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OK, a comment about Shan'es Moral stance on not wasting the great resources that the Lutz trees are struck me.......

coupled with the fact that I'm tighter than a duck's behind......

Has anyone other than McPherson tried Laminated braces?

surely all those offcuts from the edges of soundboards should be used.......

lammed up to make braces.......

McPherson bracing link.....



or am I talking rubbish again?

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Lots of builders use laminated braces. Infact i have intentions to soon my self

OKaaaay then,

are we cutting three 1/4" strips off the outside on the jointed top, sandwiching them, then turning them 90 degrees so the lams are vertical like the McPherson?

or should there be some change in grain in the middle lam rather than having tham all parallel?

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I assume you plan to CF for the middle lamentate. I would want the grain of the CF running just as you would if it was a non laminated spruce brace. This would be perpendicular to outer laminate. Just as shown in the McPherson photo. The stiffness of the brace is now coming from the CF.

If not using CF for center laminate the you still would want the center laminate grain to run perpendicular to the outer laminate

If not mistaken, why before McPherson (by way love their guitars) the Larson Brothers, who made Prairie State, Maurer(sp) and other brands way back. These guitars are very comparable if not better than older other name brand of the day. Hard to find, but fine instruments. Stefan Grossman has one and the sound is great. I think also had a metal bar that ran legnth or the box. These were not cheap and very desirable from what I have heard for collectors. May be wrong, and subject myself to rebuke if I am.

that should have been way before McPherson not why. seen it and couldn't stop before the post.

[QUOTE=ToddStock] ...... what does it bring to the design?[/QUOTE]
That's the question.
The thing that carbon fiber brings is more stiffness, less weight, and more stability.
I don't think our spruce braces aren't stiff enough, are too heavy, or too unstable. If anything, they are too stiff and too heavy because they are too big. If we make them smaller, (taller and thinner) they'll be light enough and stiff enough.
That's my take. YMMV   

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

It looks neat, as well. In the world of production guitars, 'looks neat' is a big seller.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

One reason for using carbon fibre in braces is the material's lack of 'memory', it will not take a set over time like wood can. That means they will help the top maintain its geometry over time, where a top with solid wood braces may deform permanently.

[QUOTE=ToddStock] Mmm...is there a valid reason to use CF in this orientation? Seems like a cap laminate is a much better approach to using high modulus materials. Other than the 'looks cool' factor, what does it bring to the design?[/QUOTE]

By capping, do you mean a layer of CF glued to the bottom (facing into the box)? That makes sense in theory, it would be like the flange on an I-beam, but it sounds difficult to glue, carve, not to mention 'tune' such a brace.

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Rian Gitar og Mandolin

In my experience, it is easy to make a brace laminated with CF stiffer than wood but it is hard, maybe impossible, to make it lighter given the ususal gluing surface requiremnets and lateral stability needed.  Particulalry a laminated brace with all that glue.

Yes, CF has great stiffness/weight ratio but in dimensions that make sense for braces, it is way heavier than wood.  The reason to use it as a laminate that makes sense to me is because of it's memory.  With time, wood will deform under load and want to stay in that deformed shape even when the load is removed.  CF will want to go back to its original shape when the load is removed and as a result, may keep a lightly braced guitar from deforming as much over time.

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Like Steve said less weight for a given section modulus is the thing CF offers. I very well could be wrong on the best fiber grain orientation for CF in a laminated brace. Intuitively i would think you want the center laminate CF's fiber structure running just as you would have a solid piece of spruce running. but I will admit I could be wrong here.

I think you meant to say parallel to the rest of the grain in the brace, rather than perpendicular, and that's what led to all the confusion.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Not if you are using top cut offs as shown in the Mcpherson photo. If you are using brace stock for the outer laminate the yes the would be parallel.

Now I'm confused. It looks to me like all the grain in the photo is going horizontally, just like a normal brace. Are we looking at the same photo?

