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It seems to me that the extra stiffness of reverse kerfing becomes inconsequential once the top and back are installed. Since I do not remove my rims from the mold untill after the plates are installed the extra stiffness really makes no difference to the final product. I do however like the idea of the kerfing being flexible in both planes, and I think I'll try it on my next guitar.

Al

I am not the most qualified guy to talk about the what and why for's, BUT....

It seems to me that you want the rim to be like the sides of a drum... Rock solid. Anything you can do to stiffen the sides will yield a better instrument. You don't want energy loss into the sides.

I really hate raining on Bruce's parade here because I DO think the idea is very clever, but again IMHO (and I might be wrong, but that's my story and I am sticking to it) you want the sides as stiff as you can get them. And weakening the linings so they flex in a vertical plane HAS to weaken your rim... glue or no glue.

Brock Poling38910.8277083333

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Brock Poling
Columbus, Ohio
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I'm game to give it a try. So Bruce, when you gonna start selling Bi-flex kerfed linings?

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Don Atwood
Arlington, VA

Bruce, it's a great idea! I've tried, in vain, do figure out a way to make mine bend in the 3rd dimension as well.
You know my opinion about stiffness so I won't bore you with that. One thing I did do this week in Montreal was sort of a stiffness study. I played LOTS of guitars. Some braced very stiff and some braced very light. (this is backs and sides only). And I found that the stiffer braced guitars projected better. I'm not sure if this was a true apples to apples study as I didn't take top bracing into account. But I think it helped support my theory that the tighter the boat (sides and back), the faster the sound waves are bounced out of it and thus creating more volume.
But I don't think you are losing anything Bruce. Once they are glued, I think they will be equal to standard linings as far as stiffness goes. Great thinking!

You could easily make it a lot stiffer if you bonded a .025" thick strip of mahogany after it is attached to the rims. Leave it a little proud and sand it off in the dish. It would have a very solid look from the sound hole and cover any extra glue.

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[QUOTE=SteveS] You could easily make it a lot stiffer if you bonded a .025" thick strip of mahogany after it is attached to the rims. Leave it a little proud and sand it off in the dish. It would have a very solid look from the sound hole and cover any extra glue. [/QUOTE]
Except that you would have to find a way to grind the top and bottom of the strip since the kerfed strip has been manipulated in the z axis. That's the major problem I'm having in doing something like this.

[QUOTE=A Peebels] It seems to me that the extra stiffness of reverse kerfing becomes inconsequential once the top and back are installed. Since I do not remove my rims from the mold untill after the plates are installed the extra stiffness really makes no difference to the final product. I do however like the idea of the kerfing being flexible in both planes, and I think I'll try it on my next guitar.

Al[/QUOTE]
Well said - I very much agree with this.

The real stiffness and strength of a guitar box comes from the plates and sides working together. Each is very stiff in its own plane, and very flexible out of plane.

When combined, the joint is very stiff in every direction. The kerfing ties them together so this happens, but the bending stiffness of any kerfing is negligible compared to the plates/sides combination.

To understand this, think about how stiff the completed joint feels - push on the binding of a finished guitar with your thumb and see how much flex there is. Compare this to a piece of kerfing by itself. (or, even glued to a side)

But, before the plates are attached, the type of kerfing will make a big difference in the stiffness of the sides/kerfing combination, so, the kerfing stiffness may be important from an assembly standpoint, but not in the final product.


Phil

And wouldn't that type of lining allowing the top to vibrate more freely? Isn't it what we're looking for?

One option could be to use traditional linings between the back and the sides and the flex ones between the top and the sides, the drum effect like Brock mentionned would still be there!

I think the top vibrating more freely depends on how solidly it is joined to the sides. I feel an over kerfed lining will dampen the vibration like a sponge. Just my 2 cents.

Just out to the edges Serge. You want to top to vibrate, and the sides and back, but the top is realy the one you want to move the most.

Where is Al Carrath, I'm sure he's done about a million tests on this

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Good idea Rod, and also, if anyone dares to experience it, please let us know!

