Explosive...

Wow... has any of you pro guys had this happen? One one of my mini ukes I had sitting up under string tension had a bridge explosion in the middle of the night last night. These little minis have more tension that I had thought for sure. Kinda makes sense tho with such short strings I reckon. But, for some reason, one of the rosewood bridges exploded and simply came apart on me. Anyone have that happen? Other than the obvious (tension) what might cause that? An un-noticed crack, or grain flaw? Or what? I haven't had any do that yet (altho I don't have that many builds under my belt yet). But, this was pretty cool, but being one that likes to use failures and mistakes as learning tools, I would like to know how and why of things. Wonder what happened there. I use titebond II to glue the bridges down. But I also use a bridge pad under the top, as well as two dowel posts to also support it under tension. It snapped the dowels too. It didn't pull the dowels out, it snapped them . The glue didn't give way, there is still part of the bridge still securely glued down. The back half where the slots and holes for the string knot just blew up. I can't find where that piece of bridge went either. Kinda cool, but at the same time, I sure would like to figure out what I did wrong, so I don't do that again.. lol

Tudorp said:

........These little minis have more tension that I had thought for sure. Kinda makes sense tho with such short strings I reckon......

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Shorter scales have less tension on the strings,....not more. Very curious the dowels snapped also, although not sure you need them. Some use a few small dowels as a locating device to get the bridge glued up accurately, but they are small and not there for structural reasons.

I'm wondering if you might have inadvertantly tuned it an octive higher than the norm. With such a short scale any usual stings (soprano scale say) strings would feel a bit sloppy. If they didn't flop a bit,.....you might have gone way up in tension at the next octive. The tension would then be very high for sure.

......maybe?

It's the only thing that makes sense since the dowels snapped and the bridge came apart in a few pieces, one of which disappeared. You might have to go with fatter strings tuned in the right octive range to get a reasonable overall tension, (tenor strings maybe?), but you're on new ground working such a tiny scale.

You could probably not have chosen a more inappropriate glue to use for lutherie even though you say it did not fail. It would have eventually because of cold creep; that stuff is like cold rubber and tonally is probably the worst glue to use in a uke or guitar other than rubber cement.

I don't understand the dowel thing; are you doweling the bridge to the top? If so, that too is inappropriate and should not be necessary at all.

Grain direction? Rift is often best for bridges...not flat nor quartersawn.

Point well taken about pitch. An octave above standard uke pitch? With a scale length of what? You could only safely go an octave above if your scale length is half of standard.


I read your posts and see a person who seems to steadfastly refuse to read up on or research what's been working for decades in lutherie. You seem to want to reinvent the wheel, and that tendency comes back to bite you in the ass time after time. I'm known in the field for innovation, but I first trained in very traditional lutherie, and I have read and absorbed voraciously all the books, magazines, and articles that I could. Any innovative work I have done is based on understanding the strengths and weaknesses of traditional luthierie. Repairing guitars, basses, and ukes for 47 years has also helped me understand what goes wrong...and what stays right over the years.

I would highly advise that you go back and do a lot of homework before frustrating yourself any more. There's nothing you're doing that hasn't been done successfully before, and the information is literally right at your fingertips. Also, join the GAL and ASIA, get all the back issues of the publications you can afford, read way beyond just ukulele building, learn the properties of all the materials you're working with including adhesives. Slow down; get grounded; do a lot of homework; then you'll be ready to build successful instruments.

Rick, what glue is used for this? I had thought that titebond was the glue of choice for building ukes? I had other wood glues, but started using titebond because it was recommended. I understand that doesn't mean it's the right one to use, but maybe I got the wrong advice on that? If that the case, what is the glue to use for general build?

And Rick, by GAL are you refering to this website? http://www.luth.org/

I believe if limited to one glue the "Original" Titebond would be the best overall choice. Hot hide glue is great for most things too, but the very limited set up time a detriment to bridge glue on. The 5 minute or so window of the original titebond a big help in getting the bridge positioned correctly and allows for some cleanup time at the edges with a stightly moist paper towl.

The original titebond is also recommended by stewmac as a main glue to have for instrument work.

http://www.stewmac.com/shop/Glues,_adhesives/Wood_glue/Franklin_Titebond_Glue.html?tab=Video#details

check out the short video there....

Ahh.. i see what Rick was talking about. I put 'II" in my original post. I have no idea why I added that. I used the original titebond. I heard and read before that titebond II and III to stay away from. My bad..

Rick, do you agree with the original Titebond?

