Official Luthiers Forum!

Well, I had my first experience with shaving braces this past weekend... with noticeable improvement to the guitar in question!

I had picked up a used, Asian made guitar the other day on eBay for a couple of hundred $$. It's actually a very nice looking guitar, small jumbo size with Engleman spruce top, rosewood back and sides (all solid woods), and a very deep body (like the Gibson Nick Lucas). It's called an Orpheum, made in Indonesia, which Tacoma marketed for a short while. (The reviews on Harmony-Central were very positive!)

Anyway, after addressing several set-up items, it seemed that the guitar was still very stifled / muted / wimpy sounding for its size. I had been reading some recent posts on the Martin forum about shaving and scallopoing braces, and I have been working with a couple of luthiers over the past year (building an LMI kit guitar), so I wasn't afraid of getting in there and going to work. Plus, the guitar didn't cost me that much, so I thought 'what the heck'.

This guitar had not just one but two tall, thick perpendicular braces behind the bridge plate. Plus it had a couple of (again, very tall, thick) braces on each side of the X-brace, parallel and a little behind the soundhole, where the only thing I could find in my other guitars were thin, flat strips/bars. I noticed that someone had already done some thinning on the X-braces from the X on back toward the rear bout. So, again, what the heck...

First I scalloped the two perpendicular braces behind the bridge plate down about 1/2 way in the middle, tapering back up toward the ends, and then did the same for the side, parallel braces; I also took the X-braces down a bit more as well. When I strung it back up, the difference was very apparent! It was much louder and 'alive'. Needless to say, I was a happy camper!

On a side note, I was just reading another thread on guitar weight recently... I bet this guitar weighs 30% more than most, if not more! (I'll have to find a way to measure it soon).

I know that the back braces don't make nearly as much difference as the top braces do, but is there room for improvement, especially if the guitar is (severely!?) over-braced and over weight / overbuilt to start with? Also, is there potential benefit from shaving / scalloping the braces in FRONT of the X-brace as well?

Any help or thoughts would be greatly appreciated!

Ken, welcome to the forum. I can't help with your question but I can bump it back up to the top.

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Bassethound, you are a gambler.

You won the hand.

I did the same thing with an Ibanez I purchased last year for my son's first acoustic. Solid wood top, too little sound, heavy bracing, non-scalloped.

I succeeded in completely voiding the warranty, and making the guitar sound at least 30 percent better. Very similar in results as your guitar. Welcome to the OLF.

Shave on.

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http://www.dickeyguitars.com

Welcome, Ken,

Bracing in front of the intersection of the two legs of the x-brace is generally
not scalloped.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

You won the hand, but the outcome of the game remains to be seen.

Most production guitars are over braced, simply because they have to ensure that they will stay together for the duration of the warrenty. They have no way of knowing whether they might have put the weakest set of braces on the weakest top in the place, so they design for that worst case, with a safety factor. The good news is that, most of the time, you didn't get that bad wood, and you _can_ safely reduce the bracing. But, unless you know some way of measuring the strength of the top, it's really easy to go too far.

This is particularly true if you 'scallop' the braces, making them lower in the area of the bridge, since that's the part of the top that has the highest stress. Tapered bracing, with the high point near the bridge, is much safer.

When I'm teaching 'plate tuning', a sort of 'high tech' tap tone method, I tell students that the area of the top at the bottom block is 'all' about tone, and the area of the top at the neck block is 'all' strength. Reducing the shoulder brace usually won't effect the tone to speak of, and reducing the size of the lower tone bar won't generally hurt the strength if it's done within reason. The real transition point is the line of the bridge: generally speaking reducing braces forward of the bridge, or, say, the X crossing, won't help the tone much.

OTOH, reducing the braces forward of the X crossing can certainly hurt the strength. To me, the critical area is between the bridge and the soundhole. It's no accident, IMO, that the two most successful bracing patterns of all time, the 'fan' and the 'X', both concentrate bracing there, while spreading it out behind the bridge.

Dave Hurd's deflection measurements are, in principle, a great way to know how far you can go with brace shaving. Even just looking at how much that spot 2" in front of the bridge dishes in when you put the strings on can give you a lot of reassurance (or something to worry about). The big issue, of course, is that you need to develop a data base to know what the measurment means. If you had that measurement on a lot of good sounding guitars that had stood up for a long time, you'd know just how far you could go in your shaving before you got into trouble. Lacking that, it's a crap shoot.

Thanks, guys, and Alan, a big thanks for the detailed response. You gave me pretty much the answer I was expecting. I didn't think that there was much to be gained by shaving forward of the X junction. And to be more precise, I did actually taper the X brace behind the junction, rather than scallop. I did scallop the lower and side tone bars, though.

Overall, I must say that the sound improvement on this guitar turned out to be REALLY impressive. I played it for a couple of hours last night, and couldn't put it down!

I'm still wondering, though, if there's anything to be gained by reducing the back braces a bit. They seem (like the top) to be WAY overbraced. I know that there's probably not much to be gained by reducing the back, but I enjoy the work, and like the idea of getting every bit of improvement I can, within reason of course.

On another note, I'm looking into the Ibex finger planes. Is there a particular size that I should get for planing inside a finished guitar?

Thanks for all the sound advice and encouragement!
Ken
Durham, NC

Hi Ken! Great to see you again. Here's hoping you and your loved ones made it through the holidays, and school isn't beating you up too much these days.

Glad to hear your scalloping excursion went well. Hope we can get together sometime to grab a bite and catch up. Take care.

Bill

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Eagles may soar, but weasels don't get sucked into jet engines.

someone has small hands. I'd have to take the top off to tap tune such a beast, I think. My right mitt will not fit into the sound hole of most guitars.

Rodger H. Siminoff's book The Luthier's hand book has an excellent chapter on "tuning" the braces. I am going to try that right after I build my first two or three guitars to make sure I get the building part right!

I got the book from one of the sponsors, Stewart-MacDonald.