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I was wondering if anyone has tried solid kerfing like this:


what would the pros and cons of solid kerfing be. I'd imagine it would be heavier than standard kerfing and would be more labor intensive. Not sure what the pros would be.

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"All of us contain Music & Truth, but most of us can't get it out."
- Mark Twain

I would think it makes the sides stiffer. Which is good - I saw a couple of pros a couple of weeks ago advocating solid linings. I will probably be trying this in my #2 guitar shortly - as I do like the idea - and the ease of making them and gluing them. I just need to make sure I can bend them.

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It's this new idea from recent decades that everyone gets a participation award. - MUX

Pro's are:
Massively stiffer sides
Clean, smooth look.

Con's are:
You have to hot-bend the linings before gluing them in.... to match a form that is slightly smaller than your guitar body.
Some folks get around this by using woods like Willow and green ash -- which are very bendy when wet -- they just soak them in water for a while, and bend to their form without heat.

You can't bend a full thickness lining -- you gotta bend 2 or 3 pieces and glue them together to make the full 1/4" thickness... unless you are using a super-duper bendy wood like Willow or Oak....

If you want to try out something that is closer to this, but not 100% solid -- try out Reverse kerf linings.... You glue the cut block side to the guitar sides and the un-broken spine side is facing the inside of the guitar.... Cap with veneer if needed.....

Thanks

John

Solid kerfings is an oxymoron: they should be called solid linings (as opposed to kerfed linings…).
The added rigidity of the rim is IMHO overrated, once the plates are glued and form a box, I would think the hypothetical benefits are greatly reduced.
They look cleaner and do not need to be as wide as kerfed linings as the glue joint is not interrupted by the kerfs. Easy to realise on an archtop or classical "flat" rim, much harder on radiused or arched plates. I think Burton has a neat tutorial on how he does it somewhere on the OLF. Needless to say they need to conform pretty tightly to the rim, especially with a cutaway.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

yeah I realized the oxymoron after I posted, but then I wasn't sure what to call them

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"All of us contain Music & Truth, but most of us can't get it out."
- Mark Twain

This is one of those things that are often misinterpreted . Reverse kerfing and solid kerfing do nothing to stiffen a side. They will make the side more rigid to bending . In plain words , the bend will be locked but the actual side stiffness remains the same .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I always use solid, laminated, linings on all of my guitars, steel string and classical, I like the look and I like the stiffness that they give to the sides.

I make my linings in forms and use 4 or 5 layers, usually of cedrela, spruce or mahogany, though if wanted the inside layer can match the sides for a very clean look.





Once the linings and the head and tail blocks are glued in you can throw the mould away if you want, the laminated linings give the sides their fixed shape.





Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I recently started using solid linings. I find I am able to bend on the regular pattern, two sets of six stacked upon each other. I've become worried about the stress rise issue and also about repairability. If for any reason you needed to replace any part of the linings it would be very difficult. Though I don't know how often that comes up in the repair world.

I recently completed 2 classicals using one piece solid linings (Paulownia wood)....

Pro's and con's...linings need to be pre-bent accurately if using solera, notching for back braces seemed cleaner/easier. Regarding sound differences, I cannot comment as both guitars were built with same woods, simultaneously....IMHO sound xlnt....not sure how linings attributed to sound, but have/had read various literature on benefits to solid linings on classical guitars.....

Will I use it again on classicals?...probably. Steel string? probably not. Good luck!!!!

??


From the Oxford dictionary:
stiff (stiff)
Pronunciation:/stɪf/
adjective
not easily bent or changed in shape; rigid:

Solid liners do add a lot of stiffness to the edge of the sides _before_ the top/back are glued on. That's one good reason to use solid liners on the back of a guitar that's being built on a solera: they hold the shape of the back edge while you're shaping it to fit the dome of the back. Reverse kerf liners work almost as well that way. Once the plate is glued to the sides it's hard to see how solid liners could add much stiffness. I'd love to see actual measurements.

kerfing and solid lining will add both strength and stiffness at the glued on area . The actual side strength will not be altered beyond the glued area. The reverse kerfing and solid lining will lock the shape and this make the bent side feel more rigid but this would be made fixed once the top and back are glued on.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I have been using them for a couple of years. At this point most of the guitars I have made have them in some form or another. I started out wanting them because I thought it would stiffen the sides and make them more "solid". At this point though I can't say that for sure. It does make the rimset much stiffer (and locked in place) and I do like that a lot but the argument that gluing the top and back on does a similar thing makes a lot of sense also. I do notice that when I rout for the binding nothing changes in the way the box responds. Well, maybe not nothing but nothing like what happens when you do the same procedure with traditional kerfed linings. The binding is not acting as much as a structural part of the guitar as it is with a more traditional Martin style build. Beyond that it is hard for me to say what it is doing. I do think it looks really cool but I also think a well done kerfed lining looks nice too. How is that for a waffling answer?

I did do a tutorial on how I do mine. It is here:
viewtopic.php?f=10117&t=21455

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Burton
http://www.legeytinstruments.com
Brookline, MA.

