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Tone Ring cross section
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10104&t=10716		 Page 1 of 1
Author:  Ron Belanger [ Sat Feb 03, 2007 4:36 am ]
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Hi,
I am currently building my 1st reso. Round neck with a cutaway. I am using Gary Dusina's approach to a tone ring with sound posts and baffle.
My question is about the cross section of the tone ring. Gary uses 1 3/4" wide by 1/2" deep gluing 3/8" and 1/8" baltic birch rings together and then to the top which gives him a 1/4" x 1/4" rabbet assuming a top thickness of 1/8". I am thinking of reducing the width to 1" and increasing the depth to 3/4". This increases the stiffness of the ring by 93% and reduces its weight by 14%. I am also thinking of gluing the tone ring blank (12 1/4" diameter) to the top and cutting them both together and use rabbet bit to cut the ledge for the cone and spider.
Any thoughts or comments?
Author:  LouisianaGrey [ Sat Feb 03, 2007 9:45 pm ]
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He's using two pieces for the tone ring because he's using a fairly thin top and he needs the drop so the spider won't touch the coverplate. The ring doesn't need to be that thick for any other reason, because it's glued firmly to the top and the support posts hold it all together.

For the 1/4 " tops I use I just cut a single circle from 1/4" ply for the tone ring and glue it to the top after I've cut the circle out. If the top is stiff anyway then the stiffness of the ring is a lesser consideration. I'm steady enough with a jigsaw to be able to cut the circles in the top and the ring pretty well - it doesn't usually need much cleaning up with the belt sander. Besides, I've done enough damage with routers that I use them as little as possible, so although the rabbeting bit ought to work I've never tried it.

Don't be tempted to make the shelf the cone sits on wider than 1/4", by the way, that will just ruin the tone (guess how I know).

The only really thick tone rings I've seen are in the Fender, which greatly puts me off the idea because as a dobro it's a piece of garbage.
Author:  Ron Belanger [ Sun Feb 04, 2007 4:39 am ]
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Thanks Peter,
My top is a little on the thin side as well, so I will probably go with a slightly thicker tone ring. And thanks for the heads up on the rabbet. Gary says he allows about 1/16" extra on the diameter of the cone. What are your thoughts? Should if fit snugly or should there be a little wiggle room.
Author:  LouisianaGrey [ Sun Feb 04, 2007 5:29 am ]
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There needs to be a little room because under string tension the cone will spread slightly. 1/16th diameter is only 1/32nd all the way round so it's not like it will be really loose anyway, and as long as the neck and tailpiece are aligned correctly the string tension will also hold the cone in the right place.

If you do make the hole a fraction too small you can always trim the rim of the cone - I sometimes have to do that when fitting Quarterman cones to far eastern import dobros, because the original cones are slightly smaller. Again, 1/32nd all round isn't much and it doesn't do any harm.

When I think about it, the other alternative some people do to fix the Quarterman/import problem is to rout the hole slightly larger, and I assume they use a rabbeting bit for that so it should definitely work.
Author:  Ron Belanger [ Mon Feb 05, 2007 2:19 am ]
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Thanks a lot. I appreciate the help.
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