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Matthew Noykos

Carbon fiber rods in the neck

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Also, there are parts all over the instrument where you have various woods in different orientations glued together. Why would a cf rod in a neck be all that different? Does it bother people because it is carbon fiber and not wood?

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I'll paste myself here:

 

Can stiffening the neck stop the relaxation of the plates; the twist and settling of the rib structure? I have only seen a couple of necks actually twist, or warp, but those soundposts become too short pretty regularly. Is the system of age-related warp really centered on the stiffness of the neck itself?

I had a small accident in the shop where I was handling a bass that was set up. It was horizontal in a cradle I'd just made for varnishing, When  the bottom slipped out and dropped 30cm to the floor. I heard an ominous pop. I quickly inspected the seams,. To my relief all was in order, but there staring me in the face was the  womperjawed fingerboard.  The bass was tuned up to full tension. I took the opportunity to measure the 2mm bow in the fingerboard joining surface and decided installing a carbon fibre rod would be necessary.   

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"Remember : because the necks break sometimes, we know we're close to yield for that material"

Not under normal use. Necks don't normally break, unless they are subjected to much higher than normal loading (such as a standing cello case falling over backwards). We're trying more to deal with deformation and creep, than breakage, not that there couldn't be a collateral benefit of reduced breakage..

 

Didn't know that - sorry.

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So, here's what I went and did:

post-24710-0-16019900-1394553827_thumb.jpg post-24710-0-41439900-1394553847_thumb.jpg post-24710-0-19641000-1394553917_thumb.jpg

 

The routed channel was then widened and cleaned by hand, the cf rod glued in, a thin strip of maple veneer then glued over that.

All of which I neglected to photograph. :rolleyes: 

I'll try to remember to take a picture of it when I remove the f.b. for varnishing.

Thoughts?

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Sure, one could fail to plan well, such as bonding  a cross-grain reinforcing member (or carbon fiber) when the wood has high moisture content, ensuring that the wood will later shrink much more than the reinforcing member.

 

Hi David - In my youth (50 - 55 years ago) I built and raced 5 dinghies/catamarans. It's in the nature of competitive sport that collisions occur, things break and repairs have to made through the wee hours of the night so that one can compete the next day.

 

A great advantage of using epoxy is its ability to be applied to and bond things under water (fresh and marine) to a damaged area and still effect a repair.

 

I wouldn't loose too much sleep over using epoxy to glue wood with a high moisture content. The epoxy effectively seals the joint line against movement of the water through the joint. The only direction for it to escape is across the grain which is a fairly safe, crack-free procedure.

 

Think sealing the end grain of a plate during the seasoning phase.

 

cheers edi

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