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with a 28 foot radius on the back?

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Total Posts: 58
can some one give me a detailer explination of what this means?
28 foot radius on the back.
Thanks dave

Feb 28, 07 | 12:04 pm

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Total Posts: 567
The back (and top for that matter) have a bow to them to help with strength and tone. The amout of bow is what the 28' radius is. Basically, if you took a 28' string, pinned one end to the floor, put a pencil on the other end, stretched it out and drew a circle like a compass, any section of that curve is a 28' radius. That curve is what you should see as a bow in the back of the guitar. There are a lot of different places you can get radius board and radius dishes. The Stewmac kits come with the braces already curved to the proper radius for the guitar and good instructions of how to glue the braces in to obtain the proper bow. LMI kits come with billets of wood that you need to cut and shape all of the braces to obtain the proper radius. The DVD does a good job of explaining how to do this. Many builders use radius dishes which have the curve in all directions, like a bowl, to help with the sanding of the edges of the guitar to create a 'perfect' radius in all directions. The dishes also help with the clamping of the braces and to top/bottom to the sides.

Hope that helps. Probably made it as clear a mud!

Feb 28, 07 | 1:39 pm
Ken Cierp

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Total Posts: 2262
Hi Dave,

I am not going to explain it here but I have tools and info on my web site that lead to the results you NEED to make a fine guitar.


By the way its usually 28 or 40 radius for the top and 15 for the back.

Enjoy the journey.


Mar 02, 07 | 8:01 am

Total Topics: 2
Total Posts: 26

I have just received my classical guitar kit from LMI. I have reviewed the plans and watched most of Robbie O'Brien's dvd. There is much to learn.

My first question concers the radius of the top and back. While I find comments regarding radius for SM and other kits, I can't find any specific recommendations for LMI Classicals. Your Mar. 02, 07 entry says 28 or 40 for top and 15' for back. Would that apply to the LMI Classical.

Jul 21, 08 | 5:20 am
Ken Cierp

Total Topics: 58
Total Posts: 2262
Ususally the backs on classics have only a very slight contour on the outside ends of the back braces. And this is there to prevent the possiblitiy of a concave appearance once the finish is applied. I have the LMII 1937 hauser print and see no indication regarding the actual contour. It appears that the rim has a slight taper increasing in size from the neck heel to the tail block again --- no dimension on the print. Note that some great classics are flat (no taper) and some are tapered opposite --- wider at the neck then the tail block. I have never seen Robbie's DVD I am sure it is good. However, for the classic builder (or any builder) I always recommend Sloane's book "Classic Guitar Construction" Its only about $20 and in my opinion it may be the best guitar construction book ever written.


Jul 21, 08 | 5:43 am

Total Topics: 2
Total Posts: 26
Ken, thanks for the response. I will order the book and also check with LMI. I have a Yamaha classical that fits the outline of the 1937 Hauser. It has a very slight radius on the top and more on the bottom. Maybe I can draw some conclusions from it.


Jul 21, 08 | 6:04 am

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