MIMF

Hello, new here this time around, but I was on the forum a bit quite a few years ago. I am building a kind of hybrid archtop and I am not sure what route to take with the neck joint. The guitar will be a fully carved traditional cedar top, X-braced with a 2" thick fully chambered mahogany body. It will probably have one floating neck end pickup or a pickup routed into the top, haven't finalized that yet. The body will be a billet of mahogany, 2" thick, fully carved out with 1/2" thick sides and a 3/16" floor, and with the neck block carved from the billet, so it will be end grain where the neck joins. It will have a venetian cutaway. The neck will be two piece laminated mahogany, cut from the same billet as the body, possibly I will add a center lamination of curly maple to match the planned headstock lamination.

So, with the cutaway making the neck block kind of skinny on that side and with the end grain mahogany, I was worried about using a traditional dovetail joint, which is what I would actually prefer to use if possible. I was even thinking of offsetting the dovetail away from the cutaway side to achieve more neck block thickness. Other thoughts have been a Les Paul style tenon, or even a tenon with bolt fixture. The body thickness at the neck joint will be around 1 3/4" not counting the top, so I figure the dovetail can be up to about 1.5" deep. What are your thoughts and ideas about this sort of thing?

Thanks very much for any ideas you can share with me!

Brian

This guy posts over at the OLF and builds some beautiful instruments. http://www.sankeyguitars.com/spur/

I really dig this model and the neck joint solution. Simple, elegant.

I looked at that site, he is in my old home-town, but I couldn't find any detail of his joint except for "bolted to the face", which I didn't understand. After spending some time in the MIMF Library I've decided to go with a bolt-on neck either using barrels or the LMI inserts. I have some hard birds-eye maple which I may use as a center strip in the neck, and I'll access the bolts through the tail-pin with a long hex wrench which I'll make. I was quickly reminded of a Hagstrom D'Aquisto oval hole arch top that I used to have, which had a bolt on or screw on neck. I didn't like it much, it wasn't a well done joint and I was forever tightening and shimming it but you had easy access through the oval soundhole. I'll take notes from that guitar and make my tenon almost self-supporting from an alignment point of view and just use the bolts for strength. The Hagstrom joint was very loose and relied on the bolts for everything. It had three bolts - two inside and one through the strap button on the bottom of the heel.

Brian

Hi Brian,

Pictures are worth a thousand words, especially if one is not so good at writing. I'll attach one.

I don't think I'll be doing this exact configuration again. It was really tricky to get the bolts into place and tighten them through the soundhole, and of course I had to do it a few times to get the neck angle just right. I think the next time I'll do a shallow mortice again but put the bolts all the way through from the back (maybe with a nice bushing or insert for appearance) and lighten up the neck block by carving away as much as I dare.

If you do a good job with the mortice and tenon, the bolts (and more importantly, the threads on the neck) won't be under too much strain. I only used two bolts in this instance and it's plenty strong enough. I use 1/4-20 knock-down hardware from the local home store. I generally don't use inserts either; just drill and tap into the neck (I would only do this with maple or walnut or similar hard wood), flow in some liquid CA to strengthen the threads, then tap again with a bottoming tap.

For this project if I were you I think I would do a mortice-and-tenon joint, and bolt in on from the back, not from the inside. But that's just me.

Thanks for stopping by to talk about this neck attachment solution, Michael!

I figured you did some sort of neck pocket, like an electric, but we were left guessing as to what was going on inside. I like it a lot, and yes, I'll be stealing this idea in the future.

I'm sure there are ideas that are better worth stealing (like I said, it was a pain to assemble) but by all means go ahead.

Brian,
I understand that you will have a somewhat shallow body on your instrument, but have you seen any of Dave Stewart's work in these forums?
Dave does bolt on necks with most or all of his archtops and I expect you can find his threads in the archives. Also, check out the very informative tutorial he posted quite a while back on OLF:

http://luthiersforum.com/forum/viewtopi ... 17&t=16049

Patrick

Through that small-ish soundhole in the upper bass bout, yes, I can see how that would have been a challenge. But I would consider doing everything you did, except for two holes in the back for the wrench. This is a joint that I've thought about before, and it's very affirming to see someone pull it off so nicely. If one were extra tricky, you could even make it adjustable for neck pitch (think Doolin's adjustable bolt-on joint oriented horizontally).

Thank you all for great input, I appreciate it. The neck joint that I was planning is almost identical to Dave Stewart's, so it's nice to see that I invented something that someone else has had success with. Since I am planning to basically rout out the interior of my body adding a mortise at the neck will be dead simple (I will actually mill the body out with a Bridgeport, I'm more used to doing this with metal than wood but a Bridgie should be a great plunge router...). I was going to cap the end of the mortice inside the body with hard maple for strength and install the bolts before I glue on the top (with capture washers to keep them in). I was going to fit the neck and get the angle before final gluing of the top as well, and before shaping the neck fully so it would be easy to work on the tenon with the neck blank still squared up.

Early days yet, but I hope to get most of the mill-work done before winter, my wood machine shop isn't heated...

Brian