What's really needed is to be able to flex the linings through a fourth dimension, creating a superspherical brace. I used to think this required passing a three dimensional lining through a klein bottle, but this new idea has shown me the way to start with a mobius lining strip and notch the mobius kerfing along two more dimensions so that it will get that fourth dimensional flex. Since sound is round, this will produce a hypersonic instrument. It might be a bit dangerous to play such a guitar here on earth. Any reverberation in the hyperspace medium could cause waves that increase exponentially with each cycle, opening fault lines and causing enormous tides, before eventually ripping the planet apart. It should be safe to test in space, though. Hypersound in a near vacuum will lbe dampened in one of its dimensions, and just sound like a really loud scratch of fingernails on a blackboard, if my calculations are right.

Clever idea, Bruce, and proof that you have passed into the incurable stages of this disease. Please remember to donate your brain to science.Howard Klepper38911.1399768519

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Howard -

Bruce - very cool idea. I'm gonna try it. I suspect Phil is right about the stiffness of the lining being negligible compared to the plates/sides combination.

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Todd Rose
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I think Howard eluded nicely to the fact that we're taking the binding thing WAY overboard. Say what you want about stiffer rims and laminated linings etc., but when one goes and looks at some of the finest guitars being made today, they aren't using that stuff, a lot of them are using traditional triangular linings, and they are getting great sound and projection. Just call Collings, Borges, Bourguois, Tippin, TJ Thompson, etc. Ask them what they use and why.
One feature like this type of lining or that type doesn't make or break a guitar. Look elsewhere.
I know we'd like to think there's some mysterious Holy Grail of linings, but it's relatively inconsequential. Bruce's idea to make it more flexible in a vertical direction is very good. Once it is glued to the top and back, the total structure is basically the same in all cases.
Kerfed linings, or individual blocks have been used for centuries. Their sole purpose is to provide a larger gluing surface for the top and back to the sides, without adding too much mass.

All this debate over linings is kind of silly.
You need them...so if you can make them a bit more easy to install, I say go for it.Don Williams38911.3079050926

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[QUOTE=Don Williams]
Kerfed linings, or individual blocks have been used for centuries. Their sole purpose is to provide a larger gluing surface for the top and back to the sides, without adding too much mass.

All this debate over linings is kind of silly.
You need them...so if you can make them a bit more easy to install, I say go for it.[/QUOTE]

Don, interestingly on lutes we don't use any linings at all, the top just gets glued to the small head and tail blocks and to the 2mm thick sides. I've seen 300 year old lutes where this joint is still holding up just fine. And, clamping the top to the shell is not possible, has to be done with roping or just tape. I use triangular linings on guitars now and even thin those down.

Colin

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I'm with Howrad, except I want 5 dimensional purflings. Really, I use shop made reverse kerf linings, at about 3/4 tall. I start at the neck block, with the linings about 1/8 inch higher thant the sanded rim - dont twist them as you glue on - the added height here will be just flush as you approach the waist area. then the excess gets sanded off. Yes the linings are now uneven in height, but its a gradual thing, and it looks fine - no one has ever complained about the look of the linings, besides, how much of them do you really see ??? I ask the same thing of folks about the tail wedge of their current guitar just to raise a point - most people seldom if ever really look at it.

So in conclusion, putting in linings is really pretty easy. I bend them dry to shape in the rim with a heat gun to prevent breaking on tight curves - still happens sometimes though.

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Tony Karol
www.karol-guitars.com
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I do it pretty much the same at Tony except ill soak them in a sink of warm water for about 30 seconds, then damp them off with paper towels and blow out the water in the kerfs and go stright to the sides. I rarly if ever brake them.

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Lance@LuthiersForum.com

If you are using the standard triangular linings, just use a box cutter to cut partly through the back side near the waist, or any other high bend point (like a cutaway). This will allow you to fit the lining easily in the 3rd dimension bend.

I do think that linings can affect sound.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.