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Look again Bob .. thru the cutout in the overlapping brace ..the grain line runs thru the cut PARALLEL to the top - its a flatsawn section - we use braces oriented for quarter. These are top cutoffs turned on their sides - thats now a flatsawn piece. They need the centre lam to give these strength - or keep them taller as well, as its obviously the worst orintation to get strength out of spruce.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Humm?????? I believe they are using Rosewood for the center laminate not CF. There whent the weight savings

I'm doing the 'Mario Thing' on my next guitar, namely laminating (like that picture) a 0.02" sheet of unidirectional CF between two strips of (traditionally grain-aligned) Adi spruce. A cap will add more stiffness, I'm sure, but I'm doing it to decrease the spruce's memory effect more than anything else, at a minimal increase in mass that should be easily compensated by a little carving (should it be necessary). I like how wood looks, how wood instruments sound, and I'm not trying to go full-on innovation style (I'll let folks like Rick Turner trailblaze while I figure out slightly more 'basic' things), but decreased memory's a plus. Mario's description (it's in the MIMF library) of 'abusing' various scraps of spruce brace stock with and without CF by hanging weights, exposure to heat, humidity, etc., and the increased resilience (springing back into shape isntead of taking a set) of the laminated bits pretty much convinced me to give it a shot. Have a small section of laminated stock I've hung a little weight on as well as a control. Only had it for a few months now, but the results are much like Mario's.

I've been using laminated braces for several years in the Kasha-Klein braced guitars I've built. Two braces in particular I laminate are the yoke braces that are attached to the neck block and the "flying brace" that anchors in front of the bridge and terminates at the top of the waist. These braces are made from multiple layes of maple veneers CA'd together in jigs I've built (they are curved). The only place I use carbon fiber is in the yoke brace. My rationale for this is that I do not want to stiffen any brace beyond the amount necessary for it to perform it's function.

Kent has made a good point about the weight of the carbon fiber. There is a misconception among some who think that carbon fiber is light. Relative to steel to which it is often compared, it is, but relative to spruce, it is pretty heavy and IMO, the "memory" chracteristic isn't necessarily a good thing for a soundboard brace. It seems to me that any material that is resistant to movement will impede plate movement and that's not good.

There are plenty of schools of thought on this, so I know some will disagree. The common sense alternative to me for those who are concerned about weight is to simply laminate spruce. A laminated spruce brace comprised of 2 equal thicknesses is stronger than a single piece and weighs the same. I've been doing this on upper transverse braces and it works very well.

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Jimmy Caldwell
http://www.caldwellguitars.com

And what adhesive would someone use to laminate CF to brace stock, epoxy?

Thanks.

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Arg, you're totally right (Tony and Mike). For some reason I was interpreting the statement as implying the center lam should be set in as all short grain, like one would do when laminating sides together, and it just made no sense. Too many perpendiculars in three dimensions.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

People who ride road bikes and mountain bikes understand real well that CF has 2 important characteristics -
1) Strength to weight ratio.
2) Stiffness.
3) Vibration dampening.

The vibration dampening is very real. It does a great job of smoothing out the ride. It is used for frames, handlebars, forks, seat stays, stems, etc.

Just a guess - the high vibration dampening characteristic might not be the best thing in most steel string guitars.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

The amount I'm talking about (and Mario uses) is really pretty minimal, and in terms of 'tap tone resonance', I don't hear huge/significant differences. Certainly not in terms of damping and/or ring, although I'll do a little more testing when I get the big stuff laminated up (X-braces, which is where I'm using it). Keep in mind I'm talking loose sticks of binding right now, not the easiest things to tap. The goal is to add enough CF to get rid of a memory effect, and longer term deformation (ie, bellying), not to add massive amounts of stiffness, if any at all.

We put CF in necks, after all, and I like what it does to those (mine resonate longer and at a slightly higher pitch, good sustain, after I glue the bars in compared to before gluing in the bars. It's selective stiffening that affects the main vibrational modes, but for necks at least, it does it in a way I like.

Anyway, I'll shut up about it now until I've actually finished a guitar with CF braces in it.

[QUOTE=ToddStock]
As for cool? I personally think a nice composite bowl-shaped back, a raised rosette made from mother-of-toilet-seat, and a single-piece cast aluminum neck would be oh-so-mega-cool...[/QUOTE]

Humm???? sounds like 1977 model Applause. you need one