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So after taking a few years off, I’ve started building again. I had my walnut sides thicknesses to .85”. I was going back and forth on whether I should profile the back side of the sides together or individually. I’ve had problems with double sided tape not releasing, but decided I should be fine if a get rid of some of the tack by sticking it to my jeans/sweatshirt a couple times (on both sides) before pressing them together. I either should have done it a third time or gone with the masking tape/superglue method, because they were still not coming apart very easily. One section in particular wasn’t releasing, and instead, the entire side split along a grain line. I was able to repair it pretty easily, and the repair is pretty much invisible. I used tight bond 3, with the idea that it was water resistant and might hold up to bending better. In hindsight, gorilla glue or something that doesn’t release with heat as easily, might have been the better choice.

My question is, should I take some additional steps to prevent it from letting go before I bend the sides? It’s a 12 fret 000, so the curves are pretty gentle. I consider gluing braces on some of the flatter portion of the sides, even if I have to chisel them off eventually. If I’m able to successfully bend, should I reinforce the crack before final assembly? Maybe some muslin and HHG, or cleats? Or is the current glued state probably going to be ok? I should mention, this guitar isn’t for a customer, and I’m not terribly concerned about aesthetics, otherwise I would probably get another set of sides. Thanks in advance for the help.

Mitch I don't know what additional steps one could take prior to bending a side to prevent a previous crack repair from letting loose.

I'm not familiar with Titebond III and don't know what temp it releases at. Generally speaking Titebond Original or the Extended version are the only two Titebonds that we would ever use in a Lutherie shop of which we have. Gorilla glue is a nemesis for us since we are in the repair business and we only use glues that are reversible.

I understand your thinking that this is a repair and glue joint that will not require serviceability so my only question is will it survive the trauma, and there is a lot of trauma of the bending process. I understand that Titebond III is waterproof but again heat and steam are what is present when bending.

I'm thinking what do you have to lose and give it a try. As for anyone here having a definitive answer for you if this glue will work in this application I don't think so.

If it were me though walnut is cheap and easy to bend, perhaps the easiest wood to bend. So with this said I would probably get some new sides and use the old sides for a dry run with the bender only not dry at all use these sides for practice. I also would be adverse to using a previously cracked side on any new guitar it may be a time bomb. One last thing too finish has a bad way of making us remember our mistakes once applied....

You could put masking tape strips running across the sides like side tapes on the side away from the heat source (blanket? pipe?). They may release from the heat but might hold things in position long enough to accomplish the bend.

This won’t help you now, but PermaBond 825 is a CA adhesive with a melting point of 200*C, so you can repair sides and the repairs will hold…

Thanks Hesh… I think I’ll go ahead and give it a try. I think I knew deep down that the right thing is to get a new set of sides, but was in denial. I just finished bending the uncracked side and it went good. I should have mentioned that I’m using an iron vs a blanket. Hopefully that works in my favor. I’ll give the cracked side a go next weekend, but in the meantime, get another set of sides coming. I’ll most likely go with the new set even if it goes well. I had heard people used titebond 3 for laminating purfling to binding which seemed like a similar application, but better safe than sorry. And I’d be more frustrated if the crack reopened after the guitar is strung up.

Clay- I’ll use some tape when I give it a go. Can’t hurt right?

Meddlingfool- I’ll make note of the permabond if I ever find myself in a similar situation with a more expensive piece of wood. Thanks for the tip.


Sounds like this isn’t a terribly expensive lesson learned, and I’ll at least get some practice out of it. It seems I have precious little time to spend in my shop, so it’s always a little frustrating when you have to take a step backwards. Such is guitar building I guess.

A proper glue joint requires a good close fit and adequate clamping pressure on glue up. If you managed to get both when
you made the repair the joint should "technically" be stronger than the surrounding wood. If it withstands the heat and stress
of bending me thinks it would be good to go.

I use TB3 for glueing purflings to bindings prebend, but have also been finding Lee Valley 2002 to do the trick as well.

That’s the only thing I’d use TB3 for…

Next time you use double stick tape a few drops of Naptha will help the tape release easily. Especially useful when working with thin pieces of wood.


Steve

_________________
Steve Smith
"Music is what feelings sound like"

Ken- after cleaning up the glue squeeze out and some light sanding, I couldn’t tell where the crack was. I decided to leave the inside with the little bit of squeeze out so I could at least see where it was if I needed to reinforce it.

Steve- thanks for the tip. I’ll use that in the future.

Meddlingfool- I wouldn’t typically use it either, but in my mind, people used it to stand up to heat/moisture during bending to prevent separation.

I’ll update this post when I do bend it in case anyone is curious in the outcome.
Thanks again for the responses!

Makes sense! If the purflings hold, maybe the sides will too!

Hi Mitch,
At this early stage in the construction it makes sense to replace the (relatively inexpensive) sides rather than use a repaired set. There are many uses that can be made of imperfect material - purflings, bindings, head plates, etc.
Sometimes you can build a smaller instrument by cutting around the defect, or a simpler instrument that you will have less time invested in and are willing to accept less than perfect. I sometimes build "experimental" instruments from materials I might not otherwise use.
Another possibility is to try something new you might not want to risk a better piece on - maybe thinning one end and bending a cutaway.
I will be interested in hearing how things go, but won't be surprised if it all goes fine.

