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I got this bright idea to use two 10-24 bolts to attach the neck on my next project. Consensus seems to be that 1/4-20 is a mite bit of overkill. Except that guitar manufacturers use 1/4-20 bolts and they make thousands of guitars. I can't see a manufacturer spending a dime more than necessesary on hidden hardware and I'm guessing that hardware is sold by the pound to manufacturers.

Have I missed a signal I should have caught?

Thanks!

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Peter Havriluk

I've used two 10-24 bolts (with washers) on all my guitars and octave mandolins. The builder I learned from used them for many years. No problem. If you do the math, the load on the bolts in the neck joint under full string tension is minimal. 10-24 bolts are more than up to the task.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Agreed - - - so why the persistence of quarter-inch bolts?

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Peter Havriluk

Ubiquity, maybe? 1/4-20 hardware is everywhere, in all types of bolts, nuts and inserts. Less so for other sizes.

Because 1/4-20 barrel nuts are widely used in knock-down furniture? It's easy to get barrel nuts that size, and easy to use them.

Reasonable enough idea, barrel bolts. But I don't know of any manufacturers that use barrel bolts of any size.

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Peter Havriluk

What is the cost difference between 10/24 and 1/4-20?

pennies

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

What's a barrel bolt? A barrel nut is a length of steel round stock with a hole drilled and tapped perpendicular to it's axis. I don't know if any manufacturer uses them on guitars, but a number of individual makers do.

This is what I've always called a barrel nut, and I use these along with 1/4" hanger bolts to mount necks:

https://www.mcmaster.com/90835A666/

Dave

https://www.homedepot.com/p/Everbilt-3- ... /204806602
I find these very helpful for bolt on necks

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I've used those for years on banjo necks as well as guitar necks--they can take a bit of care inserting straightly in softer woods especially, but work great from my experience. I ended up switching to hanger bolts and barrel nuts as a result of reading a thread on this forum some time back for guitars. Still use the inserts in John's link for banjos. The concave surface of the inside of a banjo rim doesn't work well for barrel nuts, but the flat surface of a guitar heel block does. Both ways work great.

I've used the 1/4" connectors because they're easy to obtain. A lot of (especially) bluegrass banjos have used a smaller diameter hanger bolt without problems for a long time.

Dave

I use 10/24 furniture bolts.

I recently found these threaded inserts that are designed to hold better in hard woods. The exterior threads are very sharp and thin. Should be more resistant to pull out. (I had one brass insert start to pull out when I over-tightened the bolt.)

Inserts

Barry,

I install a maple dowel in my heels with the center a half inch in so the edge is 1/4 inch in. I use the 5/16” threaded insert which embeds itself half into the maple dowel so that there is more than end grain holding in the insert. Then (I’ve heard that anything worth doing is worth overdoing), I put a drop of ultra thin CA at the edge of the threads outside the insert. I’ve never had one pull out but I did have one twist out when I removed the bolt before I started using the CA. I’ve handled the large inserts like you show, but I was worried that they might not be as string as the smaller one given that the required hole is bigger.

When I do one where I’m really worried about strength, I use a 1/4” hanger bolt.

Back to the original thread: I use 1/4-20 bolts because they are easy to get, easy to handle, and are certainly stronger than they need to be. Standardizing everything around that size makes it easy to have what I need for jig making, tools, nuts, taps and dies, etc.

ballbanjos:
I've never seen those. It looks as though it's bottom tapped and uses a hex key to turn it? I get the the 'sidewinder' type I described at the local hardware store, and the label on the drawer says 'barrel nuts'.

I always worry about splitting wood when driving in the sort of threaded insert John shows. They use a wood screw thread, and I have made a tap out of a wood screw for those when I want to use one. I'll note that that's the sort of fastener that Taylor used to use, and I have the remains of a Taylor 12-string neck where the heel split through the upper insert.

When using the type of barrel nuts I do I've found it good practice to install them in the heel of the neck in a hole that is drilled perpendicular to the fingerboard plane. I used to use short ones in holes running from side to side though a tenon on the heel. One of my students made one that way. He hit the head on a protruding beam in the ceiling just after attaching the neck and the heel split across just below the neck shaft. The neck stayed in his hand, and the body dropped to the floor.

