www.KitGuitarsForum.com

Beginner question... I am building a tenor ukulele for my first instrument and I happened across a go-bar system with a 20 ft radius dish and a 28 ft radius dish. I have used the 20 ft for the top. Borrowed a friend's shop and 12 ft radius dish for the back. I plan on building acoustic guitars and perhaps a few ukuleles. I wonder if anybody can specify the several most common radiuses people are putting on their instruments. At $100 a pop, I don't think I want to purchase eight or ten of these. thank you for your help! :-)

I use 28' and 15', common Martin radii for top and back.

they would likely work Bob Gleason should pop in he makes ukes for a living

Chuck asked that question on the UU forum. Here is my copy and paste reply from there


I would have used the 28' for the top. The tighter the top radius is, the more difficulty in fitting the neck joint, neck extension, and the bridge. I use 30' for most of the top and 15' for the back on guitars and ukes. The 12' you used is a common back radius too. Truth is that I doubt many of us actually end up with the radius we try to. Certainly for most shop made radius dishes, the true radius actually varies a bit from the one we tried to get. Even CNC made dishes often don't stay in the radius they were machined to. Whether the back is 25, 28, or whatever does not matter that much. If the top varies a foot or 2 from what you try to get does not matter either. Most builders use a flatter radius though, 25' or more, all the way to flat.

And, after my reply another builder brought up the appropriate comment that there is always some spring back on the braces too, so further confuses the actual radius issue.

I've been using 25' for tops and 15' for backs.