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Double Bass Neck Reinforcement

C

Cody Sisk

Jan 26, 2009
686
9
Lilburn, GA
Disclosures
Ronald Sachs Violins
#1
There's been much discussion in this forum regarding carbon fiber rods being installed in necks. Besides the weight, tone and stiffness considerations, how would this type of reinforcement do in a rental application? I fix at least half a dozen broken bass and cello necks a week from my rental fleet. I'm curious to know if any of you have found any carbon fiber reinforcement to help the structural integrity of a neck in the event of an accident. Will it help? or just make the repair that much more difficult?
 
#3
I am not a luthier but from the basses I have seen that have been repaired the majority of neck cracks seem to be either at the heel (short cross grain) or up at/near the pegbox (short cross grain). The carbon fiber is installed underneath the fingerboard which would not help these areas. What would help these vulnerable areas is a little redesigning to make them stronger.
 
#4
Just out of curiosity, Cody, how do you do quicky neck repairs at the heel? When I was a shop owner, we always used a tapered pin, (cello end pin reamer and tapered peg, the tapered pin always insured a good tight fit. you could probably wrap it in an aramid fiber to ad some strength, but that would probably force the use of a resin for bonding.
 
#5
RCWilliams said:
Just out of curiosity, Cody, how do you do quicky neck repairs at the heel? When I was a shop owner, we always used a tapered pin, (cello end pin reamer and tapered peg, the tapered pin always insured a good tight fit. you could probably wrap it in an aramid fiber to ad some strength, but that would probably force the use of a resin for bonding.
Click to expand...

If it is a break at the heel I will leave the neck mortise intact, take the fingerboard off then glue the neck back on with wood glue and reinforce with two or three 1/4" bamboo dowels. Of course this is dependant on the roughness of the break. Most of the time, the wood fibers will eliminate any creep with the wood glue. I don't like going through the fingerboard with a tapered peg; it's an aesthetics thing more than anything else..

(Ok so you hide glue purists out there might scoff but here's my reasoning. I've experimented with epoxy, hide glue, white glue, superglue and yellow glue to repair these rental workhorses. The best solution I've found for these instruments that are dropped over and over again is yellow wood glue. Every other method fails eventually. No they aren't to one day become pedigree instruments so keep your pantyhose on. :ninja:)
 
#10
It might be worth researching how and when the instruments break. During playing? Sitting around the house? Transportation? I'm just wondering if hard cases would help.

Although... I've got two kids in string lessons, and I do see a lot of kids who just have to wriggle all the time. Eventually their bows or instruments go flying.
 
#12
Those cheap chinese instruments that you are renting are made with really soft wood. I've fixed a number of broken bass necks on our rentals as well. I tend to think reinforcements might help the neck stand up to the tension of the strings, but not so much to impact damage. Even if your bolt or carbon fiber rod holds, the wood can still crack. Repairing the damage will basically be impossible too. I tend to think that you just need to find the cheapest and easiest way to repair these sorts of breaks and live with it. I can tell you that for cheap cellos and basses with broken heels, we do the repair with the fingerboard on and plug the fingerboard with used cello pegs. It makes things much easier, and its functionally and visually fine. I tend to think this is a better solution than removing a fingerboard that's been glued really strongly like they usually are and risk damaging the neck. Of course, you would never do any of these repairs to a nicer bass, but if you need to get more life out of an instrument that isn't worth replacing the neck on, do whatever it takes.
 
#14
JoeyNaeger said:
Those cheap chinese instruments that you are renting are made with really soft wood. I've fixed a number of broken bass necks on our rentals as well. I tend to think reinforcements might help the neck stand up to the tension of the strings, but not so much to impact damage. Even if your bolt or carbon fiber rod holds, the wood can still crack. Repairing the damage will basically be impossible too. I tend to think that you just need to find the cheapest and easiest way to repair these sorts of breaks and live with it. I can tell you that for cheap cellos and basses with broken heels, we do the repair with the fingerboard on and plug the fingerboard with used cello pegs. It makes things much easier, and its functionally and visually fine. I tend to think this is a better solution than removing a fingerboard that's been glued really strongly like they usually are and risk damaging the neck. Of course, you would never do any of these repairs to a nicer bass, but if you need to get more life out of an instrument that isn't worth replacing the neck on, do whatever it takes.
Click to expand...

This thread might be of interest to you Joey. This method really makes taking the fingerboard off of these a piece of cake when it would split the neck and/or fingerboard otherwise.
 
#16
fdeck said:
It might be worth researching how and when the instruments break. During playing? Sitting around the house? Transportation? I'm just wondering if hard cases would help.

Although... I've got two kids in string lessons, and I do see a lot of kids who just have to wriggle all the time. Eventually their bows or instruments go flying.
Click to expand...

Every broken DB neck I've seen is from the instrument falling: falling after being leaned against the wall, falling out of stands, falling when the player spaced out and reached for something else... :(

Basses have a lot of mass at their highest point (the tuners) and once it gets going its hard to stop. The neck is usually (but not always) strengthened sufficiently by the fingerboard, so that leaves the short grain at the heel as the victim.

The damage does move around depending on what part hits something solid first and sometimes the neck just pops out of the mortise but mostly its blind maple dowels and epoxy in the heel for me.
 
#17
DallasStrings said:
This thread might be of interest to you Joey. This method really makes taking the fingerboard off of these a piece of cake when it would split the neck and/or fingerboard otherwise.
Click to expand...

Interesting. I've tried using an iron and a heat gun to do the same thing, but with no real success. I guess it makes sense that the heat blanket would heat the whole fingerboard more evenly. More tools to talk my boss into buying...
 
#20
Jake deVilliers said:
Every broken DB neck I've seen is from the instrument falling: falling after being leaned against the wall, falling out of stands, falling when the player spaced out and reached for something else... :(

Basses have a lot of mass at their highest point (the tuners) and once it gets going its hard to stop. The neck is usually (but not always) strengthened sufficiently by the fingerboard, so that leaves the short grain at the heel as the victim.

The damage does move around depending on what part hits something solid first and sometimes the neck just pops out of the mortise but mostly its blind maple dowels and epoxy in the heel for me.
Click to expand...

Well, having watched kids at group lessons, recitals, etc., nothing surprises me any more. :eek: My son's 1/4 size cello had a repaired neck heel when we got it.
 

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