I should have known better. The FAA makes the point that hardware in a wood structure is likely to be a stress riser. Bolts, such as those used to attach a wood prop, should fit tightly enough in the holes that they need to be tapped in with a hammer. This ensures that any sideways load is spread over the whole width of the bolt shaft, and not concentrated at a line where the metal hits the wood in an over sized hole. In that case there is a sideways force tending to split the wood along the length of the bolt. That's what happened to my student's guitar. He had over tightened the screws holding the neck, which produced a splitting force in the heel, and all it took was a bit of a sharp blow to start the crack.

With the barrel nut installed in a hole that is perpendicular to the fingerboard face any splitting force is trying to open up a vertical crack in the heel. Since the neck has a tenon that goes into a mortice in the body the two sides of the heel can't move far; even if the neck does split it's retained: the assembly 'fails well' when it does. In practice I've never had that problem.

I'll note that the 'barrel nuts' I get are labeled as '3/8" diameter', but, in fact, they're 10mm. 25/64 is too small. If you use a 13/32: drill the hole will be over size; it usually is even with a 10 mm, ad even a letter X is too big. I often 'bed' them with CA after getting the hole as tight as I can. As Obi-Wan never said: "Spread the force, Luke"

"I've never seen those. It looks as though it's bottom tapped and uses a hex key to turn it?"

Yes, that's right. They thread onto 1/4" hangar bolts that thread into the heel. A replacement for a regular nut, but a bit neater.

Dave

In old butt joint glued in necks in old Levin guitars, I always add one screw through the neck block into the neck heel. I use a wood screw with deep and straight threads, as in the picture. The hole in the neck heel is drilled with a drill bit that is as thick as the center of the screw. Before using it, I put some thin Superglue into the hole, after that I put some paste wax on the screw and in the hole. The screw is screwed in and out a couple of times to make it easier before securing the neck.

With a single wooden screw like this, the added wight and the loss of wood in the neck heel is small.

Edit: Forgot to mention that I also drill and glue an 8 mm round birch rod through the middle and along the neck heel, that gives the screw more "bite".

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New will change the old,
turn to ashes or gold

http://www.gammelgura.se

I've used a T-nut on the inside of the block and a long 10-24 bolt to secure necks. On my nylon string 'test mules' I have the bolt coming from the inside and a wing nut at the heel. I use a stub fingerboard on the top, with a couple of holes in the end for 1/16" locator pins in the neck fingerboard. The heel just floats, and I usually put a stop block in the gap between the heel and the body so that the neck can't be pulled backward, which frets the strings out. You can push it back with finger pressure on the lower end of the heel. There just is not that much force on the bolt, and the biggest problems I've seen so far are from over tightening it.

I use Threaded inserts in the Heel stock with 10-24 internal threads ( 2 ) and I usually add a touch of glue on fb extension , Seems to work well for me

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The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
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Same ones but in Stainless Steel

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

I like 10-32 for attaching the neck heel. I built two guitars (in 1988 and 1990) with an adjustable heel, and both of those used a single 10-32 hanger bolt. For strength, I drilled the heel vertically and installed a 3/8" or 1/2" maple dowel. Both of those guitars are still in service.
IMHO, barrel nuts and 1/4 -20 bolts are unnecessarily heavy and way overkill when strength is considered. Threaded inserts can pull out (end grain insertion) unless a cross dowel is used. The way I look at it, the insert only requires a larger diameter dowel with no real advantage over the hanger bolt.

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John

I like the hangar bolt idea except that it would get in the way of flossing the neck when an inevitable neck angle correction is necessary.

For my "travel" guitars I use a single 10-24 socket head cap screw recessed in the heel and a T-nut mounted in the neck block. I also have a couple of alignment pins in the block near the soundboard side the neck can pivot on to allow for adjusting the action. The smaller diameter cap screw works fine.
For regular bolt on necks I use a single 1/4 - 20 furniture bolt low in the block, with a soft wood insert in the heel. The soft wood inserts have longer "broken" threads that bite deeper in the sides of the hole and also allow the wood in the "broken" areas to swell back together and when the insert area is wetted with thin super glue it makes a strong bond that resists "unscrewing" the insert when removing the neck.
https://www.ezlok.com/e-z-hex-threaded- ... -soft-wood

I avoid stainless steel like the plague when using small diameter fasteners under tension. I have had them gall and seize up even using reasonable care when trying to unscrew them.

I goofed. I stopped by the local hardware store to look for 'barrel nuts'. The didn't have them, but I found that what I'd been calling barrel nuts all these years are in a drawer marked 'cross dowel nuts'. Makes sense. My bad.