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Pricey but kinda cool. http://dragonplate.com/ecart/categories.asp?cID=130#buy

Anyone here try it yet? I think I'll pick one up on the next order just cuz.

Looks cool, but pricey! I'm still skeptical about leaving out a truss rod. I've seen a lot of guitars come in for repair where I wish they had a truss rod.

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Josh House

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You can make your own and still embed the rod in there-



I've gone in and added the top connector back in too, it can still all fit.

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

How does one go about making their own? That's totally cool....

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Old growth, shmold growth!

Excellent piece of workmanship Burton, don't think neck will be moving to far any time soon.


Steve

If I recall correctly, Burton did a thread where he showed his process. Might do a search for it.

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Steve Smith
"Music is what feelings sound like"

Couldn't find it.

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Old growth, shmold growth!

I tried to find it too and couldn't. No telling where I saw that. Perhaps Burton will chime in with a link.

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Steve Smith
"Music is what feelings sound like"

Hey guys-

A few pics in this thread plus some very good advice from Stuart (which I took-)

viewtopic.php?f=10101&t=40265&hilit=legeyt


I don't have too many other photos of the process but if you are interested PM me and I can describe it. It is pretty simple.

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

Has anybody come across a guitar with a CF truss that needed adjustment? Is CF THAT stiff so adjustment would never be needed?

I am using a D-Tube for the first time in a slope Dread that is near completion. I am impressed with how light the neck is. I made a holding device to which the neck was mounted and glued a cheap bridge on the holding device at the correct string length for the neck. Strung it up to pitch and waited 5 or so days for all the tension to build up. The neck is nice, old Hondo mahogany with a granadillo fingerboard. Deflection was .007" at the middle of the neck at full tension. I put an additional .004" scoop in the fingerboard so that the relief would be .011" at pitch.
If I use a D-Tube again I will figure the amount of weight to hang on the bottom of the holding device to simulate string tension. This method of applying weight to simulate string tension is common in the classical world where truss rods are the exception rather than the rule.

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Stay with the happy people.
--Reynolds Large

Yes...it's very stiff but that depends an awful lot on how it's designed for use and how well it's processed.

Burton's D-cell application is a near perfect application of carbon fiber...provided it's a braided weave and the fiber is NOT oriented at the 0-90 degree bias relative to the neck length axis. The carbon fiber in that design will add both longitudinal AND torsional stiffness and will mitigate the effects that humidity may promote over time.

I'd ALWAYS want a truss rod though. The backbow created by fret installation is dependent on fret slot width relative to the fret tang and fretboard wood hardness. The carbon fiber will also mitigate that effect...but even with a proper carbon fiber reinforcement, with those variables, it would take a LOT of experience to predict the final outcome of things.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

That is very clever Burton. Looks like a pretty simple lay up after a bit of prep. I assume you made the radius the same as a box core bit?

Danny

Danny,

Yes, I did- And the wood insert that fits inside matches a roundover bit (in 2 passes). It leaves a 1/16 thick layer of CF which can be up to 7 layers depending on the weave.
Per Stuart's advice I have been using a braided weave as the core of the CF layer with unidirectional fibers (run along the length) on the top and bottom. When I cap the U (to make the D) it is braided (think 45 degrees crisscrossing along the whole length) material that attaches itself to the vertical walls and then I cap that with another layer of unidirectional. Probably better if it all wrapped around but according to my MIT friends it does still make a difference at the ends of the stress level (questionable whether a guitar neck will ever come close to reaching that of course-)

You can see a particle board piece in the pics too, that is for running it through the thickness sander after glue up and trimming. It leaves a very clean insert and the thickness sander's excellent dust extraction makes what would be nasty a little cleaner.

I did one recently with no rod and added a vertical strut. I'm not sure it is doing anything but theoretically it was like the union of a T bar and the U shaped reinforcement. The customer was very interested in some CF T bars TJ had been looking at so it made sense to add it in even if the U is doing most of the work. Here is a pic of that:



Stuart is again right on with the issues with a non adjustable neck. For this one I had fret saws custom ground to match the solid part of the tang on the fretwire we were using (purchased and measured-). Then I filed off the barbs and glued them in. This is again inspiried by some barbless fretwire TJ was looking at. I bought a few pieces to check it out, a bar fret type install but with a rounded top. The extrusion was much thicker than normal. It was pretty nice.

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

Very elegant stuff Burton. I do have a question.

I've been using the usual two 1/8" X 3/8" carbon bars on either side of a 1/4" (Blanchard) truss rod. Run across into the headstock (Slothead issues noted!). Conventional fretting with hide glue in the slots. This has never failed to give a neck of adequate stiffness. In many cases I need to put some reverse tension on the rod at initial string up and usually level before fretting with some tension on the rod to avoid that. I've seen the instruments 8-10 years out and the stiffness is maintained without much if any truss rod adjustment.

Your very elegant approach is a ton of extra work including filing tangs off the frets and gluing. What benefits do you see that justify all that extra work?

Although I have a heavily built "75" D28 without a truss rod that has been totally stable all these years I must admit that the absence of a truss rod in lightly built boutique instruments like yours makes me a bit nervous.

