Double Bass [kinda urgent] Yet another broken neck.

[james condino]

If you are gluing cross grain to cross grain, not trying to glue end grain that is, your glue job, if done right, SHOULD be stronger than the actual wood it is bonding. Wood magazine did a joinery test several years ago, and ALL of the common glues, and joint types, the wood, even very hard woods, failed long before the glue gave up.

Are you sure you are in the right place? That is great information if you are building bird houses and picnic tables in a static environment with no tension loading but almost useless when talking about loaded systems like instruments that have hundreds of pounds of pressure on them. The OP already proved the point- three separate times. I don't know anybody that will touch it now; who wants to deal with that mess....

Should we revisit this questionable method :

j.
www.condino.com
www.kaybassrepair.com

 

[Big Hoss]

Are you sure you are in the right place? That is great information if you are building bird houses and picnic tables in a static environment with no tension loading but almost useless when talking about loaded systems like instruments that have hundreds of pounds of pressure on them. The OP already proved the point- three separate times. I don't know anybody that will touch it now; who wants to deal with that mess....

j.
www.condino.com
www.kaybassrepair.com

Positive...

Sorry if I didn't make my point clear enough...

IF the OP got a good clean glue joint, had proper clamp pressure, and let the joint cure whatever the glue MFGs recommended time is, usually 24 to 48 hours, the glue SHOULD hold better than the wood...

Maybe I am misunderstanding the issue he is talking about, but it SOUNDS like the wood fibers themselves are giving way, so no amount of glue is going to help his situation. He didn't post up photos of the actual damage, just the repair, but I suspect the wood fibers are giving up the ghost.

Having said that, it seems to me, correctly or not, that the instrument itself if most likely beyond long term repair at this point.

 

[james condino]

Only in a static environment. Those newer glues like Titebond are subject to creep under stress load that always fails; sometimes it just takes a little longer. In simple terms, they are similar to a plastic in a solution that slowly deforms like you are stretching taffy when it is under tension (known as creep). That is why we use hot hide glue- creep is not a part of it. For furniture building and similar woodworking with no stress loads, Titebond works great. It sets in about 5 minutes and is a full working strength where- as you mentioned- the wood fails before the glue will after only about 20 minutes.

That is great- unless you have a Sawstop tablesaw. I once destroyed a $150 blade and the control module with a titebond glue up for a cabinet job. Glued and clamped everything up, got a quick bite to eat for lunch, and 30 minutes later, the glue was holding fine. What I was not aware of was that the moisture content in the boards was still so high that the Sawstop registered it like I just ran the blade through my hand and it shut down the whole system. $250+, 5 second mistake.....

That saw is long gone and was replaced with my 1953 art deco unisaw. 'Bummer because I liked the way it worked, and in a lot of ways it was a superior saw, but every single piece of junk Chinese electronics failed multiple times and the company refused to install a nice reliable Baldor motor. Not acceptable in a $4000 tablesaw!

j.

 

[Big Hoss]

Yeah, no Sawstop. Although I would like one for the safety factor. I always check stock I am cutting with a moisture meter before it meets a blade, so I am not worried about running green wood through a blade and triggering the brake.

I have never used hide glue, been wanting to try it. I know several guys that are using Titebond, particularly Titebond III for necks, not sure if they get failures because of the glue or not... Haven't followed the builds long enough.

Sorry if I digressed here, this thread combines 2 of my major hobbies, woodworking, and bass...

 

[james condino]

It was not about green wood; it was the added moisture from the glue confusing the saw. When in doubt, they shut down. Good for both your fingers and the sawblade company, because they do a number on a nice blade.

I just checked on mapquest and you are about 28 minutes from my good friend Stephen Marchione's place in Houston. Go visit him- incredible guitar builder and he'll set you straight on hot hide glue.

 

[KUNGfuSHERIFF]

"IF the OP got a good clean glue joint, had proper clamp pressure, and let the joint cure whatever the glue MFGs recommended time is, usually 24 to 48 hours, the glue SHOULD hold better than the wood...

Maybe I am misunderstanding the issue he is talking about, but it SOUNDS like the wood fibers themselves are giving way, so no amount of glue is going to help his situation. He didn't post up photos of the actual damage, just the repair, but I suspect the wood fibers are giving up the ghost."

