I've only ever used CF tubes. The pultruded ones from LMII, specifically. The couple of times I've need to cut them, I used a hack saw. Takes maybe 10 seconds.
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Reasonably Priced Source for Carbon Fiber Rods?
- Thread starter Gilmourisgod
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I've only ever used CF tubes. The pultruded ones from LMII, specifically. The couple of times I've need to cut them, I used a hack saw. Takes maybe 10 seconds.
The rectangular rods seemed simpler only because it’s just a square channel cut, but I suppose tubes could fit in a square cut slot as well. This all begs the fundamental question of how necessary/effective they are in a 4 string bass. I put them in the Hossenfeffer 1 bass, and so far the neck seems really stable, so..... it did no harm, anyway. I have a Warmouth neck with rods that’s also very stable, which gave me the notion to do it on my builds. Seems fairly common on TB, but not universal.
And as usual i forgot the main reason i posted. The woven tubes were somewhat less expensive than the pulltruded stuff, but that was back when there was far more demand for CF in all it’s forms, than supply.
I think the effectiveness has more to do with the neck material and construction than how masny strings. On a laminated hard maple neck, I dont think it's worth the bother. But on a single piece mahogany neck, or walnut, its more useful.
Two pultruded rods from LMII cost like $11. Less than the cost of a single woven rod.
Two pultruded rods from LMII cost like $11. Less than the cost of a single woven rod.
No experience cutting CF but a thought / question. If the tool is suitable would it help to have some water trickling or running over the cut to help keep the dust down and clear out the sharp slivers?
Wow, @T_Bone_TL that's a very great offering.. it's one of those moments when I feel that the people around here are really special, generous, kind... it's the best forum I've ever been part of.
I found some 12K TOW online in the UK on ebay, 25 meters + shipping to Poland was around 14$ - thats way cheaper that any carbon rods I could find online. I will try @Bruce Johnson's method, thanks for sharing Bruce!
I'll recommend everyone in europe to check the ebay sources BTW. how wide do you rout the channels for that kind of installation?
From what Bruce has written (and what I see looking at my huge bobbin of TOW) you don't need a lot of space (and you'll need half what I do with 12K since the fiber, bundled up tight like a rope, is perhaps 3/32" or ~2.4mm per Bruce) - but being fiber, not a rod or plate, it will conform to the slot you put it in, so you can make it wide and shallow or narrow and deep as suits. I have not done anything with mine yet, but I think I gather from some of the other users (model airplane folks) that you could also flake it out thin/flat/wide and laminate it right into a glue joint - or Bruce has mentioned making a small slot in a lamination to tuck it in the back where it does the most good (if you laminate it in as you glue up) without needing to cut a deep slot from the front. That does require planning so you don't cut into it when carving the neck.
The ebay prices seem similar for the small quantities. Which is what made me throw up my hands and go big - My supposed 2500m was $85, and even though it was not actually a full roll as described, there's probably at least 2200m on there - presumably a lifetime supply unless I go nuts or build a kayak from it.
- sometimes I just get caught up in the chase and lose a detail here or there.An amusing part is that if they had described it accurately as a partly used roll I might well have been happy to pay the same and would not consider them a sleazy vendor. But it was close enough that I didn't feel like going through rejecting the deal and sending it back for a do-over. I assume that's where the expensive short pieces come from sometimes...
Or is that 200x (176 adjusted) since mine is 24K and I was just counting length above? Anyway, you get the idea, and at least for the way I'm wired, that sort of math pushes me over the edge even if I doubt I'll use 100m in the next 2 years. Of course repackaging labor and shipping would drive costs up some, but the disparity seems extreme.
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Cut them with a Dremel. You can get 20 pacs of Fiberglass reinforced cutoff wheels at Home Depot. They won't explode on you while cutting. Carbon fiber rods also sand very well, so get it close with the cutoff wheel and sand the last bit.
