Official Luthiers Forum!

Hey…. So a buddy who is in the cnc game (like room sized stuff ha) asked me….”why can’t you carve the braces into the back of a top”?
So you would basically have a thicker quartersawn top… cnc the radius on the top much like an archtop, but on the back carve the braces from the same wood. Like there would be no glue joints …. Make any sense?

Now, my immediate thought is … nope that won’t work… but I’m not sure how to explain WHY it won’t work.

Please be gentle w me here haha


Sent from my iPhone using Tapatalk

The braces would be short grain and therefore weaker and more prone to breakage. It would also waste wood cause you would have to start with about a 1" plank.

Exactly. Having the ‘braces’ be the same grain lines as the top would likely be most problematic…

Still leaning:) thanks guys


Sent from my iPhone using Tapatalk

During the depression, cheap German "box fiddles" were common. They generally lacked corner blocks, and commonly had the bass bars carved into the tops. Some of them were actually not bad though...

But I wonder--there was someone out on the CNC thread that had done some interesting "built in bracing" on his tops. I wonder if laminating a thin strip of carbon fiber on the tops of those machined-in braces might give them the extra directional oomph that they need.

Dave

The "carved in" bass bar on a violin avoids all the problems I mentioned. It basically is parallel to the grain of the top so there is little run out. Also, the bass bar would not waste any wood because that wood would be hollowed out anyways. Another advantage is that it avoids the somewhat complex job of fitting the bar to the curved belly of the top.

However, you can always rough in the braces on the CNC




Sent from my iPhone using Tapatalk Pro

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

There was an article in American Lutherie in 2005 about the construction methods used at the time by Australian manufacturer Cole Clarke, an early CNC user. Although they didn't carve in the braces they did start with thick plates and carve in the linings, and also shallow pockets for the braces to aid in gluing. As far as I know they continue to build this way. Here is the summary page for the AL article on the GAL site: https://www.search.luth.org/the-cole-clark-guitar/ and here is the Cole Clarke web page : https://coleclarkguitars.com/

_________________
R.M. Mottola
LiutaioMottola.com

Author of the books Building the Steel String Acoustic Guitar, Practical Design of the Acoustic Guitar and Similar Instruments, and Mottola's Cyclopedic Dictionary of Lutherie Terms.

I don't check in here very often. If you need to contact me the best bet is via email through the contact page on my site.

Yes, they do and in practice it is a problematic design. Why? Because when a brace loosens you cannot get under it to clean out the failed adhesive prepatory to a reglue or even easily add fresh glue - the brace is buried in a perfectly fitted CNCd channel in the soundboard. I don’t think there’s a sonic benefit for the instrument in bracing via this method, it’s purely to make assembly easier.

Other “innovations” which Cole Clark is famous (notorious?) for would include utilising a Spanish heel for their production steel string guitars - they claim it avoids the need to ever have a neck reset (!!!) I guess those of us who repair guitars for a living could venture an opinion on this claim from CC, but opinions aside, this year is about their 23rd in operation so we will soon begin to see whether they are right or not.

With CNC they have managed to build in some wonderfully wasteful and problematic features! Using modern technology to cut labor and make an inferior product. So what else is new?