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Could be a design enhancement. I've not built any of the 175/335 style guitars, but have on an occasion used parallel tone bars beneath the bridge pad on acoustics. I think the notion might be that (in the case of acoustics) tone bars benefit with direct contact of the x-braces. It may offer some resistance to torsion as well as enhance the vibration of the overall brace system.
In the case of the 175 pictured, though, I wonder if it may also be so there is a suitable substrate for the pickup & ring mounting screws? Another intent may be to lend to the instrument's sustain or general tone character. If memory serves, the 335 types use a solid spruce or mahogany billet of wood down the center, between the plates. Gibson advertises this reduces feedback/enhances sustain (I think- but please don't quote me). Just seems to be what I recall from some advertising.
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12-01-2014 11:06 PM
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kerfed bracing is vintage correct.
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For a collector, I guess vintage anything is all that matters. From a construction standpoint, it was probably decided on by some accountant, and adds nothing positive for an instrument. Not to knock anyone's guitar, just point out that manufacturers do sometimes resort to lunacy to save a couple bucks. I own a pre CBS Fender Jaguar from 1965. It's vintage correct, but the tailpiece design is a piece of garbage. At this point Norlin era Gibsons might be considered by some to be vintage, but for my money they're novel at best. Just sayin'...
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early '50's ES 175
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Definitely inferior.
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what's most surprising about this image is that it shows the brace glued with the flat grain mated to the top plate. The grain lines appear to be fairly quartered but they were placed sideways. Quarter sawn brace wood would be positioned vertically, with the grain edge glued to the surface, by a even a novice Luthier. This is why factory guitars sometimes come up short, even if they are vintage models.
Last edited by JGL; 12-02-2014 at 06:02 PM.
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Agreed! It's also why some 175s with kerfed bracing suffer from top sag and/or splits in the bracing while others do not. It's these little inconsistencies . . and to your point, they NEVER happen with the smaller boutique luthiers. In order to be recognized as a luthier, instead of just a guitar builder . . . one needs to understand wood.
Originally Posted by JGL
Last edited by Patrick2; 12-02-2014 at 11:50 AM.
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I can pretty much guarantee that neither Pat Metheny nor Jonathan Kreisberg knows if his 175 has kerfed braces.
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No, but I bet their guitar techs do - lol. I'm not saying it's a bad guitar, but based on the thread's submitted concern and photos, there are apparently some ridiculous iterations out there. Guys at Metheny's level would toss one out if the top started sagging anyway. There's nothing wrong with expecting the craftsmanship on the inside of your instrument to match it's outside, especially at Gibson's inflated prices. IMHO.
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Maybe they know . . maybe not. But, I can pretty much guarantee that if the top on one of their 175s started to cave in, they'd learn in a damn hurry. Wouldn't they? I don't think that anyone here said that all 175s with kerfed bracing are destined to sag. But, some do. The reason for that, almost always is kerfed bracing. It ain't an easy fix either. The tech has to disassemble the guitar, go in through one or both of the pup holes and jack the top back up into position and rebrace it. Some techs try to just repair and shore up the existing bracing without jacking the top back into position, expecting the original arch will recover its original, or near to it, arch. Sometimes it does, sometimes not. The correct fix is time consuming, labor intensive, frustrating and as a result . . expensive. If I was going after a 175, I'd steer clear of any with kerfed bracing. It was a bad idea put into the build process for all the wrong reasons, as it relates to st structural integrity of the top plate. Originally Posted by rpguitar
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from FRETS.COM
"Now, in theory, these tone bars should be as strong as solid ones. The tensile strength of wood is extremely high, and if they didn't have grain "runout" and if the cuts weren't quite so deep, I wouldn't have a job to do in here."
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Here's a great reference for wood grain runout, as well as the reasons for grain orientation, and the whole gamut of considerations in guitar construction.
Guitarmaking: Tradition and Technology by William R. Cumpiano | 9780961873707 | Hardcover | Barnes & Noble
C.F. Martin IV refers to Cumpiano's book as the "Bible" of guitarmaking. Cumpiano states much of the same as the Frets.com article, but also the other determinants in brace carving.
