A query regarding glues.

[Kalimna]

Greetings folks,
I wonder if anyone could suggest the most appropriate glue for gluing end grain to long grain as a butt joint. Specifically for gluing the neck onto body of the ukuleles I'm building.
The options I have at home (without making further purchases) are :
Titebond I - least favoured option
Epoxy (Z-poxy 30minute) - probably preferred option, though is there a significant difference between this and West? Also, how do folk ensure correct mixing ratio? Just eyeball the splodges, or something more scientific?
Cascamite - unsure
Gorilla glue - no better than Titebond

I am happy with the mating of the surfaces, but understand epoxy to be the best at gap filling.

Cheers for the usual good advice,
Adam S

 

[dzj]

Luthiers typically use hide glue.
If the neck would ever be in need of re adjustment, a reversible glue would be the way to go.

 

[Kalimna]

Thanks for the suggestion. I know *some* luthiers use it, but it is far from standard practice. It's not a route I shall be going down.
And as far as readjustment goes, a bolt on approach is superior to HHG in many respects, but I pineappled the threaded insert so that isn't happening either.

Cheers,
Adam

 

[Mike.S]

Epoxy (Z-poxy 30minute) - probably preferred option, though is there a significant difference between this and West? Also, how do folk ensure correct mixing ratio? Just eyeball the splodges, or something more scientific?

I've used the West system and two suggested methods are:

1) buy the system dispensers (push buttons/plungers on the containers) that squirt out measured amounts.

2) buy plastic measuring cups - clear plastic with measurements on the side. This is what I used - you just pour the resin and hardener in up to the marks. Appear to be the same as the plastic measuring cups painters use (which are cheaper). The hardened epoxy doesn't adhere so you can re-use the cups if you're careful.

 

[marcros]

i would rule out pva and gorilla because it will creep. I have no knowledge of your application, but have seen cascamite used for tasks because it doesnt creep. It is slow setting though in my experience.

could you use a syringe for the epoxy and hardener?

 

[Jacob]

My one effort as a luthier was making an actual lute, about 30 years ago, using PVA throughout. Still in one piece, no creeping of PVA there, or anywhere else in my experience (i.e. several tons of joinery).
Must learn to play it one day.

 

[Mr T]

I think an epoxy is your best bet. I use a syringe to measure out small quantities of West System. Using the dispensers usually means a load left at the end of the job.

However, do you think any glue will be strong enough for an unreinforced butt joint for a eukele kneck, the forces there must be quite strong? You say you pineappled the reinforcement. If it's just loose could you use thickened epoxy to fill the rod hole?

Chris

 

[andersonec]

I would have thought some sort of mechanical reinforcement would be in order in that situation.
The kitchen worktop manufacturers use D4 PVA, this is the industrial version of the normal D3 PVA commonly available, available from Toolstation.

Andy

 

[MIGNAL]

HHG (or bone glue) is the best and was used for similar joints on countless thousands of Romantic Guitars. Actually it was a very shallow mortice (virtually the thickness of the ribs + 2 mm's) but the mechanical aspect of the joint isn't very great at all. Size the end grain and HHG is unbeatable. There should not be the need for reinforcement of any kind, although there is another type of joint that could be employed that uses a spline. Romantic Guitars are at much greater string pull than any Ukulele. In fact if I made Ukuleles I would be using the shallow mortice type joint all the time. I can't think that a Neck reset is all that common on a Uke.
Cascamite is also extremely strong but you will never get it apart (if that bothers you). The crucial aspect of gluing any end grain is stopping the wood soaking up all the glue. A starved joint is something you have to avoid, which is why HHG is very good for this situation - the glue sticks to itself.

 

[Kalimna]

Many thanks indeed for your suggestions.
With regard to mechanical reinforcement vs plain butt joint, there are several luthiers who would use a simple butt joint alone with a steel string guitar, which has considerably more tensile loading than a nylon strung uke. So I know that won't be a problem.
With regard to HHG, I suspect in the future I shall purchase the necessary equipment to use it, but with no experience in its use, and only requiring a small amount for a single join, I shall give it a miss this time. I understand the benefits of HHG, and certainly respect the reasons for using it, but not this time.
Epoxy - I like the idea of syringes, it makes sense, if the resin/hardener isn't too viscous!
PVA/AR - I remain unconvinced that this is suitable for this particular joint. The creep issue I would agree with Jacob, and maybe the D4 would be suitable. But most situations it is likely to be used in woodworking/carpentry (however many tonnes-worth ) are under compression/shear rather than tension as is the case with the uke neck.
Cascamite - am thinking a second choice to epoxy.

Mignal - thanks for the explanation of why end grain fails. Your explanation makes sense with regard to sizing, and HHG sticking to itself.

Again, thanks all,
Adam