I've never had a problem cutting carbon fiber bars, tubes, or sheets with normal steel saw blades. I usually use one of the mini-hacksaws or a full size hacksaw. A bandsaw works too, although you may not want to contaminate your woodworking saw with fine black powder.
I cut the TOW with scissors.
I cut the TOW with scissors.
For cutting I'll use my kevlar shears, but that's because I have kevlar shears (fiber optic project) and might as well use them some more. Basically just a nice pair of shears with serrations to keep the fibers from sliding away from the cut point. Not really a problem with carbon, but it is with kevlar.
It's quite possible that I'm going to end up with two carbon-fiber reenforced wheelbarrows as that seems like a good trial/test application for placing it, and I have the stuff coming out of my ears now (wait, no, that's just hairy tufts like @Fat Freddy ...)
It's quite possible that I'm going to end up with two carbon-fiber reenforced wheelbarrows as that seems like a good trial/test application for placing it, and I have the stuff coming out of my ears now (wait, no, that's just hairy tufts like @Fat Freddy ...)
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Tom (b3e) asked about using my method of reinforcing necks with carbon fiber TOW; how deep and wide should the slots be for embedding the TOW down in the neck.
Think of the carbon fiber TOW as being a cable that you are stretching along the back of the neck to reinforce it. Like you had put a length of steel cable and a turnbuckle right on the back of the neck, screwed down at both ends and tightened up taut. That's what you are doing. When the neck tries to bend forward, the tight cable resists and holds it back.
So, the little bundle of TOW should be buried down deep in the neck, close to the final back surface. Ideally, within 1/8" of the back surface, if you dare. That requires some engineering and measuring to make sure that you know where that final back surface is going to be, in relation to the top surface of the neck blank.
The bundle of TOW is actually quite small in diameter. I normally use two strands of 12K TOW or 4 strands of 6K TOW. Either combination is less than 1/8" diameter. You could theoretically cut a 1/8" wide slot, tapering from around 1/2" deep to 3/4" deep. Stuff the TOW and epoxy down in the bottom of the slot, with an 1/8" thick piece of maple filling the slot above it, up to the surface. But it's tricky to cut a slot that narrow and deep.
It's more practical to rout a 1/4" wide slot to that depth. And it's easier to get the epoxy and TOW positioned down in there. Fill the slot with a 1/4" thick strip of maple.
The slot and filler strip can be whatever width you want, for you to be able to cut it. As long as that little bundle of TOW, saturated with epoxy, is down deep in the neck. That's where it will be most effective.
If you are using a single truss rod, and want add this TOW reinforcement, rout a slot that's wide enough for the truss rod (1/4" or whatever), but rout it down to the full depth, within 1/8" of the final back surface. Lay in the epoxy and TOW down in the bottom and clamp in a maple filler strip above it. After that's cured, trim off the filler strip flush with the surface, then re-rout the slot for the truss rod, to whatever depth it needs to be. That puts the carbon fiber centered on the neck, down below the truss rod. That's much more effective structurally than a pair of bars on either side of the truss rod. And much less weight. The carbon fiber TOW installation adds hardly any weight to the neck.
Think of the carbon fiber TOW as being a cable that you are stretching along the back of the neck to reinforce it. Like you had put a length of steel cable and a turnbuckle right on the back of the neck, screwed down at both ends and tightened up taut. That's what you are doing. When the neck tries to bend forward, the tight cable resists and holds it back.
So, the little bundle of TOW should be buried down deep in the neck, close to the final back surface. Ideally, within 1/8" of the back surface, if you dare. That requires some engineering and measuring to make sure that you know where that final back surface is going to be, in relation to the top surface of the neck blank.
The bundle of TOW is actually quite small in diameter. I normally use two strands of 12K TOW or 4 strands of 6K TOW. Either combination is less than 1/8" diameter. You could theoretically cut a 1/8" wide slot, tapering from around 1/2" deep to 3/4" deep. Stuff the TOW and epoxy down in the bottom of the slot, with an 1/8" thick piece of maple filling the slot above it, up to the surface. But it's tricky to cut a slot that narrow and deep.
