Radius Dish

[Zen]

Hi from Ireland. I'm a newbie here so just to say a big Hello to all you builders of guitars around the globe.
I am starting to build a dreadnought from the stew mac kit available online and so far so good, but I have come up against my first problem due to the fact that I dont have a radius dish. In the catalogue they recommend making a paddle type sander with a 1-5 degree angle on one end and a 1- 1/1/2 degree on the flip side. Its been 40 years since I did anything with angles --59 next birthday- so anyone help me out on the easiest way to get around this problem. I did leave it a bit late in life to start building but I've been infatuated with guitars all my life and played professionally for most of it as well. Its great to see a forum like this and i'm looking forward to being a part of it
Best Regards to all

Rusty

[tippie53]

this isn't all that hard , I don't agree with a 5 degree all around the back , as this angle changes from just about square to 5 degrees. The top , you can do that at 1 to 1 1/2 degree. To get the back angles close you can set the sides top down and in the middle of the body place about a 4 7/8 inch high post. then sand the edges letting that post set the angle to the side as you go around.
That should get you close enough for what you want to do
Also check out you tube , this link can help you with your build.
http://www.youtube.com/results?search_q ... lAYi0eWl9Y

[Zen]

Thanks a million for the tip on sanding the kerfing. Not sure I still get it but I will try what you suggested later today. As a matter of interest would you know the measurements needed to make that sanding stick mentioned in the martin manual, as I may end up trying it anyway. It says one wedge should be 5 degrees and the other 1.1/2 degrees. I 'm hopeless at degrees and would prefer if thy simply said make a wedge 8 inches by 3inch or whatever it should be and glue it to a board etc.
Once again Thanks so much for advise so far on my first build and if I can get over this sanding hurdle then I might be getting somewhere.

this isn't all that hard , I don't agree with a 5 degree all around the back , as this angle changes from just about square to 5 degrees. The top , you can do that at 1 to 1 1/2 degree. To get the back angles close you can set the sides top down and in the middle of the body place about a 4 7/8 inch high post. then sand the edges letting that post set the angle to the side as you go around.
That should get you close enough for what you want to do
Also check out you tube , this link can help you with your build.
http://www.youtube.com/results?search_q ... lAYi0eWl9Y

[tippie53]

the angle changes as it travels around the guitar, For the most part it is square on the tail and goes to 5 degree on the neck block , this is for the back
The top is basically square with a 1 1/2 degree at the top from the sound hole to the neck block. This area is a flat ramp to allow a flat plane for the freboard

[Kevin Waldron]

Zen,

John and I both sell radius disk...... we both realize that everyone can't afford them, shipping is too expensive, not sure they will continue to make instruments, and lots of other reasons or they want to make there own. The following link is on another forum and it has a great way of making your own radius dishes.

http://www.ukuleleunderground.com/forum ... dius+board

Hope this helps.

God Bless.

Kevin Waldron

[Darryl Young]

You can make a radius stick and do the same thing as a radius dish.

http://web.mac.com/magads/Site/LMI_OM_K ... Edges.html

To make the stick, either buy a radius template to draw the correct curved line on a stick.......or draw one in a CAD program and print it out and use it. Of course, you can have a buddy do it if needed. I think print files of common radii have been posted on some forums that you coud print out (or take to printing facilty and have printed). There are freeware CAD progrmas that will draw an arc that you can download.

You could also tie a 15 ft (or 28ft or whatever radius you need) to your router and use that to swing an arc as you route. Or tie the string to a pencil and use that to draw your arc on a stick.......then trim close on your bandsaw and sand to the line and use the radius stick like in the link above.

[watergunn]

I have used a home made 15 foot radius stick for the back of the four that I have built. I used a 28 foot on the top of the first one.

After doing the first build I did invest in a 28 foot dish. It really is easier, for me at least.

I will be getting the 15 foot dish soon.

Good luck and have fun.


RG

[Zen]

Thanks Guys for all the great advise. I managed to make my Sanding Stick and used it to sand the kerfing so now the top sits nice and snug after notching for the braces.

However i do now notice that both the blocks are a little lower on the back--about a 1'16th inch lower than the sides, so that means when i glue on the back it will not sit down tight on the blocks ?

The top was just right so how is it that the back is different ?
Should the back be sitting on the end and neck blocks tightly? Should I slot in a piece to bring the blocks up to the same lever as the sides. Theres not much in it but it worries me that its happening so any advice appreciated as usual
Regards

Zen

[Ken Hundley]

I tmay be that the inside edge of your tail block was not proud, so to sand enough off to get good contact using what ever radius method you choose, you sanded 1/16" off to get there. Not a big deal, an you, if anyone at all, may be the only one that notices.

[watergunn]

You can always glue a piece of scrap wood on the to of the brace to be even with the top of the rim.