As I see it, the big advantage of the stiffer side assembly possible with solid
linings, reverse-kerf linings, laminated sides, or any other method- is precisely
that it doesn't rely on the top or back plates to stiffen the structure, or I should
say, not as much. The plates can then be optimized for their primary, acoustic
function, with less concern about their providing structural integrity. In particular,
cracks along the grain on the top, caused by the end block wanting to
move toward the head under string tension (in other words, the sides attempting
to widen under this load) could be lessened by a stiffer rim assembly.

I also have started making/using solid linings. The method I use is pretty much the same as Colin's. I don't know about any advantages/disadvantages - just like the way they look.

Max

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Max Bishop
Brighton, Michigan

Exactly my thoughts. I do not believe the linings affect the rim stiffness once the box is closed, unless they're made extremely tall (à la C.Fox). Laminating the sides, OTOH, make a noticeable structural change.
One feature I borrowed from Rick Turner is to use "side doublers", essentially a .070"-.080" lamination roughly twice as tall as the linings on the top side. It works, and where it counts. I do it like this on larger guitars:

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Regardless of what lining / kerfing you choose , the top will still expand and contract and the stresses to the top will be present through RH swings .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Personnally, I don't believe stiffer sides to have such a impact. Or if you take it the other way around, that more flexible sides are that bad. Since I can 'flex' my sides with simple finger pressure, it shows that the force required by the top and back to keep the sides in place is minimal, at least compared to the several pounds of pressure the strings put on the top.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

It removes the sides from the equation, which allows the top and the back to do their thing, un-impeded.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

The sides have the same surface as the top, or the back. I really doubt they do not affect the sound, especially in a old style Spanish guitar where they tend to be thin. Laminated sides are great for a certain type of sound but I wouldn't try them when going for the light-guitar-that-works-as-a-whole.

Laurent, I have been thinking about the same partial lamination for when using extra wide purfling, and was so close to doing it on my latest guitar, but in the end just cut wider linings. I will try it eventually next time

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Build log

Burton Legyt wrote:
" I do notice that when I rout for the binding nothing changes in the way the box responds. Well, maybe not nothing but nothing like what happens when you do the same procedure with traditional kerfed linings. "

When you rout kerfed liners for the bindings, you make a lot of leaks around the edges of the plates that vent the air resonances, and add a bunch of drag in the process. Solid liners don't make leaks when they're routed. If you tape off the rabbets you'll find that most of the sound comes back. Routing the bginding rabbets does reduce the edge stiffness a bit: the top and back modes, particularly the 'main top', drop in pitch.

Carey wrote:
"As I see it, the big advantage of the stiffer side assembly possible with solid
linings, reverse-kerf linings, laminated sides, or any other method- is precisely
that it doesn't rely on the top or back plates to stiffen the structure, or I should
say, not as much. "

Ah, but the point is that you get that added stiffness anyway. So long as the glue area of the liners is sufficient to keep things together, the form of the liner should not effect the stiffness enough to matter.

I'll note that the mass of the sides/liners could well have an effect. Some energy is passed from the top to the back via the air in the box, and some via the motion of the sides. Adding weight to the sides cuts down that motion, and reduces the amount of energy transfer, in the experiment I ran.

Alexandru Martin wrote:
"The sides have the same surface as the top, or the back. I really doubt they do not affect the sound, especially in a old style Spanish guitar where they tend to be thin."

The curvature of the sides stiffens them up a lot. I've looked for Chladni patterns on sides, and generally the only area that forms them is the more or less flat part below the waist, and that's often up around 500 Hz. Side vibratino probalby has an effect on the higher frequency stuff, but that's pretty hard to look at. Those little Rennaissence instruments, with the fairly flat, deep sides, might get some sound out that way.

Then maybe what the light sides (and back) do for the light guitar, is to push up the top pitches, or rather, help the guitar stay in the reasonable interval even with a very light top? An overall "lower" impedance? I guess this could be easily checked by attaching weights to the sides and/or back and then see how the pitches move?

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Build log

That is my thought as well. The stiffness added by gluing the back and top plates in place is much higher than the stiffness added by either a solid, reverse, or traditional liner. Another point is that once the top/back is glued in place.......no way to have it not add stiffness to the structure and rely on the stiffness of the liner instead. Seems the primary purpose of the liner is to provide sufficient glue area for top and sides to remain intact. As long as the liner doesn't split, or the glue fail, or the liner deform.......the mechanical properties of a "box" shape provide stiffness in spades. The stiffness of the liner seems negligible in comparison. I guess minimizing the chance of splitting could be an argument for a laminated liner. Possibly it's as easy to laminate a liner as to saw the kerfs in the liner.

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Formerly known as Adaboy.......

I'd have to say that the jury is still out on whether the mass and stiffness of the liner can have some acoustic effects. It is entirely possible that the impedance of the liners has an effect at higher frequencies, so the differences people claim to hear could be real enough, although I suspect they're 'small'. This sort of thing is hard to test in any reliable way. The bottom line for me is that I don't think much about the stiffness or mass of the liners, compared with how well they glue, but if you like the way gheavier or lighter or less or more stiff ones work for you, go for it.

I think we should call them kerfless linings!

Just my two cents: reverse kerfed linings. Love the way they look. And smell if they are SC.

Mike