Furniture Connector Bolts and Cross Dowel Barrel nuts?
- Thread starter Steve-atl
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BR Ukuleles
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Your local hardware store should stock them. If not then perhaps a "Bolt Barn" type of businesss.
Pete Howlett
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UK _ Screwfix carry them
captain-janeway
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Don't know where you live but Ace Hardware carries them. I'm doing a bolt on it for a different type and saw some while I was getting hanger bolts
sequoia
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You could get ukulele bolt on neck parts from LMI here: https://www.lmii.com/neck-installation-inserts/2361-bolt-on-neck-insert-for-ukulele-set-of-2.html
$9.11 USD
$9.11 USD
Moore Bettah Ukuleles
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I like the cross-dowel bolt connectors from Rockler. They seem to be machined better than those found in most hardware stores.
DPO
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I have only ever used lagbolts, I think they are easier.
Timbuck
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Strange world we live in...I have an "engineering background" and I do complicated compound dovetail joints in wood, and the Guys with a "wood working background" use nuts and bolts. 
Pegasus Guitars
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Like Ken, I'm a dovetail person. Bolts are for banjos! If you want to use barrel nuts, why not make your own? Just a piece of steel rod drilled and tapped. Personally, I like the concept of "handmade" to be carried out as far as is reasonably possible. Won't cost you much, and if you have not worked with steel, it actually is kind of fun sometimes.
Timbuck
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Brass is a good materal for making your own cross barrel nuts.
Strange world we live in...I have an "engineering background" and I do complicated compound dovetail joints in wood, and the Guys with a "wood working background" use nuts and bolts.
Engineers have used woodworking joints before, so you are in good company.
"Before 1775 the only way to cross the Severn Gorge was by ferry. Abraham Darby III, an ironmaster working at Coalbrookdale in the gorge, was commissioned to cast and build a bridge (The Ironbridge).
The bridge comprises more than 800 castings of 12 basic types. The method chosen to create the structure was therefore based on carpentry. Each member of the frame was cast separately, and fastenings followed those used in woodworking, such as the mortise and tenon and blind dovetail joints. Bolts were used to fasten the half-ribs together at the crown of the arch.
The bridge was raised in the summer of 1779, and it was opened on New Year's Day 1781"
Max
Timbuck
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And the worlds first motor cycle was also made of wood
jupiteruke
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I no longer use a barrel bolt
I used to use a barrel bolt approach for a bolt-on neck. However, I had two 'incidents' where the neck heel cracked. One was a severe shipping issue, and one was a ukulele on a stand that got kicked over on-stage and did a header. Kind of extreme cases, but they pointed to a weak point since the breakage was the same in both cases.
The issue is that with the barrel bolt one must drill out a hole in the neck heel for the barrel bolt, and then a cross-hole for the neck bolt. The neck heel has the grain running across the heel, so with the removal of the wood for the barrel bolt there is not really much wood left, and the grain is perfect for a crack/split. The issue is illustrated in the first picture.
I have since gone to gluing an oak cross dowel into the neck, and then using a brass threaded insert. I use "E-Z Lok 400-4 Threaded Insert, Brass, Knife Thread, 1/4"-20 Internal Threads, 0.500"" because they have really sharp wood threads. The dowel has a larger diameter than the threaded insert, which means that:
1) The threads of the threaded insert are biting into cross fibers of the oak dowel, not end grain as would be the case if the insert was threaded directly into the end of the neck. Much stronger.
2) Since the insert is a smaller diameter than the oak dowel there are oak dowel fibers that run all the way up and down the heel, meaning that it is very difficult to crack horizontally.
3) There are no voids in the neck heel, solid wood.
This is illustrated in the second picture.
As a test I built a test neck with this setup, bolted it to a block, and then dropped a 3 pound sledge hammer onto the outer end of the 'neck'. It just bounced, the neck was fine.
I used to use a barrel bolt approach for a bolt-on neck. However, I had two 'incidents' where the neck heel cracked. One was a severe shipping issue, and one was a ukulele on a stand that got kicked over on-stage and did a header. Kind of extreme cases, but they pointed to a weak point since the breakage was the same in both cases.
The issue is that with the barrel bolt one must drill out a hole in the neck heel for the barrel bolt, and then a cross-hole for the neck bolt. The neck heel has the grain running across the heel, so with the removal of the wood for the barrel bolt there is not really much wood left, and the grain is perfect for a crack/split. The issue is illustrated in the first picture.
I have since gone to gluing an oak cross dowel into the neck, and then using a brass threaded insert. I use "E-Z Lok 400-4 Threaded Insert, Brass, Knife Thread, 1/4"-20 Internal Threads, 0.500"" because they have really sharp wood threads. The dowel has a larger diameter than the threaded insert, which means that:
1) The threads of the threaded insert are biting into cross fibers of the oak dowel, not end grain as would be the case if the insert was threaded directly into the end of the neck. Much stronger.
2) Since the insert is a smaller diameter than the oak dowel there are oak dowel fibers that run all the way up and down the heel, meaning that it is very difficult to crack horizontally.
3) There are no voids in the neck heel, solid wood.
This is illustrated in the second picture.
As a test I built a test neck with this setup, bolted it to a block, and then dropped a 3 pound sledge hammer onto the outer end of the 'neck'. It just bounced, the neck was fine.
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DPO
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While this is an interesting method, I still prefer simple lagbolts, I am amazed that more people don't use them.
sequoia
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Thanks Jupiteruke for such a detailed explanation on bolt on necks. Nice diagrams too.
I like your testing methods. Relieves stress around the shop.
I like your testing methods. Relieves stress around the shop.
A hero of mine from the industrial revolution, one David Kirkaldy pioneered a similar approach. This is above the door to his Testing & Experimenting Works.
Timbuck
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Paul Bouchard
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If you’re concern is about the threads holding in end grain, you'll have a more secure construction if you glue a wooden dowel where you're thinking of putting the barrel nut. I'd orient the rings of the dowel in line with the length of the neck.
DPO
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Simplicity itself. Wood screw one one end and a machine thread on the other. Works perfectly. Been used on banjos for ever. Never had a failure.
Timbuck
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We call them "Dual Thread Dowel screws" or "Hanger Bolt"in the UK
..and this what we call a "Lag Bolt" 
..and this what we call a "Lag Bolt"
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