Glue question for luthiers and the repair savvy

[SabbathFan0220]

So...I'm working on converting a Strat to hardtail buy filling the rout. Before you try and talk me out of it, the work is almost done, so don't bother. I know all the reasons not to do this, but it's an old plywood body and I wanted to give it a shot. I was going to refinish it anyway.

So the wood is already cut (both the body and the filler pieces) and they're a nice, tight fit. I'm using good quality alder with the grain facing in the right direction.

My question is about what glue to use. Some people will use Titebond for every wood-to-wood gluing job, others say Titebond 'creeps' over time. Some people say epoxy is hardest and lasts longer, others say epoxy doesn't belong in guitar bodies and is hard to work with. Some people say hide glue is best because it's reversible, but this going to be permanent...you see where I'm going with this.

I'm looking for a really tough joint that won't 'creep.' It's gotta hold up under tension.

[Zerberus]

Re: Glue question for luthiers and the repair savvy

Titebond or any similar high quality carpenters glue. Iīm not quite sure what people mean when they say it creeps, though...

either way, how often do the fretboards and body wings on your guitars "creep".. thatīs how crappy Titebond and other wood glues are

Epoxy wonīt penetrate the wood fibers well enough to guarantee a staable joint and is unnecessarily expensive in comparison.

Superglues (Aka. Cyanoacrylates), even thick ones, are too thin to be used here effectively unless you really have fine wood tolerances down to a science.

Hide glue reversible??? Total BS, not any more than any other glue. Hide glue is traditional instrument makerīs glue and will glue a lot more thiggs than just wood, but to "reverse" it you need to go through the exact same steaming /heating process as you would with any other glue.... tha main difference being that hide glue also has to be heated BEFORE use as well, making it unfeasible fot most hobbyists anyway. No Idea who fed you that, but donīt eat it

[SabbathFan0220]

Re: Glue question for luthiers and the repair savvy

Thanks, Zerb.

Just so you know where I'm getting my info about 'creeping,' this is straight from Dan Erlewine's Guitar Player Repair Guide...

"Aliphatic-resin, or white glues (Titebond is the most widely recognized)...I don't trust white (or yellow) glue not to move or creep over the years."

Here's what he says about epoxy...

"Epoxy is good for the same tasks as the hide glue, if the right epoxy is used. I use...a 24-hour cure glue, and when mixed, it becomes very thin and able to penetrate as deeply as hide glue."

In the book he uses epoxy for similar jobs to the one I'm doing...
But I don't have any experience with Epoxy (I've been using Titebond for years). So if Titebond is the way to go I'd rather do that anyway. I just want this joint to last.

[David Collins]

Re: Glue question for luthiers and the repair savvy

In this case, it doesn't really matter that much.

Yes, PVA / AR glues can be prone to creep in many applications, but in this type of joint this won't come in to play or be a concern at all. Joints with forces parallel to a flat glue joint can be prone to creep - perpendicular to the faces of a large, square joint such as this, it will not.

Animal glues such as hide glue, fish glue, and rabbit skin glue have much better cold creep and heat resistance, but these issues need not be worthy of much concern here, and getting set up and experienced with their use would arguably be a wasted effort for this one joint. Their reversibility and serviceability are anything but BS however, though that is another topic all together, and not a concern in this joint anyway.

CA adhesives would theoretically work fine, but would not be very amicable to the installation process in this case, and would not be among my likely choices.

Epoxies do indeed saturate the wood fibers better than most other glues, so much so that "starved glue joints" are a more frequent concern with epoxies than most other adhesives.

I'd say you're putting too much though it to it though. You have plenty of bonding surface, and if the plug is indeed tightly fit, you have a mechanical fit suitable of handling the respective loads to be put upon it. The adhesive only needs to hold it from pulling upward, and pretty much any glue will work well enough here from a structural view.

I would personally use epoxy as I'm already set up for it, but the advantages it would hold over a PVA joint are likely only an abstract issue in this case. Gluing to a plywood end grain, an epoxy of typical viscosity would do a better job of saturating the plywood, effectively hardening the surrounding surfaces. Due to the nature of end grain (especially plywoods) to saturate and wick the epoxy in however, a two-step bonding process would be desired. This is a procedure where both surfaces are wet with fresh mixed epoxy, and a second thickened coat (either by allowing it to slightly gel, or adding a filler such as colloidal silica) is then applied to one surface before assembly and clamping. This method ensures good saturation, while also preventing a starved joint. If you have any gaps at all, this is one of the best and only methods to include any gap filling strength, though CA glues can achieve this to some degree as well.

I'd say this may be over-thinking it for this joint however. If you don't already have the epoxies and fillers, a regular PVA woodworking glue will work just fine. The benefits to epoxies over PVA's mentioned above would likely be more theoretical than practical in a joint such as this, and 30 or 50 years from now a joint made with one would likely hold up just as well as the other. The most important part of most joints is the fit itself, and glue is just a tool to keep the fit parts from sliding apart.

Just get some wood glue and clamp it up - you'll be fine.

[Reload in 5]

Re: Glue question for luthiers and the repair savvy

I was going to follow this

http://www.projectguitar.com/tut/tht1.htm

when I was planning to do this. He suggests epoxy for some final gap filling but that is it. I say titebond that sucker in!

[Bludave]

Re: Glue question for luthiers and the repair savvy

I am no builder but one of my closest friends is a Master Luthier. He uses a lot of tight bond. He uses hide glue Only when doing a repair on a instrument that requires it. The older guitars from the 30's & 40's were usually assembled with hide glue. As far as I know hide glue is still used to glue fingerboards on violins.

[SabbathFan0220]

Re: Glue question for luthiers and the repair savvy

Alright, I'm convinced. Titebond it is. Thanks guys.