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Double Bass BROKEN NECK

#21
George700DL said:
I guess the only thing I'm still not convinced about is the "stronger than wood" argument for hide glue - but that is only from very limited experience, so I trust the opinion of others.
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There was a good online article about hide glue strength, but I have forgotten where I saw it. However, Frank Ford has some good info at

[Invalid or Expired Link Removed]

Look for his articles on hide glue part way down the page. Within one of these articles he points to some material by Craig Brougher:

http://www.player-care.com/hide_q-a.html
http://www.player-care.com/hideq-a2.html

I think Frank Ford's comment about "stronger than wood" is what I need to keep in mind -

"It may be that strong only for certain tests; it is not the same as the wood itself"

I don't think I will ever say that 'the glue is stronger than the wood' again. It's not a meaningful comparison and suggests a lack of understanding of the properties of wood/glue joints.

Thanks for challenging me on this, George.
 
#22
Turnaround said:
There was a good online article about hide glue strength, but I have forgotten where I saw it. However, Frank Ford has some good info at

[Invalid or Expired Link Removed]

Look for his articles on hide glue part way down the page. Within one of these articles he points to some material by Craig Brougher:

http://www.player-care.com/hide_q-a.html
http://www.player-care.com/hideq-a2.html

I think Frank Ford's comment about "stronger than wood" is what I need to keep in mind -

"It may be that strong only for certain tests; it is not the same as the wood itself"

I don't think I will ever say that 'the glue is stronger than the wood' again. It's not a meaningful comparison and suggests a lack of understanding of the properties of wood/glue joints.

Thanks for challenging me on this, George.
Click to expand...

Thanks again for the helpful info. I guess it depends on the type of joint, grain orientation, and leverage applied when trying to break it. I have ocd, but the bass build was therapeudic for me - taught me that not everything should be bullet-proof and it made me appreciate hide glue. I ev en like the smell :)

George
 
#23
Wow this thread exploded. There are some highly intellectual discussion and a few valid points throughout. Though I have to say that my experience in repairing this type of joint has led me to the conclusion that 192 gram strength hide glue just doesn't hold in this type of repair. I have done hundreds (maybe thousands) of these repairs on my rental stock. (kids are clumsy) For a while I tried to go with the purist way of thought. (Using hide glue for absolutely anything and everything in luthiery) Those joints only came back and had failed. No sort of impact was involved in many cases. In fact, one of them was just sitting in my inventory and it finally gave way too. The only thing slowing down its failure was my bamboo dowels. Since switching to 24-hour (T-88 specifically) epoxy, these joints are holding quite well.

Turnaround, most good luthiers in the world of repairing instruments (not building new instruments) will have other types of modern glues in their shops. There's times when they are appropriate and times when they are not. The Cremonese masters didn't use any other kind of glue because they had no choice. It was all that was available to them in their day. I don't think Amati and his apprentices would have turned their nose up at some of our modern glues. However they would probably have continued to recognize the versatility and appropriate use of hide glue.

If you have successfully done a neck repair like this using only hide glue and no reinforcement of any kind, I would fly to Canada to pick your brain. Obviously in my extended experience and experimentation in this type of repair, I'm missing something..
 
#24
RCWilliams said:
I would stay away from screws and or bolts, but that's jut me.
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Eric Hochberg said:
Why?
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Wood expands and contracts in varying climates, metal does not. Inevitably, the metal and wood will separate and the reinforcement that the metal initially provided will weaken severely over time. Also it's a real b%^ch to extract them when having to do the repair again down the road.

I have a few trophy screws that I have extracted from bad neck repairs. One is 5 inches long. I invested lots of choice words in that extraction.
 
#25
DallasStrings said:
Wood expands and contracts in varying climates, metal does not. Inevitably, the metal and wood will separate and the reinforcement that the metal initially provided will weaken severely over time. Also it's a real b%^ch to extract them when having to do the repair again down the road.

I have a few trophy screws that I have extracted from bad neck repairs. One is 5 inches long. I invested lots of choice words in that extraction.
Click to expand...

Thanks.
 
