Official Luthiers Forum!

Anyone with experience of using Pultruded Carbon Rods or tubes for neck reinforcement? Here in UK, importing (Stewmac or LMI) carbon fibre bars is expensive (post, tax, duty,charges can almost double the price) but can obtain rod/tube locally.
Has anyone out there used round rod/tubes?
I am thinking so far mainly about lateral stiffness to weight ratios as compared to the rectangular sections from US suppliers, surface area left for gluing the fingerboard (round tube in round bottomed/rectangular slot)and the best glues to use.... any comments about anything else I haven't thought about welcome.
For example I can obtain 6mm od 4mm id (so 1mm wall) tubes, similar to http://www.lmii.com/CartTwo/thirdproducts.asp?CategoryName=Truss+Rods%2FNeck+Parts&NameProdHeader=Pultruded+Carbon+Rods or solid rods of almost any size for a reasonable cost.

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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.

Colin,

I use 3/8" tubes (the ones from LMI) on either side of my necks. I run them along the taper, not the center line and leave about 5/16 between the edge of the rod and the edge of the fingerboard. I make a little cap for them so they do not interrupt the gluing surface for the neck/fingerboard joint. I try to run them all the way through the headstock and as far into the tenon as possible. It has been working very well for me and does not affect how I can shape the necks, even with a slim neck everything fits. You can see in one of the pictures in this post where they are visible in the slothead openings (this guitar will get a black neck to hide them) :

http://legeytguitars.com/2010/09/01/rea ... /#more-310

It is the 4th picture in the gallery. I turned little pieces to fill the opening. I usually do that for both ends but leave the center hollow. I glue them in with medium CA lately, I used to use epoxy. I rough them up with 80 grit and rub them down with alcohol before gluing them in.

Hope that helps.

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

Colin-
I've been putting 1/8 x 1/2 CF bar in the neck of classicals and have used CF rod for 'struts' to stablilize neck blocks. Not a lot of experience, but a few comments:
- Whether you use bars or tubes be sure to bury them as deep as possible in the neck (as Burton shows). Rods/bars laid half in the FB, half in the neck (which I see fairly often online) may help FB alignment but don't do a lot structurally.
-I believe Al Carruth routs a wide groove in the neck and 'lays a bar flat' in the bottom of the recess, capping with a solid wood strip. Again, 'deep' in the neck. This is an idea I'm going to try.
-LMI's prices for CF bar are about double/triple what I find - there's a thread here on OLF about "CF supply in Canada" with some names of suppliers. Some suppliers may cut the bar into the lengths you need- which can save a lot on postage. It pays to ask about shipping details- some US suppliers are very accomodating, others not.
-Epoxy is the adhesive I'd use with CF. Again, Burton's advice about cleaning/scuffing the CF is v. important. Some CF bar/tube has mold release remaining.
-If you are using tube, adding a full-length filler (hardwood dowel glued with epoxy) adds quite a bit of stiffness, especially with thinner wall tubing.
-If you are laying a tube into a rectangular section recess, you could bed it in epoxy and CF tows, if you could get your hands on some of that. (If you know a Smallman-style builder, check there- the standard rolls have miles of tow...)

Cheers
John