Reinforce the inside of the side with cloth tape/Titebond III? I infer that the instrument is for personal use, I.e., not a commission, so the builder is free to do as they see fit. If the side survives the bend, all's good. If not, no real dollar cost but a construction dead end.

_________________
Peter Havriluk

For those wondering, I bent the cracked side yesterday, spritzed with water with no issues. I’m actually kind of surprised to be honest. Now I need to decide whether to roll with it or track down another set of sides. Thanks all for the encouragement to at least move forward, even if it were for practice. After 10 years, I definitely benefited from a dry run if nothing else.

If the repair held and the crack doesn’t show, is there actually a problem with those sides?

Other than having a repaired crack on a new guitar, no. As Hesh pointed out, there could be potential for it reopening, especially after it’s been steamed and bent. Even though this one will likely stay with me, I’d hate to have to attempt a side repair once it’s all finished in a few years. That being said, I’m anxious to keep moving forward with the build vs finding a decent match to the back. Walnut is easy enough to get but air dried stuff that looks cohesive is a little harder.

Titebond III was a good choice for this. I would have been surprised if it failed during bending. As others have noted, many builders use it for purfling assemblies. It's also a good choice for building up a stacked heel to be used in a dovetail joint. There are plenty of glue seams on a guitar that will never need to be opened up. Titebond III leaves a darker glue line, so it's best to limit its use to darker woods. Walnut is a perfect application. Here's a blurb from the manufacturer about its temperature and moisture resistance:
"Type I testing involves cutting the 6" by 6" assemblies into 1" by 3"
specimens, boiling them for 4 hours, then baking the specimens in a 145˚F
oven for 20 hours. They are boiled for an additional 4 hours, then
immediately cooled using running water. The specimens are sheared while
wet, and the bonds must pass certain strength and wood failure
requirements to pass the Type I specification"

This is a great example of how different folks may deal with risk differently and no one is wrong here for their own sensibilities.

I'm not willing to take a chance with someone else's stuff and experience with Lutherie so I tend to be super cautious and perhaps the word could be conservative here. And I can be wrong and may be here where Titebond III may do the job fine including over time. If so I stand corrected.

Gluing purflings and repairing a cracked side is not however the same thing in terms of what loads will be encountered in the life of the instrument especially when and if it is ever permitted to dry out. But I digress and don't want to be insincere in my own thinking here.

However for my own piece of mind and my desire to believe that we should be able to build heirloom instruments with best practices I would still be unwilling to use the cracked and repaired side just for peace of mind reasons.

I also immediately when reading the OP's post went back and saw what wood is being used here and said to myself this is easily replaced and the cost is mouse nuts.

My role here on the OLF is a bit different too. I advise people how to do things I am not here for any other reason. So I try to keep it simple and clear since things get convoluted. Titebond III has zero applications in our repair shop and frequently we have to remind people on the OLF that all the different flavors of Titebond are not all suitable for Lutherie. Titebond II is one such example. This is why I always refer when I do to Titebond "Original" as "Titebond Original" wanting to be crystal clear and provide good advice.

So I may be wrong here and if so I admit same but I also may not be wrong for anyone who is as careful as I am. My nightmare would be someone coming back two years from now and telling me that based on the poor advise that I gave the hopefully heirloom instrument that they built and gave their only son for their graduation from University the crack opened back up and what do they do now.

That's my nightmare and I would suggest to anyone else who cares that there may be a difference in what you are willing to try out and live with yourself and what the consequences to someone else may be and if they would be completely let down and even devastated by what might result.

A long crack on a built guitar side is not an easy repair either by the way especially for someone not tooled up to do repair and who has never done it before. This was on my mind too.

This is also a good opportunity to bring up something else related. I'm posting the first tutorial I've done in ten years here on setting-up steel string guitars. I'm excited about it too and trying to do my best with it for you guys. It gives me some very welcome purpose too which is a good thing these days for me personally. Did you know that everything I write gets a specific review, every word and edit for the idea that I don't want to be telling someone to put their hand in a table saw.... Or in other words I actually do vet what I write for the idea that someone could take what they believe I said and hurt themselves somehow.

Can't have that, ever.

Before I retired from a BIG company when we would buy other companies we had what we called "assimilation sessions" where the newly added folk to our community of Borg.... were assimilated into our ranks but not without some indoctrination. I would lead some of these sessions and call on the people in the room to tell us what is "job one" for insert-our-company-name-here? Invariably someone would quickly answer making money. And in variably I would tell them that they are wrong. I probably did 15 of these sessions and no one ever got the answer to this question, what is job one correct.

The correct answer was shielding the company from unwanted liability. Our company was so large that multiple liability lawsuits were filed against us every day by every slip and fall artist or bring your own cockroach to the restaurant type out there.

