MIMF

Greetings folks,
I am at the stage (once bridge made and body FP'd) to glue the neck onto my first uke build. Having messed up the location of the threaded inseert, I am proceeding with a straightforward butt joint of the neck to the body, and I would be grateful for opinions regarding the most suitable glue.

The glues I have at home, and am reasonably familiar with
1) Titebond? - not especially good at end-grain to long-grain joins, but is it good enough for this task?
2) Cascamite? - reasonable gap filling (though I am happy with the joint anyway), is the strength there?
3) Gorilla glue? - no gap filling, but probably strong enough if clamping pressure OK
4) Epoxy? - probably the best of the bunch, but the brand I have is the ZPoxy 30 minute - would this be suitable (over, say, West System)? And if so, how do you go about mixing the correct ratio, or is eye-balling the spodges of hardener and resin good enough?
6) HHG? - I have never used this glue, so would need to purchase it and a heat-bucket, and learn how to use it...

Many thanks for any help received,
Adam

Those few uke builder I know of who use a simply glued butt joint all use epoxy. I have no experience with this method, but my guess would be that it is likely to give the strongest hold on the end grain of the neck.

You could also consider what I often do - drill a hole in the end of the neck, soak it in CA glue, and then when dry tap a thread into it. Then glue a piece of threaded rod (allthread) in with CA, and simply use a nut and washer inside the uke body. I use glue, Titebond or HHG as well, but I think the rod does most of the work.

I've had no problem with the thread pulling out of the neck, though it can screw out if you have to take the neck off again.

Epoxy.

Many thanks, you have reinforced my suspicion that epoxy is the way to go.

The problem with the threaded insert was a misalignment of a homemade drilling jig, and using (probably) poor quality inserts that couldn't stand up to the hardness of end grain maple. This I can improve for the next one.

Cheers,
Adam

I find most inserts to be a snare and a delusion. Machine screw threads cut directly into the wood with a sharp tap work amazingly well. You do still have to line up the holes. If you have the $$ you can set yourself up with helicoils and the special tap that goes with them. That really does wonders for the holding power of wood or any soft material.

Glue a dowell in your insert hole and use an anchor bolt

I like the inserts with the "broken" threads. They seem to cut deeper and leave a little more wood around the insert. I also use a little super glue to harden the wood around the insert and glue it in place.

It's possible to make a tap out of the appropriate wood screw to match those inserts. Wood screws already taper at the point, so you don't need to grind or file a lead. Just file a triangular lengthwise groove in the screw to produce cutting edges on the threads, and provide a place for the chips. You'll have to back it out frequently to clear it, but it will work well enough. Epoxy or CA will hold the insert in place once you've cut the thread. Even a mild steel tap will last a long time on most woods.

What is the advantage to Helicoils? I have never used one.

And what, may I ask, are helicoils?
Many thanks for your suggestions, I shall look into the hanger bolts (and helicoils too) for future builds. Despite the awkwardness of size, ukes seem to be a good way of gaining essentially the same skills for guitars, but at a reduced cost, due to smaller size. Plus 5 ukes takes up a lot less space than five dreads or jumbos!
I think I shall also try and source some better quality inserts next time.

Cheers,
Adam

Helicoils are for metal, you need threaded metal inserts for wood, and there are several types available.

David King wrote:I find most inserts to be a snare and a delusion. Machine screw threads cut directly into the wood with a sharp tap work amazingly well. You do still have to line up the holes. If you have the $$ you can set yourself up with helicoils and the special tap that goes with them. That really does wonders for the holding power of wood or any soft material.

This post made me think that helicoils would work in wood too. I have had inserts pull out of end grain mahogany pretty easily so I have been keeping my eyes open for better alternatives.

I always put a half inch maple dowel vertically in my heels so that half of the insert bites into the dowel. I've never had one of those pull out. On one of my first guitars, I had an insert in a maple tongue (with no dowel). Eventually, it split the tongue. I learned a lot on that guitar.

When I use inserts, I coat the hole and threads with epoxy when I run the inserts in, works. I started doing this because I had an insert pull once the first time I torqued up the neck bolt, with gentle torque I might add.

I need to be clear here, many tests have been done on screw holding power in wood, the results are conclusive. Machine screws have a much better holding power in hardwood than wood screws. In fact the finer the thread the BETTER the holding power. This is counterintuitive which is why there is so much resistance to the idea among woodworkers who naturally want to assume the obvious: wood screws are for wood, machine screws are for metal QED. That's fine for kitchen cabinets and out door decks but it's not always going to work for critical joints that are under constant stress like a neck joint.
Read this brief article https://umdrive.memphis.edu/jthieme/www ... 20Wood.pdf for some data.

End grain wood is a problem and the answer is to make some cross grain dowels on a lathe and insert those into the end-grain with copious amounts of glue.

The real problem with the inserts is that they use a wood screw style of thread and to drive them in without wrecking them you need them to fit quite loosely or find a tap that matches the threads to you can get an exact fit. Unfortunately these taps don't generally exist, this is where Helicoils come in. You buy a box as a "kit" and you get the right drill and tap to use with them. The taps are marked with an "STI" suffix to denote that they are for use with helicoils only. ("STI stands for "screw thread insert"). You can read about them here:
http://www.helicoil.com.sg/HeliCoil-STI-Taps.shtml

David, there are several brands of threaded metal inserts with machine threads if you feel you need machine threads. Check Timesert and KEEN-SERT. These are much more reliable that the Helicoil system.

Helicoil is more or less a generic term these days. Glad to know others have taken the concept and run with it.
I've never had stripped neck screws using the usual wood screws on my instruments. I suspect it happens when the screws get overtightened repeatedly by ham-fisted musicians. When I do come across them I use the cross grain dowels as a last resort.
I start by trying to restore the holes with cotton balls and CA glue. That works most of the time.