The glue did not fail, the wood did. Choose a better piece of wood and reglue. You can use Titebond or Hot hide glue or whatever you want. Don't over think this. You seem to be having fun experimenting with ukes and since you do sound like you are going into uke production any time soon or have to worry about warranty work, use Titebond original and just keep building. If something fails, fix it.

joejeweler said:

Shorter scales have less tension on the strings,....not more.

Click to expand...

Given that they are tuned to the same pitch, and Tudorp's uke wasn't in the vid he posted.

*sound of opening a can of worms*

I've banished Titebond from my shop; I don't care how many thousands of instruments are assembled with it; it's not the best choice these days. For a modern easy glue, we use LMI white glue; it dries closer to the hardness of hot hide glue and doesn't exhibit the cold creep that even original Titebond does. The cost is no big deal, and I like knowing that it's less likely that joints will move and fail over the years using it.

But for most of the critical body joints in acoustic instruments I've come back to hot hide glue. The issues of working with it quickly are greatly overstated, and if it's going to take you more than the liquid time of the stuff to glue a bridge on a uke, you probably need to get your act together better. We do ALL of the body glue joints on our Buddy Holly J-45 replicas with hot hide glue, and that's a lot more surface area than anything you deal with on a uke, and the timing is just no big deal. We do heat parts with a heat gun, and we're ready to go with no fumbling for clamps when we glue. I especially love it for top and back center seams because any excess glue just powders away when we thickness sand. HHG is very sanding friendly. Every guitar, uke, violin, etc. before about 1960 or so was assembled with HHG, and so was King Tut's furniture! A lot of the failures of old HHG are attributable to the fact that factories used to not particularly care about mixing the glue carefully and using fresh glue. It was common to just add more glue to the pot, pour in a bit of water to control the viscosity and just keep going day after day. They'd shut to glue pot off at night and let a crust form on the top, and then just fire it back up the next day. Funky...

Read up on Frank Ford's site www.frets.com and don't be afraid of one of the best glues on the planet.

Another issue? You get bragging rights using HHG, and some companies like Martin get huge up-charges for custom guitars made with HHG. Tim Teel, one of the stalwarts in the R&D department at Martin told me that he thinks that the single biggest contributing factor to how good their "Authentic" series of guitars sound is the use of HHG. They are absolutely fantastic instruments...one of the best D-18s of any age that I've ever played was a brand new one of that series. All HHG construction. Tim has had enough Martins under his fingertips to know what makes a difference and what doesn't. I trust his judgment as much as anyone I know in the guitar biz.

Just because lots of people have used Titebond does not make it the best choice. You can move forward or backward to a better glue...forward to LMI, backward to HHG.

And don't think I don't like modern adhesives. I use WEST epoxy for most joints in neck construction because it doesn't involve adding water to the glue line, hence the glued up parts are more dimensionally stable. I can take a fingerboard off if I need to...no problem. And I love CA glue for a number of things including gluing frets in. But for acoustic body construction, HHG is the stuff....And it just isn't that big a deal to use...

For those worried about the open time of Hide there is a very good alternative in liquid fish glue. Used straight from the bottle. It has different properties in that it has a long open time and a long clamp time. That can be both an advantage and a disadvantage, dependent on the situation. It is at least as strong as most Hide glues.
The only other glue that I use is hot Hide, which probably accounts for 80% of my glued joints. Way back in the early '80's I used PVA and Titebond Original - sometime later. The vast majority of Guitar makers mistrusted Hide glue, stating that it was both weak and prone to failure. You would be an absolute fool to use the stuff on a centre seam or a Bridge.
Fast forward 10 years and I met a Fiddle maker who exclusively used Hide (as virtually all fiddle makers do). I informed him that Hide simply wasn't up to the job for the tension exerted on the joints of a Guitar. (I'd never actually used the stuff!!) His face conveyed utter disbelief. He promptly told me to go visit a few Museums holding collections of musical instruments. Centre seams on Guitars and Violins that were over 350 years old, still very much intact. Lute bridges that held 25 strings at a combined tension of over 75 Kg - yet that very bridge has a footprint half that of a modern Guitar. 19 th century Romantic Guitars where the Neck is a butt joint onto the body, no screws/nails.
That's all the evidence one needs.

Hide glue, dovetail joints, scalloped bracing, cellulose lacquer, French Polish - they all command an unexplainable up-charge... The great repaireman and true expert Frank Ford is largely responsible for advocating the greater use of these - everyone should bookmark his great site frets.com if they are at all serious about building.

If you have a busy production shop HHG is a sensible choice. However, the covenience and efficiency of cold glues cannot be ignored and despite the obvious virtues of HHG Titebond original will remain my glue of choice...

As Rick does. HHG for the entire body. Ukes, Guitars, Weissenborns even. A Mate uses it for his Double Bass's. It's dead easy. WEST Systems for fret board. CA for inlays. The students even use HHG without issues.