Now you have some insight into who I am as a person. I'm unwilling to accept risk for other peoples stuff or even them. Not my bag.

So with all this said I could be wrong for you but now that you have had the opportunity to understand what's on my mind when I help someone here, being uber responsible, accurate and safe it just may be that I am too much of a wussy for some. But I've also never had an OLFer come back later and tell us that what I advised them to do or not do harmed them in any way..... And when it comes to the handling of the valuable personal property of others I freely admit, guilt as charged. And my repair clients love that I won't take risks with their beloved stuff nor should I, ever.

With all this said Eric is of course correct provided that your side never splits again. Tick, tick, tick...... Kidding of course, kind of... But for me I would still replace the side just to be sure and because it's your's, not mine and I am unwilling to take risks with the valuable personal property (or safety) of others.

Hesh- I very much appreciate your well thought out reply. Both the first and the second. If I didn’t think it had merit, I wouldn’t be wavering so much on whether to use it or not. Even though I’m not a corporation shielding my company from risk, my time is still valuable and really don’t like the idea of an assembled guitar full length crack repair. Again, this one will be my own, but same answer. At this stage, a new set (back and sides to get a good match) is only 80ish dollars and a little extra work. Mostly rejoining a back and a couple hours in side bending. It’s definitely a risk reward calculation.

Eric-Thanks for the info from Titebond. That’s more reassuring.

I’ve got some time before I’m moving forward with the build, so I’ll give it some more thought. I mostly wanted to give a follow up for people who were interested in the outcome. It’s possible I won’t know the right answer unless I move forward and see where it stands in 10-20 years.

My opinion is that if that crack was going to reopen, it would have happened during the bend. It didn’t, so it almost certainly won’t. And a few side splints for good measure.

While I am generally risk averse as well in my professional life, and most likely wouldn’t proceed with that out of my shop for reasons stated above…this is an early instrument for you and you’re almost certainly going to encounter most of the same problems down the road (geometry, neck angle, good binding channels etc.), as everyone does, so it’s a woodworking project where completion is priority over perfection.

Press on and learn…:)

Yep to what Ed said, successful joinery and maybe shouldn't be considered a crack repair as such would be in a finished guitar.
I look at it as more akin to the joint you'll have down the middle of your top:) In the end you'll have to please yourself, piece of
mind and all that. Sure, walnut is relatively inexpensive. I wrote the word "cheap".... somehow it didn't look right:(

If I wasn't trying to build for a client or my "magnum opus" I would probably add some cleats to the inside and build a simply ornamented guitar using other low cost materials where I wouldn't sweat other mistakes and repairs that almost invariably happen in guitar making.
But then, I hate to waste things.
I once laminated a set of sides opposite of what they should have been - the "tail end" of one side was where the "neck end" was on the other side. The sides laid around the shop for over a year and I finally decided to use them with a back set that had a small piece patched in near the center seam. It was kind of an experiment to see if I could squeeze a size 1 set down to make a size 2 guitar. It was a "no sweat" build and turned out to be one of my favorite guitars. No one has commented on the mismatched sides or patch on the center seam.

The argument that the side if it's going to come open again would have not survived the bending process is not a good argument in my experience Ed. The bending process may have weakened things to just before the point where the joint fails and it's not going to regenerate or repair itself.

A glued crack failure is a bit of a different animal too in how they fail. The crack need only pull open in one very small spot and that open spot acts like a zipper to encourage the rest of the crack to come open.

I can't tell you how many guitars we see in the repair world that a previous repair may have survived being delivered to the customer but then the first RH swing it encounters or the tenth.... after that it splits open.

Have you guys ever repaired a full length side crack and made it or had to make it invisible? On a scale of 1 - 10 for crack repairs it's one of the very most difficult to do well and a big can of worms. Alignment is everything and access particularly way in the box sucks....

I'll add that it will be a previously repaired side crack with old glue in it contaminating the crack when and if it comes open again making it even more of a can of worms to have to do twice.

I also don't agree that completing the project is most important even if there is a potentially critical flaw in the assembly that could take the entire instrument out of service and cost hundreds to have professionally repaired and finish touched up. This it the OLF not Boeing Kidding of course and then the door plug blows out....

Doing it right even if it means doing it over has been a long standing tradition on the OLF and of course everyone can do whatever quality of work they wish. But if it were mine I would be replacing the side.

And one last point too.... I never intended to be a professional Luthier and I also never intended to sell my guitars. I was just building one for me to have some fun. Stuff happens and you may find your stuff going out into the Wild West of having a thing called a customer or a loved one who needs a gifted guitar someday even if unexpectedly. Yet more reasons to do it right, do the best we can, always.

I just got home from work and had a thought at work that I wanted to share about doing it right even if it means doing it over.

This is the OLF not Boeing..... Sorry couldn't resist.

Yours the proper advice, mine the practical…

Sure and it's very much a personal sensibilities thing where we all may see this a bit differently.

I'm surprised at how much walnut is now when I was building full time 15 years ago it was dirt cheap and everywhere. That was part of why I would replace too, easy to get and cheap, some of my favorite things