MIMF

I am probably going to do a mortise and tenon bolt on neck for my current archtop build. Two horizontal bolts through the head block into threaded inserts in the neck tenon. My question is - are there issues with keeping the fingerboard extension down tight to the top of the guitar? The bolts just pull the neck in horizontally, they don't pull the neck down at all. Do you glue the fingerboard extension down just at the edge of the body, before it starts to lift to float over the arch?

I guess the follow up question is, bolt on necks are the way most larger builders are going, for ease of manufacturing. there was a lot of take-up a while ago with one-off builders, but has there been a trend back towards a traditional dovetail joint at all?

Thanks, Brian

To the first part of your question I'd say Yes, glue the fingerboard extension down. Just make sure that the extension fits well and that you're not pulling it down because of a bad fit to the top.

To the follow up question...I believe that a well done dovetail is superior and more elegant than bolt on. For me the whole idea of archtops is that they come from the violin family and the dovetail is most appropriate for the instrument. Take in mind, I'm an old guy.

I disagree that the neck extension on a bolt-on archtop neck should be glued down. String pressure will keep this joint fairly tight. And gluing it down defeats the purpose of a bolted neck.

Barry, yes you're right. I do bolt on's for cutaway flattops and glue the fingerboard down on them. It's easy enough to undo if a reset is needed...not so with an archtop. Thanks.

No problem. Yep, archtops are fairly different than flattops and present a whole new set of challenges.

Using mechanical metalic fasteners is an old technique. Many early violin family instruments used nails, as did some viols even earlier. They generally were glued also.

I started out using bolt on neck joints but have long since gone with hand fitted dovetail joints. Once you get the concept of how to fit the dovetail it doesn't take all that long, and it is a secure structural joint. You can fiddle around with bolt on joints and spend a lot of time to get all the surfaces to line up and fit properly. Bolt on makes much more sense for instruments where you have easier access to the neck block.

The catch with archtops ('f' hole instruments) is gaining access to the bolts. Easy enough before both plates are attached, but after that you need a very long and fiddly tool to install the screws and tighten or loosen them. Oh, it can be done, but you can build a ship in a bottle too. Why add the extra difficulty?

A side soundhole is not only a feature, it makes bolting necks on that much easier.

Having made archtops with both styles, I now only use a bolt on neck. But joint, not M&T.

Randolph, I fear the joint will not be sufficiently stable with a flat butt joint, and that a 1/2" or so mortice would both locate and stiffen the joint from moving sideways or rotating. Since you've done butt joints, what do you think of that, and what seems to overcome those movements? Just friction?

Brian

I have a hybrid solution: A dovetail joint, cut after the box is closed with router jigs with final fitting by hand. The dovetail fits tightly - I can insert the neck in the body and handle the guitar normally, it takes a "bump" to dislodge the neck. Rather than glue, I use a 2.5" screw through a drilled out strap pin to lock the neck joint. (Most players need a strap pin anyway )

String pressure holds the neck extension firmly down. This solution lets me test the guitar in the white, and then finish the neck and body separately. The details are in the Journal posted under Build Tutorials.

That is very clever, Mike!
Thanks for sharing!
Dan

Brian Evans wrote:Randolph, I fear the joint will not be sufficiently stable with a flat butt joint, and that a 1/2" or so mortice would both locate and stiffen the joint from moving sideways or rotating. Since you've done butt joints, what do you think of that, and what seems to overcome those movements? Just friction?

Brian

The bolts in the head block keep it from rotating. Otherwise, yes. Friction. There is a lot of force on the neck when strung up. I find it nearly impossible to force the neck to move when the bolts are tightened and the strings are to tension. I can't imagine it moving unintentionally.

I know that there are many posts on this forum about using a but joint. In fact I started using it precisely because of discussions on MIMF. I started with M&T joint from the Cumpiano book and the dovetail from Benedetto's book. But I learned a way that works better for me right here.