Nope. Been there, done that with the exact same repair which had been horribly cob-jobbed by the school janitor or something. With the strings still tuned to pitch. James speaks truth. As always.

The wood fibers are not shredding. The joint is sloppy and fouled with the residue of several types of inappropriate glue. It will never join with adhesive alone.

 

[robobass]

All I can say is that I've made this repair on several student instruments and it's never failed. Pop the FB, make a clean glue-free joint, and put in one or two long screws (from the under-FB side) which will not only be a structural element, but will give excellent clamping pressure and hold the position of the joint. Hide glue (I use nothing else). You might even glue the joint lightly in order to make perfect pilot holes for the screws, then break the joint and re-glue using the screws. It has worked for me anyway.

I see no reason to remove the heel. If it's glued in with urethane or something, then you're gonna find yourself in a "world of hurt", as the wrestlers say.

 

[robobass]

...That is great- unless you have a Sawstop tablesaw. I once destroyed a $150 blade and the control module with a titebond glue up for a cabinet job...
That saw is long gone and was replaced with my 1953 art deco unisaw. 'Bummer because I liked the way it worked, and in a lot of ways it was a superior saw, but every single piece of junk Chinese electronics failed multiple times and the company refused to install a nice reliable Baldor motor. Not acceptable in a $4000 tablesaw!j.

I never heard of SawStop before. Pretty nifty idea. Can you deactivate it when you know you have moisture issues? Also, besides trashing the blade, wouldn't it throw the bearings and carriage out of whack? I'd be happy to sacrifice a blade, but I'm not so sure about a whole saw. Especially if it was glue and not skin which set off the brake.

Personally. I've been using table saws since I was twelve. So far no cuts requiring stitches, knock on wood.

 

[misterbadger]

The SawStop moisture sensor can be deactivated when necessary. I'd love to have that safety feature in my shop, but I'm wedded to a sliding table saw, and the technology isn't available on a slider. Like robobass, I'd worked on table saws since I was a kid without incident until about four years ago. My end-user-modified left thumb works fine - slightly thinner than the original, but it works great on thicker bass necks. I was lucky to escape serious injury, and would happily trade a stack of trashed blades and $70 control modules for a safer saw. A friend of mine spent $100,000 and lost six months of work recovering from a table saw accident. YMMV

 

[robobass]

Actually, they do have a sliding attachment which looks decent. Overall it seems like a lot of money for this class of saw. I just try to plan my cuts carefully, and obsessively build jigs and holders for tricky cuts. It doesn't hurt to have a CNC router in the shop to help with this!

 

[iJimaniac]

Okay, not sure why the conversation moved to saws, nor why my email updates went to spam (sorry for the late reply), but regardless thank you all for your input.

There seems to be a consensus that this predicament is due to doing it wrong the first time, and let me assure you I've considered that, but honestly I see no reason for the joint to have failed the first time. I read many posts here on the forum, concluded that PVA glue was the best bet, fit the joint together perfectly, clamped it down with several clamps and lots of pressure, then let it sit clamped for a whole week. The only thing I can figure is the wood glue I used must have been inferior, or else I just put too much stress on the joint (it gets hauled around to several outside gigs a week). For those wondering, it was the glue that failed, not the wood. I have also been careful to clean up the joint good (with a warm vinegar solution) between glues, and have sanded the last two times, so I don't think the talk of old glue residues is the problem.

For those wondering about my location, I'm close to Douglas AZ, which is in the very southeast corner of AZ. I still see people talking about taking it to a master luthier, but again, is it really worth taking a bass I paid $1500 for to a luthier who would probably charge half that much when it already has a failing top? Am I over estimating how much they'd charge? Would they even guarantee a job like this?

Regarding people still recommending screws, I've seen enough on these forums and know enough about woodworking to know that's just not going to last and will create a far worse problem when you try to correct it. I'm similarly skeptical about dowel, but not entirely sure. My band's banjo player has the thought of cutting a slot or two perpendicular with the break from the outside and inserting pieces of maple. Not sure how I'd even cut the slots though, or why I would listen to a banjo player. XD


Just so y'all know, I took the clamps off and strung it up this morning, and it has so far exceeded your (and my) expectations of popping right off under tension. We'll see how long that lasts. Being in Arizona, it's gonna be next to impossible to avoid exposing it to heat, but I think I am going to try to limit the number of outside gigs for it as much as possible. Assuming it even holds past today that is.

