Official Luthiers Forum!

I use two .125" x.375" CF rods,each spaced about .125" from either side of the two way truss rod. They are glued with epoxy. This is a bit messy and I was thinking of going to CA. Wonder if any one does this and if they have experienced any problems.
Tom

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A person who has never made a mistake has never made anything!!!

I might work if you use thicker CA glue. My truss carbon rods are thickness that they come from the mfgr and my slot is the width of my bit. They don't quite match. I wear nitril gloves and use epoxy and live with the mess.

I've used medium CA with no problems. It can leach through the pores so I seal the slots with shellac before gluing. Masking off the surface of the neck except for the slots for CA or Epoxy helps with the mess.

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

Remember to that if you choose to use epoxy it likes a small gap of about .002.
Tape along the deges helps BTW.

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Jim Watts
http://jameswattsguitars.com

To control the epoxy mess, I lay a wide piece of masking tape along the neck surface, then carefully cut away the tape (with a sharp exacto knife) over the slots. Pull the tape before the epoxy fully sets & it's no muss no fuss.
Thin CA would almost for sure wick through the pores & show up as dark spots on the back of the neck. Medium CA might work, but I don't see it being any less messy.

I put the two CF rods and the truss rod all in one wide slot, well-fitted, so only one side of the CF rod gets epoxied. Not as much epoxy mess that way, but some.



Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Just speculating here, but with the MOE of CA being what it is, I would not want to use it in an area where movement is expected, and adjustments from initial setup point of the glue will be made during set up of the guitar. I am sure it would be fine in the short to medium term, but given this glues capacity to sheer like glass if it does fail, I would not be confident about its longevity. If you want evidence of the sheer to which I refer, try routing off the bindings of a guitar that where fixed with CA and you will see what I mean as they shatter off well ahead of the cutter. Epoxy on the other hand has 'the' perfect MOE for the job at hand....but as always when working with epoxy make sure the area is well ventilated and preferable have a fan running to push the fumes away from you.

Cheers

Kim

One way to avoid the mess is to glue on the fingerboard at the same time as you install the CF bars (I do).

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Rian Gitar og Mandolin

Has anyone tried any of the non-toxic glues, like yellow/white/hide? I ran a quick test a while back, gluing a CF rod to a scrap with a dot of LMI white glue, and it peeled off quite easily, like the glue doesn't bond well to the CF. But when it's packed into a slot, maybe it wouldn't be a problem. I'll probably just suck it up and use epoxy, but it would be nice to avoid it.

On a slightly different note... do most of you guys cut an angle in the CF rods so they can extend as far as possible into the headstock? If so, what do you use to cut the CF? Dremel cutting wheel, perhaps? I've been thinking about simply cutting the slots 1/16-1/8" deeper and adding a wood strip over the CF. That way I can get the CF just past the nut area, and plane the headstock and fingerboard gluing surfaces like normal, plus don't have to worry about getting the slot depth precisely equal to the CF height. I use a pretty hefty handstop to strengthen the nut area anyway. But burying them deeper does bring up concerns of where the CF is in relation to the neutral axis (to get maximum benefit), and cutting through to the CF when shaping the neck, if it's very deep on a thin neck.

I always glue mine in with fish glue, works perfectly and cleans up easily. I don't use any CA or epoxy in my instruments, ever.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I'm not quite as averse to CA and epoxy as Colin, but I too use fish glue for the CF bars (and fingerboard).

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Rian Gitar og Mandolin

Yes, fingerboard for me as well.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Yes, and when I cut CF rods or tubes I use a hacksaw with a metal blade (and wear a dust mask…). BTW pretty much every glue will work there as the rods have nowhere to go.
I fail to see how CA will shatter, unless the neck is broken and then it is too late… Besides, medium CA tends to be softer than thin CA when cured.
I use CF rods dadoed into fretboard and neck stock for tilt-necks and use polyurethane glue to glue CF rods and fretboard, the squeeze out cleans out easily with a chisel. I've used aluminium rods for this successfully too. And I use polyurethane glue to laminate necks too. It pains my stomach, but I do.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Colin,
can I ask, do you source your fish glue in UK?
If so, do you mind telling me where?
(Closest source I've found so far is Martin Guhl, in Germany)

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I only have used CF bars on some of the Bass's I've built. So far no problems and I never used any glue at all. Is that bad? Why glue in the bars when they fit in nice and snug?

Colin, I do get mine from Germany, but from Kremer Pigmente, here's the link:

http://kremer-pigmente.de/shopint/index.php?cat=0201&lang=ENG&product=63550

One 250ml bottle will do quite a few guitars, shelf life is good so I usually get a couple of 250ml bottles at a time. I believe that Madinter has the Lee Valley glue.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Kremer. Madinter is out of stock for more than 1/2 year.

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Build log

I have no idea of the bond strength of fish glue to CF, but you do not want to thinks of the glue as a filler.
Properly bonded in place, the CF and neck wood will act as a composite and give much greater stiffness than if it were just sitting in the slot.
But to do that, the adhesive needs to be able to transmit shear forces between the CF and the surrounding wood.

It's poor.
I also had gotten curious about other glues than epoxy for CF and gave it a try yesterday. I glued pieces of wood with Titebond original, fish glue and epoxy to a sanded CF rod. This morning I accidentally dropped the rod to the floor and the two pieces glued with TB and fish glue just splintered off.

Thanks everyone for the input. Markus you sealed it for me as to what glue to use.
Tom

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A person who has never made a mistake has never made anything!!!