Maximum radius

[deadedith]

Just wondering - if the minimum radius for a top is - flat; what is the maximum advisable radius for a 'flattop" guitar top? And as you approach that maximum, what are you gaining/losing?
DaveB

[Tony_in_NYC]

The more of a radius you put on the top, the more flatness you lose. Is that clear enough? Sheesh.

[deadedith]

I had not thought of that.

[tippie53]

What happens is you throw the neck to a higher angle. I don't go above 28. If you blow this geometry you will never get a good neck set on the steel string. It isn't so much about the radius as it is to match the numbers for that magical 1/2 inch string height , and match the neck relief.
When I use a 28 dish I still flatten the area at the neck fretboard extension . Martin puts a 1 1/2 degree on the tops and braces the top with a 42 foot radius on the braces .

[Tony_in_NYC]

I had not thought of that.

Just as I had suspected!!

To add to what I initially said, the greater you make the radius, the smaller the dome becomes. And vice versa.

[deadedith]

Thanks John.
Tony, I'm sure you're right, because......well, just because, but really, if I increase the radius, the dome lessens? Hmmm
DaveB

[Darryl Young]

Yes, as the radius gets longer (larger), the top gets closer to being flat and as the raius gets smaller, the top gets more arched.

A small radius (very arched top) can be very stiff and tight sounding. A large radius (close to flat) will work fine......even flat will work but you have more risk of the top splitting when the humidity gets low.

[Tony_in_NYC]

I didn't even have to defend myself. Good times.

[deadedith]

I've thought about trying a concave top with a very shallow radius, with a matching concavity in the back. I think it might give a unique sound. But the strings will stay on the outside.
DaveB

[deadedith]

Rick - After your thoughtful reply, I am ashamed to say that yes, I was putting you'all on.
It is what I call my 'sense of humor' and what the rest of the sane world calls being a PITA.
Sorry.
DaveB