 

[Eric Hochberg]

You might consider purchasing Chuck Traeger's book on double bass repair. He was a long time NYC
luthier and was not opposed to using metal in certain situations.

 

[vejesse]

I think the amount of wood to wood surface area has a lot to do with how well the repair will hold up. Look at guitar peghead repairs: most of these are done with Titebond and even ugly repairs tend to hold despite having no reinforcement. Less tension with a guitar of course but I've also seen an upright bass scroll and neck heel glued back onto the neck handle with Elmers yellow glue using what amounted to 45 degree miter joints, but reinforced with multiple tight fitting splines. That one's been holding fine for many years with no sign of creep around the glue line, that reason likely being the very large amount of glueing surface area from the splines. I suspect that if the OP's repair had been reinforced with a big dowel or splines it would have held ok as well - as long as the temperature didn't get too warm like inside a hot car.

Titebond's own technical articles will tell you not to use Titebond for important structural or architectural joints (i.e wooden airplane or boat building) because of "cold creep". Like James C. I don't use aliphatic resin glue for this reason. I will use 24 hour cure epoxy for bass neck repairs. It doesn't creep, it fills small gaps of missing wood, and unlike hide glue it gives you the time to get the glue into multiple spider like cracks around the scroll or neck heel. Unless you load up the hide glue with lots of urea (defeating the purpose of using hide glue as the glue will now creep) you could never do this. You can even use a heat gun to really get the epoxy glue deep into fissures. With System 3 T88 I can even do multiple glueing sessions, cleaning off uncured glue on open wood with vinegar if you need to do a multiple stage glue up.

Right now i think your neck is toast because yellow wood glue doesn't stick to yellow wood glue. But if it breaks open again and you really want to salvage that neck with a heroic repair you could try cleaning out the glue with paint stripper that contains Methylene Chloride. Then wash it out well, glue it up with epoxy and reinforce the joint. The toxic stripper is nasty business but it will get rid of enough glue to allow the epoxy to penetrate. You won't find that in the Weisshaar book but you gotta do what you gotta do.

 

[Jake deVilliers]

You can get Methylene Chloride by itself at the plastic store - its used to bond acrylics ie Plexiglas.

 

[vejesse]

You can steam and pick a lot of the glue out as well but a bit remains in the wood pores. I really hesitate to recommend the stripper but it will dissolve almost any glue. Just don't get it on your skin: I understand the Methylene chloride draws whatever chemical that happens to be on your skin into your body. And it will literally melt your skin. In a former life I did some auto body work and we used it a lot. Get a tiny fleck on your arm and you're walking fast to the sink.

 

[ee-san]

You can get Methylene Chloride by itself at the plastic store - its used to bond acrylics ie Plexiglas.

Note: DO NOT use methylene chloride in an enclosed space! In any space, use alternative strippers if possible. If not, be sure to read this first: HAZARD ALERT - Methylene Chloride Hazards for Bathtub Refinishers

 

[robobass]

...Titebond's own technical articles will tell you not to use Titebond for important structural or architectural joints (i.e wooden airplane or boat building) because of "cold creep". Like James C. I don't use aliphatic resin glue for this reason...

+1. I don't get why anyone would use Titebond for anything at all, and white glue on anything structural. Hide glue isn't difficult to use, and the granules will stay good sitting on a shelf indefinitely. Epoxy also has its uses, although for the repairs like we're discussing here I stick with hide glue, not wanting to do anything I can't undo if something goes wrong

 

[DoubleMIDI]

Beyond some glue rest that might be more or less impossible to get off the main issue might be that he sanded the surfaces. That way the contact area gets much smaller since beyond epoxy glue does not hold well as a filler.
After seeing the break, there might not be enough wood at the neck for a screw below the fingerboard. I thing after using the wrong glue for this neck the best option would be removing all neck parts from the body, measure the total heel height, file down each part to a plan surface and add wood to get the original heel height and glue it together with hide glue. If this does not hold there is still the ugly but working option of a large long screw though fingerboard and th middle of the neck heel.