As far as a bridge flying off but leaving wood behind, it seems that there is a problem with the bridge itself, or perhaps the design. I've seen some that have broken off the tie block area because the trough between it and the bridge was too deep. And sometimes you just have a dodgy bit of wood.

And dowels do bugger all except to perhaps help in locating....but there are much better options there.

Has anyone tried Titebond's hide glue? I'm trying it out on a soprano build and I really like it. So much easier to clean off than regular titebond, and I can sound all classy and posh saying I use hide glue.

Used it once, many years ago. It has an awful reputation amongst Luthiers.

Lot's tried I'm sure. Many failures that I've heard of. Nuf said.

If you want to make your own fresh liquid hid glue (glue that doesn't gel at room temp) then you add either salt or urea to the mix. Heat it up and when it cools it stays liquid.

You can literally just piss in it. Not that I'd want to, but what's the big deal about hot hide glue that makes people avoid it?

There is a hide glue that is liquid at room temperature that does have a good rep..."Old Brown Glue", but I just don't see any reasons not to use HHG.

What glue should I use to repair a broken neck? It's a clean break and seems to fits together well.

Here is a picture.

The Fine Woodworking magazine did on article testing 6 different glues back in their August 2007 issue. I will have to give you a short version of what was in the article due to its length, and perhaps you can read the full thing in their archives online if it is still available. You may find it interesting as I did.

Three woods were used in the test: White Oak because it has an open grain, Maple because it has a tight closed grain and Ipé because it is difficult to glue due to its density and resins. A bridle joint, also known as open mortise and tenon, was used because it has no mechanical strength and relies entirely on the glue bond. Three kinds of joints were made for each kind of wood: loose, snug and tight.

Six glues were used: 1-Elmer's PVA Carpenters yellow glue (which is like Titebond original), 2- Titebond III PVA, 3- Polyurethane Gorilla glue, 4- Slow-set System Three epoxy, 5- Ground Hot Hide Glue from J.E. Mosers, and 6- Liquid hide glue from Old Brown glue. Each glue was used in accordance with the instructions on the label for clamp time and drying times for maximum strength. All the joints were then tested on a Instron machine to the breaking point until the glue failed, the wood broke or both. Each joint was measured and recorded as it failed. You can see all the numbers in the article.

The results? 1- The best overall glue was Titebond III with no weakness in any wood or joint fit. 2- Slow-set epoxy came in a close second but was pricier, more difficult to use, and turned out not to be the best choice for gap filling. 3- Elmer's PVA Carpenter's yellow glue was the best value for the money, easy to use and the glue that created the strongest bonds on tight and snug Ipe joints. 4- Liquid hide glue, Old Brown Glue, gave a trustworthy performance and worked very well on oak but was less strong on Ipe. 5- Hot hide glue works best on open grain woods like oak and mahogany and is only a little weaker then PVA yellow glue, was the weakest on Ipe. 6-Polyurethane Gorilla glue had the poorest scores, producing mostly unacceptably weak bonds.

Personally, I like and use many different glues, HHG being one of them. HHG is the only glue I will use for the violin family of instruments because of the obvious need to have a reversible glue for repair purposes (unless the violin is import junk in which case I will use anything that works.) I also use Titebond original in many cases including new construction of guitars, ukes, etc.

Of all the guitars and ukes I have made, I have never experienced any 'cold creep' that some here talk about. Nor have I ever had a guitar come into my shop that has suffered cold creep on the bridge; just lucky I guess. I would suggest that everyone do their own testing on the woods they use and come to their own conclusions.

Personally I would glue the Neck with Hide but there is a technique required to obtain the maximum strength - probably not used in that test. If you haven't got the experience with Hide then you are better off using something like Titebond.

There's another issue...will the repair telegraph through?

The most undetectable repairs I've ever done...including some identical to the broken heel pictured...are with hot hide glue which not only pulls the joint together as it cures, but also takes stain and/or finish better than any other glue line. I'd show you a mahogany heel break that I repaired...in a photo...but I can't see it in real life. It's absolutely invisible. Under certain extreme light conditions I can see it, but only because I know it's there. Nobody...and I mean nobody...would look at this uke and say, "Oh, the player fell on a wet stage, and the uke was broken at the heel." Nobody would see the repair unless I found it and pointed it out. Even then, it would look to most like a normal part of the grain. This would not be the case with Titebond, LMI white glue, epoxy, Elmers, superglue, or any other adhesive I know of.

If you want to to museum conservation level repairs; if you want at least the possibility that your repair work will disappear...learn how to work with HHG.