Radius disc????

[Legolas]

Mark, that is correct. A 15' radius dish for the back and a 28' radius for the top.

-tommy

Thank you Tommy!

[Tarhead]

You can build up a radius dish with thin pieces wood strategically placed around a circle rather than cutting out a dish. Dave Higham posted an excellent tutorial here:

http://www.ukuleleunderground.com/forum ... adius-Dish





To calculate the thickness of the support pieces (AKA: rise of the curve) use this worksheet:
http://webcache.googleusercontent.com/s ... clnk&gl=us

[Ben-Had]

There are different ways to do this. I radius my X braces 25' but sand the rim dead flat, then sand in the angle from the neck block to just below the sound hole to the complimentary angle of the neck. I sand my back braces and rim to 12' radius. So my dish is flat on one side and has a 12' radius on the other. For my braces I have a 2' long 4x4 with a 25' radius on one side.

[ruby@magpage.com]

Correct me if I am wrong, but before computer generating the shape of the sides, a radius dish may have been extremely important to take down the sides to fit the top and back. But since the shape of the side is well established (and provided you assemble the the neck and tail blocks accurately) then there is not much material to remove anywhere.

I have only built a couple guitars but have had great success with a 2X4 dished along one 3-1/2" face with a hole in the center that rides on a bolt sticking up to keep it centered. Chalk along the edges of the rim tells you when you have bevelled everything, and the bolt makes it easy to keep things even side to side and end to end. You only do this operation for a minute before installing the lining and minute after installing the lining (and you can use a block plane to take most of the lining off before sanding) so I don't see the advantage of investing in dishes unless you are building lots of guitars.

I made one with a 15 ft, a 28 ft and no radius and cut handles at either end - works a treat.

And cutting that shape always is described as way more complicated than it is. Someone should publish a list of the dimensions off of flat across a 24" distance for each radius , then use this system to mark the line:

(It is taking 2 posts to get the photos in)

DSCN1721.JPG

DSCN1722.JPG

DSCN1723.JPG

[ruby@magpage.com]

continuing - seems like the forum will only allow 3 pictures
by the way - this is a boatbuilding trick

And it will take one more post to get the photos to you

DSCN1725.JPG

DSCN1726.JPG

DSCN1727.JPG

[ruby@magpage.com]

Last one - You will make these marks and then cut along the small edge of, say, a piece of 2X4 with straight grain and no knots to keep it stable. My batten is 24" between handles - the handles are 3" long and I put the piece in the lathe and turned the handles, but you could cut them

The worst part is using the formulas for each radius you will use, but once you have the distance off the line between 2 points, this method is dead easy.

these photos shows the application of the batten

IMG_0866.jpeg

IMG_0864.jpeg

DSCN1740.JPG

[darren]

@ruby - I've read this method described several times but haven't grasped it - surely my own fault. Thanks for the detailed photos and explanation it's much clearer now...