Thanks

Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I've done a Gibson style solid neck with a V shaped hardwood insert on one instrument (lightly built parlor for a friend's kid, meant to be strung with silk and steel). I've thought of doing something similar on steel string builds only adding a 1/16th or so layer of carbon fiber to the walls of the V. I'm sure it wouldn't be nearly as stiff as Burton's U but seems like it would be a bit quicker (at least initial set-up wise) since both the V and the insert can be quickly cut on the tablesaw and I'd think that the CF could be layed up in situ.

Anyone have any idea how something like that would perform?

Hey Terry,

The benefits? I'm not sure I'd have a satisfactory answer- I like the details. I don't think anyone will ever accuse me of working fast and I'll never pump out guitars but that is not what i'm interested in. If the details don't take a ridiculous amount of time and/or cost/effort then I am glad to do them.

The easy answer is that I think a guitar without an adjustable rod sounds and feels better. There are still bar fret Martins that have held up great. It IS possible to do and if I can do it without sticking a big piece of steel in there I am into that, especially since it allows me to build very lightweight bodies and have a physically balanced instrument. That is tough when you add the rod in. My last OM (BRW/Adi) was 3.5 lbs. with strings. That guitar with a Blanchard (or similar) rod would have been neck heavy.

As you said, just adding 2 simple bars works pretty well. But, could it be better? I think so and that is an area that interests me.

I don't build without the adjustable rod all the time, it takes a very specific customer to understand what it is about and they are usually into vintage guitars and already have a bias. Most of my guitars do have adjustable rods. But- I build them like they don't. I am happy if that rod never gets touched and I'll do whatever work I can so that I don't need to touch it when setting up the guitar the first time or the hundredth.

People always say that they don't have time to build enough guitars without truss rods to understand how to build that way. Having the U shaped reinforcement gets me the best of both worlds. Customers feel reassured because the big old paperweight is in there and I get to "practice" building a non adjustable guitar every time. Well, it maybe isn't that simple but it isn't that far off either.

I don't think of my guitars as lightly built in the way I think you mean. They don't weigh much but they are built with strength and resilience in mind throughout the whole thing.

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

Thanks Burton, that makes total sense. I really admire what you are doing.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Burton, in looking at the associated thread, my question is how do you go about dimensioning/cleaning up the plug on the thickness sander? The other question is whether the cost/time of the materials is less/more than using pultruded bars?

David, I'm only dealing with the height of it on the sander. Out of the mold there is some excess that needs to be cut and sanded off. I have a bandsaw with a modified dust collection to do that work. It's not much, though. I use an aluminum caul and peel ply and most of the insert is ready to go once the ply is removed (and the peel ply creates a perfect surface for bonding into the wood channel). Its mostly the upper edges (excess resin and carbon) and cutting the ends to length.

Its obviously more work/dollars than simply buying bars but once you have the process worked out it really isn't bad. Stuart recommended a manufacturer for the braided CF and it was an industrial type supply place so the "sample" pack they sent me will make 10 or more inserts. Even if I paid for it it is not that much more than buying nice bars. The resin wasn't that expensive either and you really don't use much. I am using an AVT resin (can't remember the exact product number at the moment) with a TETA hardener based on recommendations from people making CF tubes. It dries really hard. Time is more the issue but even that isn't bad. If I was making a ton of guitars I could make a couple of years worth over a week. And if I spent a bit of money and made more cauls I could pump them out fast.

Making the aluminum caul is the part that I imagine would be problematic for most people. It doesn't need to be aluminum but it is nice to have one that will last and last. All you need is a mill or a friend with a mill and it takes no time to run a round channel down a bar.

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

DennisK,
Thanks for posting this link in that other discussion.

Burton and Stuart,
Would there be any disadvantage to using the neck and the wood core as the mold? Seems like you could save some steps and have a perfect fit.

Steve

When considering composites EVERYTHING is simpler in theory. Yes...it would save you a step to laminate the wood and composites together in the same clamping operation.

Once the material is wetted out, however, handling becomes very difficult. A LOT of thought has to be out into every aspect of handling the materials prior to, and during the molding process. This application, a long narrow strip compressed into a groove, might seem simple but the first time you try it you'd find that vertical walls would make it quite difficult to do at all....and then after that....to get a consistent result.

If I were to try this I'd design angled walls for the groove. Not a U shape but more of a V. With cnc stuff...this is easy enough. Without cnc I would think the amount of prep work required to produce a good, consistent result wouldn't be worth the benefit. Practicing would improve how things work out. I'd be making about 5 or 6 little test articles to prove the concept and practice a buch before I'd even think about a neck.

When laminating composite to wood cover both wood surfaces with resin after wetting out the fabric.

You also have the problem of having to overbuild the fretboard surface by quite a bit in order to be able to shave it down to the point where the wood and composite are flush. The gooey mess that makes things difficult has to be considered here. You'll need wider margins than you think.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Yes to what Stuart said.

You could do it but it would be a mess and maybe that is okay- I never considered it as a realistic option.

I have not had an issue with the vertical walls problem with the U shape. It takes some care selecting how many layers are needed and I am not being super anal about fiber density. I want to have to force it in but not with monster force. As long as the line is visually consistent when cleaned up I am happy.

If you mill out your mold with the same bit you will use to mill the neck you don't really have to worry about the fit. Also, the peel ply in the original glue up should give you a _slight_ gap which should be about right for epoxy when you put it in the neck. Mine feels snug when installing it.

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