It's more practical to rout a 1/4" wide slot to that depth. And it's easier to get the epoxy and TOW positioned down in there. Fill the slot with a 1/4" thick strip of maple.
The slot and filler strip can be whatever width you want, for you to be able to cut it. As long as that little bundle of TOW, saturated with epoxy, is down deep in the neck. That's where it will be most effective.
If you are using a single truss rod, and want add this TOW reinforcement, rout a slot that's wide enough for the truss rod (1/4" or whatever), but rout it down to the full depth, within 1/8" of the final back surface. Lay in the epoxy and TOW down in the bottom and clamp in a maple filler strip above it. After that's cured, trim off the filler strip flush with the surface, then re-rout the slot for the truss rod, to whatever depth it needs to be. That puts the carbon fiber centered on the neck, down below the truss rod. That's much more effective structurally than a pair of bars on either side of the truss rod. And much less weight. The carbon fiber TOW installation adds hardly any weight to the neck.
That's very informative, thank you very much for sharing. I didn't thought of placing the TOW under the trusrod, but it makes a lot of sense when I think about it. I guess the most delicate part is not to cut into the reinforcement while shaping the neck. Definitely some good measuring is needed here.
I think the essence there is plan, measure, and stick to the plan. Deciding to artistically alter without reference to the plan might cause swearing. Make any changes in the paper stage rather then the carving stage, or at least while holding a measuring device and a record of exactly how deep the slot was at THIS point on the neck for any place you think you might change...
Or, go hog-wild free form and then embrace the skunk stripe (which might involve some tricky routing if you're carving first, cutting the slot second.)
Given the extent to which CF and Fake CF are used as decorative motifs, I'm also wondering if a "right on the surface (or inlaid, if you will), loud and proud" approach might work for some. Not classic and timeless, to be sure.
Or, go hog-wild free form and then embrace the skunk stripe (which might involve some tricky routing if you're carving first, cutting the slot second.)
Given the extent to which CF and Fake CF are used as decorative motifs, I'm also wondering if a "right on the surface (or inlaid, if you will), loud and proud" approach might work for some. Not classic and timeless, to be sure.
Bee tee dubs, this is the router bit I use to route a channel for LMII's pultruded carbon fiber tubes:
Roundnose Bit, 1/4" Shank, 1/4" Cutter Dia. | Grizzly Industrial
It's the same bit i use for routing round-bottomed slots for BBG truss rods and StewMac's low-profile truss rods. Fyi, I use loctite 5 minute epoxy to hold the CF tubes in the slots, and fill in the gaps.
For those truss rods, I switch to a 3/8" round nose bit for the end-bit where the adjustment assembly is. This one:
Roundnose Bit, 1/4" Shank, 3/8" Cutter Dia. | Grizzly Industrial
Roundnose Bit, 1/4" Shank, 1/4" Cutter Dia. | Grizzly Industrial
It's the same bit i use for routing round-bottomed slots for BBG truss rods and StewMac's low-profile truss rods. Fyi, I use loctite 5 minute epoxy to hold the CF tubes in the slots, and fill in the gaps.
For those truss rods, I switch to a 3/8" round nose bit for the end-bit where the adjustment assembly is. This one:
Roundnose Bit, 1/4" Shank, 3/8" Cutter Dia. | Grizzly Industrial
Yes, you could certainly do that. If you have an existing neck which is just too springy, you can stiffen it up by adding a carbon fiber TOW skunk stripe down the back. Rout a shallow channel down the center of the back. Obviously, if it's a single-acting single-rod (ie Fender) truss rod, be really careful around the 5th fret not to hit the steel with the router.
Then, you can lay in a couple strands of TOW in a bed of epoxy colored black. Or fit a nice strip of contrasting wood on top of the TOW, to make a neat skunk stripe.
