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Graphite Neck Reinforcement?


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You can use kite rod tubes. They're more flexible than the square rods, but probably achieve similar results. I've used 6 mm tubes --bought them at the sporting goods store, cost me 5 euros for a 1.5 meter rod.

I'd wondered about this a number of times as i've got 5/6 length's of 3mm solid x 1.5 metre hanging around. Hmmm....think i'll get some cheap softwood and have a play as, as you stated, the stuff's a tenth of the price from a kite shop compared to anywhere that has the word 'guitar' in it's business title.

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You can use kite rod tubes. They're more flexible than the square rods, but probably achieve similar results.

Kite tubes are definitely more flexible....and since the function of carbon fiber rods is to stiffen the neck, this means they most definitely do not achieve similar results. Use the solid rods with rectangular or square cross-section (depending on your finished neck thickness).

BTW a lot of folks like to claim that CF rods make the neck lighter, but this is pure fiction. The specific gravity of solid CF-epoxy rods is ~1.5, i.e. 1.5X higher than water (i.e. they sink). Almost all wood has a specific gravity <1 (i.e. it floats), so CF is more dense than an equivalent volume of wood. They are purely for stiffness, and stability as well.

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yeah - just lighter compared to the equivilent length of steel.. I notice Taylor are using spring steel bars in there necks, installed in a wavy channel to make sure they are under tension... makes me wonder what the advantages would be of this over CF bars. but they spend a lot mroe money on R & D than me so i guess they know what they are doing

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Kite tubes are definitely more flexible....and since the function of carbon fiber rods is to stiffen the neck, this means they most definitely do not achieve similar results. Use the solid rods with rectangular or square cross-section (depending on your finished neck thickness).

Myka uses them, which was good enough for me!

He doesn't use them for the sole purpose of adding stiffness to the neck. The other reason for using carbon fiber reinforcement is to eliminate dead spots --since carbon fiber bars AND a truss rod are probably overkill simply for adding stiffness to a normal electric guitar neck. Probably in a bass guitar neck too --how many times do you see a bass player have to tune up during a show?

But you're forgetting that, while the tube itself is flexible, once it's epoxied into its channel, it becomes something else. And definitely it's more resistant than wood, since it's immune to temperature and humidity changes. And I think the added resistance is a more interesting property than stiffness.

As for the lightness-- the kite tubes are hollow, so that's air instead of wood (and the tubes are definitely not heavier than the equivalent length of wood).

Now, as to whether they're really necessary? That's hard to say...

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I too have some spare kite spars in the garage from my former days designing and building stunt kites, and they are very flexible: they are meant to be. I'd be happier trying to find a propoer solid pultruded section, square or rectangular beam, than a cf tube, to really aid stiffening the neck.

Luthiers Mercantile have them but again its hassle and cost getting them in from the U.S.

http://www.lmii.com/CartTwo/Secondproducth...ds%2FNeck+Parts

There MUST be somewhere closer to home doing pultruded beam sections!

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But you're forgetting that, while the tube itself is flexible, once it's epoxied into its channel, it becomes something else. And definitely it's more resistant than wood, since it's immune to temperature and humidity changes. And I think the added resistance is a more interesting property than stiffness.

What other kind of resistance are you talking about? Resistance to bending IS stiffness.

Sure, an air-filled tube is lighter but consider that, even with a round-bottomed channel, you're still filling space around the tube with epoxy. Now is that combination still lighter than an equivalent volume of (say) maple? Probably. More stiff? Debatable....definitely less stiff than a solid CF rod.

Then there's stability (stiffness over time), there I'm certain a solid CF rod wins.

There are plenty of guitar and bass necks with CF rods, even on acoustic guitars.

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There are plenty of guitar and bass necks with CF rods, even on acoustic guitars.

I used them on the last builds just because... there's a definite difference in the stiffness of the neck though. I think I prefer the more supple feel of a regular style neck, so the next one will be built without --but since using a square rod would add even more stiffness, I don't think I'd like that at all. Maybe I'll have to build a neck with those one day, just to find out.

So yeah, I look at using the kite rods as a mid-ground between the square rods and no rods.

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Try RC model planes shops. That’s were I get my CF rods and sheet stock

Instead of bars you can also try using:

http://www.lmii.com/CartTwo/thirdproducts....ite+Sheet+Stock

laminated between the neck laminations, going right through. I did a "scientific" test run between laminated necks without reinforcements, laminated necks with bar reinforcements and laminated necks with sheet stock laminated in between the layers of wood. Search and you will find the result somewhere here. At least I think that the result were pretty interesting.

There is one more reason to use CF other than pure strength. And that’s “memory”. If you bend a piece of wood and let it stay bent for a long time it will keep its shape even when the bending force is removed. CF will not do that. There was a guy over at MIMF that made long time test of acoustic guitar bracings and he reported that braces (with CF sheet stock laminated into them,) held in a bent position for three years sprang back into the original shape when released. That was not the case with the un-reinforced braces.

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Hey, if you want to share any thoughts with another Swede, give me a holler. I don't claim to be an expert, but I did use to be a mechanical engineer, and will be trying out a variety of things for neck construction in the near future. (See http://guitarworks.thestrandbergs.com/)

Stewart MacDonald (http://www.stewmac.com/shop/Truss_rods/Carbon_fiber/Carbon_Fiber.html) have shipped things just as fast (or faster) than any Swedish supplier you could find, is my experience. And with the good exchange rate, VAT and shipping isn't even a big deal.