#26
George700DL said:
As for removing wood to accommodate the dowel - I think what Cody had in mind was thin bamboo stakes - requiring very small holes. We're talking millimeters (right?) Not a thick dowel.
George
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Yes, I use dowels typically 3-4mm in diameter. They are angled down towards the mortise as much as possible. This will help stabilize the epoxy joint and keep it from creeping. Though most of the time I'm lucky enough to get a break where the two ends mate perfectly. Oftentimes these joints will not creep if the break is rough enough that the wood fibers hold themselves together in the right place. In any case, proper clamping is also very important to eliminate creep.

Also to clarify, I also use hot hide glue on the mortise side so that the neck can still be removed from the body in the future if necessary. The epoxy is only used on the parts I don't want coming back apart.
 
#27
DallasStrings said:
Wood expands and contracts in varying climates, metal does not. Inevitably, the metal and wood will separate and the reinforcement that the metal initially provided will weaken severely over time.
Click to expand...

I'm in total agreement here but I'll take it even further - when I spline or dowel I use whatever wood the neck is made of for reinforcement. I want as similar a rate of expansion/contraction as possible so as not to fracture the epoxy repair.

Not to mention what running into hidden metal would do to your favourite saw or chisel. :(
 
#28
witnessed a major struggle this week in a failed attempt to remove a power driven 3/8 stainless steel threaded rod in a heel... couldn't drill it,shear it, or back it out. being stainless it had that nice sharp, cut thread, not the cheap rolled variety, so it was there to stay. ended up fitting a new used neck.;) it would be safe to say that i see 100+ repairs of this nature a year,different materials etc. for my part, the jury is still out on this one...the failure rate is quite high on cello and bass... a mass/tension principle going on?
.02
 
#29
DallasStrings said:
Turnaround, most good luthiers in the world of repairing instruments (not building new instruments) will have other types of modern glues in their shops. There's times when they are appropriate and times when they are not.

If you have successfully done a neck repair like this using only hide glue and no reinforcement of any kind, I would fly to Canada to pick your brain. Obviously in my extended experience and experimentation in this type of repair, I'm missing something..
Click to expand...

I use may types of glue in the repair work I do as well. I try to choose the right glue for the job. I have used hide glue for some neck repairs like the one in this thread and for things like broken guitar headstocks. None have failed so far - guess I've just been lucky.
 
#30
This is a very nice looking bass you have, I will say the same as others and take it to a properly set up repair shop, It also looks like epoxy was used at one time which is a real shame and should never be used on this type of repair, Hide glue is always the best. You will have to remove the epoxy ( if it was used ) and in doing so you will have to remove some wood, then you will need to add some wood ( maple of the approx age of the bass, if you can get some ) set the angle, glue and your going to need a support bolt or lag properly drilled thru and hide the repair as best as possible. A wooden dowel will eventually fail this type of repair and does not last long, its a chance I wouldn't take unless your restoring a museum grade instrument that will never be played. A stainless lag bolt will never fail and doesn't effect the sound at least in my experience, but I'm sure some people will disagree.
 
#32
Looking at that picture again it looks like the neck heel is built up from three pieces of wood. You see not only the big jagged crack but also one of the other joints is opening. Maybe it's time for a new neck. That scroll looks nice, maybe you want it grafted to a new neck handle. Otherwise, how about a new, German made machine carved neck?
 
#33
ctregan said:
Is there a block under the fingerboard, in the third picture down from the top?
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There is indeed.

I've cleaned out the joint with acetone and lots of picking / patience so I might post some more photos to see what people think.

As much as I'd prefer a professional to do it I don't have the time/money or know anyone good in the Brighton/Sussex area - don't suppose anyone here does? I've been to one guy but he wasn't great. So I probably will continue to work on this myself and will report every step of the way.
 
#36
Neither of these products seem to be distributed in the UK. Anyone know of an equivalent product that is?

Here are some further photos of the crack, again I pulled it open so you can see inside a bit better.

Still quite a bit of the old epoxy to get out but getting there.



crack4.jpg

crack5.jpg

crack6.jpg

crack7.jpg

crack8.jpg
 
#40
rhinceros said:
should the dowels be at this kind of angle?

also as you can see from the one to last image in the reply above, the neck appears to be in two parts, you can see a vertical line down the centre. Reckon I should just do one dowel 3 or 4mm dowel either side of this?
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That angle is about the steepest you can do on that break. I'd do at least 3 dowels small dowels. Two on either side and one in the middle.
 

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