of the bridge profiles to fit the top, and if you are using "traditional" neck/body techniques getting the fingerboard extension to fit to the top with a straight neck geometry.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

At McPherson we use a 15' top radius. On my guitars I use a 25' or 30'...I have been leaning to the 30' more often than not.

The fitting of a bridge on a very domed top would be the greatest challenge I think. Of course we use a cantilevered neck so some issues with fingerboard extension fitting are sidestepped.

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John Mayes
http://www.mayesluthier.com

From what I have read most tops are radiused for structural reasons... What does the radius do for sound/tone? 13' seems really extreme... does that change the way your guitars sound in you opinion?

John - Are you leaning toward 30' more because of the end result (sound you want) or ease in building?

_________________
Time is a great teacher, but unfortunately it kills all its pupils - Louis Hector Berlioz

Chansen / C hansen / C. Hansen / Christian Hansen - not a handle.

Christian

I do it for sound/tone reasons although there are structural benefits too. Where possible I post sound clips of my guitars and although not as good as playing one live mught give you a flavour. Check out the sounds page on my website - I have limited space to host .mp3 files and have to "move" things around from time to time so apologies if not all the links are currently working.

I view the guitar top as a drum-head and the top doming gives you a system under tension like a drum head. "Activate" such a system with the strings and the disturbed tension adds to the tops responsiveness. Amongst other things, players always comment on how loud my instruments are and they have very good projection. The doming also helps imho with mids and trebles and then you can work on getting the bass you want. It's all part of my "system" and when you look at a 13' domed top it's not really that extreme in my view. In fact I suspect a lot of great old guitars end up there eventually. There is a great thread on the UMGF about this amongst other things that you may have already seen.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010