Bolt on neck method

[Jim Baker]

I recognize that most builders frown on a bolted neck joint, but let's just say for a moment that we all recognize it as an accepted method, what is the best hardware to use?
My stewmac campfire kit came with a 3/16" lag stud but I have read of using a glued in insert in the heel and threading into that. Are these inserts available?

Any opinions? Thanks.

[Jim Baker]

Perhaps to answer my own question I did find such an insert at McMaster Carr.

http://www.mcmaster.com/#catalog/116/3267/=6egnhl

[big smiley guy]

On guitars I've always used a bolt on neck using threaded inserts. Most "real" hardware stores will have a selection to choose from. I use 1/4-20's for guitars but there are smaller sizes available that might work better for a mandolin.

[Jim Baker]

Thanks Smiley. I'm thinking 1/4-20. I looked at some hardware stores here. I haven't checked Lowes yet. Lee Valley has lag studs that are used as funiture hardware, but I think I like the idea of an insert.

[bennyb]

Howdy Jim,
I haven't done any bolt on necks yet, but I'm thinking about it. I'm probably going to copy mottola's technique. He's quite specific about the hardware. (Maybe you already know that site?)

benny

[Charles E.]

Jim, here is a mock up I use on my instruments using knock down furnature hardware. Screw inserts dont like end grain maple. Screws and 10mm barrel nuts as well as screw inserts are available at Home Depot and Lowes

[billhay4]

Charles E. has it right.
The barrel nuts are a better solution IMHO.
Bill

[Jim Baker]

Thanks guys. I do like the idea of the barrel nut. I will check to see that I can make it work. I could easily make one if I can fit it in. The hole would need to be drilled blind from the top down I'm thinking.
Since I will be using 2 bolts I should make one barrel nut with two threaded holes I assume.

Benny: Good information. I will check to see if I can get that type of insert. If I can get the inserts they would be easier for me to install.

[Charles E.]

Jim, with the barrel nut you drill it from the neck heel, not the top. the hole is then covered with a heel cap.

[Rob Grant]

Why?

I can imagine a slight advantage with a guitar since a neck reset is a fact of life with most guitars, but why a mandolin?

[pelone]

Jim---I have used the McMaster Carr slotted drives on a mando as commented upon by Smiley and Benny B. I found, as Mattola shares, that a secure anchor is created when inserting 2 of the drives in the pilot hole and then backing out the bolt results in a nice alignment when the hex headed nut is then used from the sound chamber side. I further used glue to insure a solid and secure anchor. I have not had any separation at the heel due to tear out in end grain maple as mentioned by Charles E yet but perhaps I am just fortunate. However, the end grain concern/problem does occur to me to be valid and consequently I will likely use the barrel nuts as the method seems to be simple and elegant. I like the barrel nuts.

I suppose that "traditional" builders do not approve of bolts because it was not done that way historically speaking and metal bolts seem to be counter to the trade. However, if metal were that onerous we should then abandon metal strings, metal tuners and heel plates. Please post photos of your project if possible. Happy Building.

[Jim Baker]

Thanks guys. My project is a 21" scale octave mandolin. Engleman spruce and big leaf maple. I'm just at the stage of completing the neck joint and I need to fix the neck so I can verify the angle.

[Charles E.]

Jim, that looks great!
A good friend and fellow builder were dicussing using an elongated 1/4" hole in the neck block of an octave mandolin with a floating fingerboard extension. You could adjust the height of the fingerboard over the body to affect the string heights. He built at least one instrument that way and said it worked well.

[Charles E.]

Why?

I can imagine a slight advantage with a guitar since a neck reset is a fact of life with most guitars, but why a mandolin?

Rob, that is a good question, I suppose it is a cary over from my guitar building days. It is really not easier then a dovetail, you still have to be very accurate cutting the mortise and tenon and drilling the holes. It does have great mechanical strength however. Of course it limits you to oval holed instruments but that is all I build. I guess it is what I am comfortable with and it works for me.

[Jim Baker]

Hmmm....... I didn't think of that possibility. Do you think I would have problems with the unsupported extension because of curvature from installing frets?

[Nick Triesch]

Many famous guitar and mandolin makers use bolts. Weber does. Gibson and Flatiron did. James Goodall makes some of the best guitars in the wrold with bolts. Collings mandolins do not use bolts but use the mortise and tenon like Weber but without the bolts. Nick

[fatt-dad]

on the matter of "using bolts." Flatiron used screws to act as internal clamp to hold the glue while it dried. Flatiron has a M&T glued neck joint.

To me a "bolt-on-neck" implies you remove the bolt and voila, the neck comes loose. Flatirons and Webers are not like that. On guitars, Martin is not like that either.

I'm not a builder, but have learned about this stuff somewhere.

f-d

[big smiley guy]

On bolt-on guitar necks that many guitar builders use the fingerboard extension is glued to the top of hte guitar but the neck itself is only attached by bolts. It's a pretty simple procedure to removed the neck. I'm used to using white glue for the fingerboard extension over the body since it's not an integral joint and that makes it easy to remove without having to use too much heat.

[Jim Baker]

If I glue the extension to the top I will have to make a wedge. I read somewhere that there can be problems with the extension if it's not gued down. Any comments on how it may affect sound?

[jim simpson]

I though this was interesting of Martin Guitars to try:

http://www.babiczguitars.com/martin.shtml

There were certainly examples of this concept from earlier in the century.

I think the best bolt on design would be one where the finish isn't disturbed should the neck have to be removed from the body.

[Jim Baker]

Oooh! Now that's hi tech. I'm guessing the fingerboard extension floats in an opening in the top. Not an option for me I'm afraid.

[Kshot]

Looks Great Jim! Keep us up to date on it.

Keith

[Dfyngravity]

How about Graham McDonald? I think he uses bolt on necks pretty successfully.

[Jim Baker]

Actually some of my design ideas came from Graham's bouzouki book.

[Graham McDonald]

I think threaded inserts are the simplest way to go, but I would be a little concerned screwing them into the endgrain of small tenon you have. The ones we get here have an internal metric M6 thread and a coarse external thread. I have found a 9mm hole works well as well as 5 minute epoxy on the threads as the insert is screwed into place, but your inserts with imperial threads may be different. Trying a couple out on some scrap maple with different sized holes might be safest. One way to keep the fingerboard extension stable without gluing it to the soundboard would be to gluing a couple lengths of CF bar (like 1/8 x/1/4") into the neck either side of the truss rod so it extends a couple of inches from the heel (towards the nut) and along most of the length of the fingerboard over the body. Matching slots can be routed or chiseled into the soundboard and neckblock

I have found it easier to fit the neck before gluing the back on. You can mark the position of where to drill the holes for the inserts with a bradpoint bit without having to work through the soundhole. Of course, if you glue the back before the soundboard, that's not going to be much help.

Looks good!

cheers