Yes, you can make your own rectangular (or whatever) carbon fiber bars, if you want to. The commercial bars are usually made by a process called pultrusion, with a polyester resin. A long bundle of TOW strands are held at both ends and pulled tight. Then they are pulled through a heated die, as polyester resin is fed in. Going through the die, the resin gets compressed around and through the TOW, and is cured by the heat. Out comes a black rectangular bar. It's not solid carbon fiber. Some percentage (maybe 20%?) of the volume of the bar is polyester resin. Like the resin in fiberglass.
But you don't need to do all that. You can make your own by gravity casting the bar in a mold with epoxy. I made up some interesting cartridge-type truss rod assemblies two years ago. Basically a truss rod cast into the middle of a bar of carbon fiber, aluminum plates, and epoxy. I made up a long rectangular mold from aluminum bar stock bolted together. All the components went inside, and was poured full of West Systems epoxy. Open top, no vacuum chamber. It worked very well.
The same technique could be used to make custom carbon fiber/epoxy bars of whatever shape you wanted.
But you don't need to do all that. You can make your own by gravity casting the bar in a mold with epoxy. I made up some interesting cartridge-type truss rod assemblies two years ago. Basically a truss rod cast into the middle of a bar of carbon fiber, aluminum plates, and epoxy. I made up a long rectangular mold from aluminum bar stock bolted together. All the components went inside, and was poured full of West Systems epoxy. Open top, no vacuum chamber. It worked very well.
The same technique could be used to make custom carbon fiber/epoxy bars of whatever shape you wanted.
Means2nEnd
Supporting Member
Hey Bruce I'll take 50 of those asap...
Sorry, that project is on the shelf for now. I did the R & D and made up most of the tooling. Two of my regular Luthier clients tested prototypes, and they worked beautifully. I got a lot of interest from other Luthiers; definitely a viable product. But I've put it all on the shelf for now (literally), for various reasons. Mostly because I don't want to be spending a greater chunk of my time manufacturing truss rods. I want to spend more of my time developing and building my Scroll Basses.
Bit of geeky information here as I have a chart in front of me of young’s moduli (E) for different material which is the relation of how much a material will strain (deform) to stress (applied load) in a linear fashion and then return to its original shape (linear elastic).
The bigger the E the less it will deform.
Epoxy only: 2 GPa
Aluminum: 70 GPa
Steel: 200 GPa
Carbon fibers only: 400 GPa
This tells me a few interesting things:
If you make your own carbon fibre/epoxy matrix you’d better pull it tight! The epoxy is basically useless (compared to the fibers that is, not wood) and the fibers have to take up any slack before they undergo any strain (and this take any load).
Steel will be much stiffer than aluminum, so why bother with aluminum? It’s not like rust is a concern encased in the neck. Aluminum is likely stiff enough though and you don’t have to think about rust if your epoxy has any porosity/air gaps.
I need to stiffen the neck of a double bass and am thinking of just using a flat bar or two- basically to cut slots in the neck and epoxy them in place. The critical factor will be the bond between the epoxy and the steel, and of course not messing up the neck cutting the slots.
The bigger the E the less it will deform.
Epoxy only: 2 GPa
Aluminum: 70 GPa
Steel: 200 GPa
Carbon fibers only: 400 GPa
This tells me a few interesting things:
If you make your own carbon fibre/epoxy matrix you’d better pull it tight! The epoxy is basically useless (compared to the fibers that is, not wood) and the fibers have to take up any slack before they undergo any strain (and this take any load).
Steel will be much stiffer than aluminum, so why bother with aluminum? It’s not like rust is a concern encased in the neck. Aluminum is likely stiff enough though and you don’t have to think about rust if your epoxy has any porosity/air gaps.
I need to stiffen the neck of a double bass and am thinking of just using a flat bar or two- basically to cut slots in the neck and epoxy them in place. The critical factor will be the bond between the epoxy and the steel, and of course not messing up the neck cutting the slots.