Cheers,

Ola Strandberg

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Peter, I think your findings would make perfect sense. Are you still working with CF on your soundboard bracing?

Using a taller reinforcement will increase strength much more than adding the equivilent width. Although this is a very directional increase in strength, it should be just what we are looking for on a neck to increase resistance to string pull. Since we look to carbon fiber to add an additional element of stability do to it's low memory, there would seem to be possitive features to having strength from the CF provided in other directions. There would seem to be a combination of things to consider and from that I could see the possibility of tube stock(fairly unidirectional), solid rectangular(somewhat more directional), or full height lams and or combinations perpendicular to lams(very directional). A neck will perform without any CF added, so I think this comes down to personal choice, and what we want to achive.

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I've been looking into graphite rods recently, and am getting ready to order some. I found .092" x .220" (approx. 2.34mm x 5.59mm) solid graphite rod (in epoxy base, 21 grams / meter), in 48" lengths for around $9 each, shipped (in quantity). That's less than 1/4 of StewMac's price of $18+/24" plus shipping.

If anyone would like to go in on some at that price, let me know and I'll include it in my order. No minimums, as I'm going to order just about enough to get that price myself anyway.

There are some other sizes available too, so let me know if you're looking for something else.

Looking to get an order together by next week sometime.

[Edit: These are rectangular in cross section, not round.]

Edited by Rick500
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All of the guitar necks that I have built in the past 10 to15 years have carbon fiber in them stiffen things up. The necks that I have made prior, may or may not be as stiff without the carbon fiber and I can’t say they are better or worse. I jumped on the bandwagon and never got off. I have been using them on my acoustic braces also. I feel that in the long run, the carbon fiber will not change whereas the wood is in constant motion.

As for using CF rods, I wouldn’t waste my time with it. If you put them into a rectangular slot, you’ll need to make up the difference with epoxy, and how stiff is epoxy???

Fryovanni as usual is right on the money.

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I found .092" x .220" (approx. 2.34mm x 5.59mm) solid graphite rod (in epoxy base, 21 grams / meter), in 48" lengths for around $9 each, shipped (in quantity). That's less than 1/4 of StewMac's price of $18+/24" plus shipping.

Good find! Where did you find those?

StewMac's are about twice as thick as those, so they are about the same price for the same volume (or mass) of CF.

But the thing I like about these is they are extra long, so you could use them with a neck-thru or run them into the headstock.

Peter, that's a cool finding about the CF sheet. Makes perfect sense.

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I should rephrase my post above -- I meant solid rectangular CF lengths, not "rods" which I guess implies that they have a circular cross section.

Sorry...I was referring to the "Kite rod tubes"

On a similar note narrow your search to model airplane building sites or a large Hobby center who does a lot of model airplane supplies. They use many sizes and shapes of carbon fiber when building these models, tube, rods and sheet and usually the price is half of what a guitar supplier will overcharge your for it.

Hopefully this helps

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All of the guitar necks that I have built in the past 10 to15 years have carbon fiber in them stiffen things up. The necks that I have made prior, may or may not be as stiff without the carbon fiber and I can’t say they are better or worse. I jumped on the bandwagon and never got off. I have been using them on my acoustic braces also. I feel that in the long run, the carbon fiber will not change whereas the wood is in constant motion.

As for using CF rods, I wouldn’t waste my time with it. If you put them into a rectangular slot, you’ll need to make up the difference with epoxy, and how stiff is epoxy???

Fryovanni as usual is right on the money.

I would be willing to and have used both rods, and solid rectangular stock. I wouldn't hesitate to use sheet lams either. Just to be clear :D

This is all supplimental, above and beyond what is required to make a reliable neck. So there is no wrong answer IMO(I can see why people would choose any of these material configurations, to achive what they want).

I would also note that if Myka has had good success with rods. That should be a good indicator as to the viability of using them(at least if you have faith in his knowledge and ability to judge how well a method or material works, and I do have faith).

I have used steel bar also(similar to the bar stock Warmoth sells). CF is not stiffer than steel of the same size and volume, but it is lighter. To be honest, the weight difference was not a big deal to me on that neck(neck wood makes a bigger difference in weight). If price is a real consideration for you steel bar stock will run you a couple dollars (but will be stiffer), CF tube is probably closer to 3 times that(lower stiffness possibly more unidirectional stability than similar amount of CF, but lighter per. volume of displacement), and solid of course will be 2-3 times as much as tube(lighter than steel, but a little less stiffness), sheet would be similar if not slightly more than solid bar (it would allow optimal directional stiffness per. mass. ) If weight plays a huge role in your choice look closely at your tuner weight(FWIW, there can be a very big difference in tuner weights).

Peace,Rich

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As for using CF rods, I wouldn’t waste my time with it. If you put them into a rectangular slot, you’ll need to make up the difference with epoxy, and how stiff is epoxy???

Like I said, I used 6 mm kite rod tubes -- and routed the channel using a 6mm ROUNDED bit. Doing it that way seemed so obvious I didn't think I needed to mention it.

So the tubes fit quite snugly. I also sanded the tops a bit flat to provide more surface contact with the fretboard, since my primary interest was in using the CF to minimize any chance of dead spots.

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