The reason orientation matters is largely do to mitigating "movement", in addition to all the other concerns like strength. Most species of wood change in size with seasonal changes, and dramatically more so in regard to the flat sawn/split surface than the quartered surface.
Another thing to keep in mind that (whether we're speaking of curved, tapered, or scalloped braces, or even carved top/back plates of a jazz box) once the piece is contoured, the maker has force grain runout upon the wood. So, even with split wood, the concavity of the scalloped portion of a brace, or the falling arch of a top/back plate mandates the maker cut across the grain. The piece now has grain runout.
The book above is a great reference.
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From an engeneering and manufacturing point of view, the kerfed bracings are a brilliant solution!
(If they they are done correctly that is: no runouts, knots or too deep kerfings that spoil the fun....)
I am not knowledgeable enough to form an educated opinion about the influence on the sound. But especially in the guitar-scene, it's been proven that 'inferior' constructions can deliver distinctive sounds that can become classic! (Think about the Telecaster, laminated woods, etc.).
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From an engineering and manufacturing point of view . . I'm not sure it's ever a good idea to weaken something that was designed primarily to add structural support. It's not at all a brilliant solution to the structural integrity of a sound board which is subjected to considerable down pressure. It's only a solution to achieving increased profits based upon cost savings as a result of increased productivity due to time savings. That's also known as irresponsibly cutting corners to appease the bean counters. Originally Posted by Little Jay
From an engeneering and manufacturing point of view, the kerfed bracings are a brilliant solution!
(If they they are done correctly that is: no runouts, knots or too deep kerfings that spoil the fun....)
I am not knowledgeable enough to form an educated opinion about the influence on the sound. But especially in the guitar-scene, it's been proven that 'inferior' constructions can deliver distinctive sounds that can become classic! (Think about the Telecaster, laminated woods, etc.).
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I agree with Patrick. The idea of those kerfed bracings is to avoid the labor cost of the painstaking fitting of the brace to the underside of the top. The kerfing makes it possible to bend the brace to a certain extent before it breaks so it can be glued in place without the fitting. Now, that necessarily means that the brace is flexible instead of rigid. If the brace can flex, it can no longer support the top against the down pressure of the strings. If the top sags, the brace will flex with the sagging top - until it eventually breaks. Thus the kerfed brace doesn't prevent sagging - and one of the main reasons for having braces at all is lost. The brace may still disperse vibrations throughout the top, but that is hardly relevant for the 175 which is first of all an electric guitar with no acoustic tone to write home about.
As opposed to the kerfed braces of some of the 175s (not mine, luckily), my Painter laminated archtop has (non kerfed) braces which are taller than on the Gibson guitars and provides a good and stable structural support to the top.Last edited by oldane; 12-03-2014 at 03:36 PM.
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So far, this conversation has centered around Gibson 175s, but I'm curious as to where else these braces are commonly used. How common are they on Asian import guitars?
As for top sagging, I've only seen it once in my many years of playing, and it happened to an unfortunate Heritage Eagle that had been left in a hot car trunk long enough to sustain heat damage.
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I'd be interested to see if an Epi 175 has kerfed braces. I can confirm that my Terada Japan Gretsch Synchromatic 400 does not have kerfed braces.
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i think gibson probably abolished it after too many failed, probably by 1980. the japanese manufacturers probably built everything solidly.
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Never seen a sunken top, or a badly warped neck on a Japanese guitar :-)
They also usually put a patch in under the bridge between the braces. Greco does it, Washburn and I suspect the others.
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yes so does my ibanez
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My Japanese Condor ES-175 copy (70ies or 80ies I think) has no braces at all!! No sunken top (3-ply laminate), but it has a small staple under the bridge.
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I'm not a carpenter but I believe when you take a 1" deep piece of wood and saw into it 3/4" of an inch, now the whole piece is only as strong as a 1/4" piece of wood.
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It really depends upon how it is to be used. The strength is along the glued surface of the brace. Very different than the kernes brace having to act as, say, a cantilever. Kerfed braces can be just as strong as solid braces. They could even contain issues that would affect a piece of wood with no relief point - such as twisting. Think about the way it works rather than just its purpose. Could be its cheaper to not do it with CNC technology as it cuts a labor step.
bob
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