Official Luthiers Forum!

Probably a very very broad question, but what is the best radius for a top and back? In other words, how does the radius affect the structural and tonal qualities of an instrument? Also, what are the effects of not having a radius at all? I'm also looking for a very inexpensive yet effective way to achieve doming if I absolutely must.

Ian

Ian-
Lots of guitars have been built 'flat'. However, putting an arch in the soundboard/back makes the plate more rigid/'stronger' with no increase in weight, and does tend to prevent the plate 'going concave' with humidity changes.
Also, flat plates tend to look 'hollow' (optical illusion), so a slight arch makes the guitar better-looking to most folks.
You do have to decide whether you want to make the arch a section of a cylinder or a sphere.
For cylindrical arching, a curved or flexible caul and curved braces will do the trick.
For spherical arching, most folks are using 'radius dishes' in the steel-string world. For spherical arching the top of a classical, the traditional method is a flat workboard (solera) with a shallow hollowed out area centered in the bridge area.
Following one of the standard books for guitar building will give you a specific method.
You do want to make sure that your arching scheme works with your neck geometry. If it doesn't, you will have problems making the guitar action/playability 'correct'.

Cheers
John

There are many advantages to doming. http://www.youtube.com/results?search_q ... ues+creek+
this link may help to show you. One big help is that you can get a straight line on your neck and avoid the 14th fret hump.
Good luck

_________________
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

It would help quite a bit if I had a direct link to the video. I'm having trouble finding it.

http://www.youtube.com/watch?v=QYHPCeVRUA4
this will show you how to use the disks to adjust the geometry for your neck angle.

_________________
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