The Neck Block - Mortise

The neck block is essentially just a mortise that is fixed into the correct position inside the top end of the guitar (at least in the style of neck-fitting I'm going for with this build). Some would say that the best mortise is one that has been cut from a single block of wood, taking the laborious time to chew - er, I mean gently carve - the notch by hand. Well, I'd like to do that, but my tools are limited. I chose to construct the block out of sections. This had the advantage of giving me the opportunity to ensure that the side pieces of the mortise were exactly where they needed to be to accept the tenon perfectly.

Didn't get pics, but I cut the side pieces first and clamped them tightly against the sides of the tenon. I then glued the end piece onto the sides, to create the semi-box shape. After that dried, I removed it from the tenon and glued the bottom piece on. The bottom is maple, the same maple the back will be made from.

Test fitting is always a good idea. I used small clamps to hold the mortise directly under the slot I cut for the neck join on the guitar top. The neck slid down nicely into place, and when I checked for alignment I saw that the neck was directly in line with the centre line of the guitar. Yay me!! The only issue was the angle of the neck in relation to the plane view, which is ever-so-slightly off. This isn't really an issue, however, as I have to carve down the receptacle for the neck overhang anyway. I will just keep in mind that I have to fine-tune the level on either side of the mortise and tenon.

But, hey!, it's starting to look like a guitar!

Neck Block Fitting

The tenon and heel on the neck had yet to be cut at the correct height and angle. As mentioned before, I'm going for a 3.5 degree angle for the neck. I achieved this by making a very simple jig. All I did was glue a piece of wood edgewise onto another piece of wood at 3.5 degrees (lengthwise - the wood had to be perpendicular to the base) to the straight edge. With the fingerboard held firmly against the 3.5 degree board, I ran it through the table saw, after I determined the width of the tenon and heel (based on how thick the guitar will be, etc).

The image isn't plainly obvious - the piece of wood in the upper left of the top photo is the 3.5 degree angle against which the fingerboard was held. What you can't see is the edge of the base that was straight against the table saw fence. Anyway, you can see in the second photo the result, as the tenon and heel are now the correct depth and angle (though the photo seems to exaggerate the 3.5 degrees somewhat. Dang parallax!).

Oh, in case you're wondering, the grey blob on the neck is where I used epoxy to blend the curve of the added overhang with the sides of the neck at the join. It will be painted black, so this will not be visible... nor will the scorch marks from cutting the wood be visible.

Preparing The Neck Join

Wow, three posts in one day - I didn't actually do all this stuff today, I just got around to posting about it.

In this photo you can see the notch I cut in the guitar top for the mortise, and you can see the pencil line around that which indicates where the fingerboard overhang will extend to. There is a little extra wood still on the top at the outer edge of the neck join area (where the cutaway is). That will be gone when it's trimmed to fit the side walls after they're done.

Anyway, the long tenon on the heel of the neck will need to fit into a long mortise in the neck block, which means I need to access the mortise via the top of the guitar (not all mortise and tenon joins are done this way on guitars, but archtops often are - many acoustics are built with a very shallow mortise and tenon, only accessed from the wall behind the neck join).
The neck will sit at a 3.5 degree angle from the body of the guitar. It will also have to be set slightly down into the top so that only a portion of the overhang and fingerboard will be higher than the guitar top at the 14th fret (the 14th fret is where the neck will meet the body). The reason for this position is to allow for proper string clearance with a 1" bridge. My plan is to make the neck block square-cornered, but carve down the guitar top area that will sit under the finger board overhang (the area within the pencil lines), at an angle, until the desired depth and neck angle are achieved.

Strutting My Stuff

Yeah, yeah, I know. My puns are a little lame, and more than a little silly, but I have a seven-year-old daughter, so silly puns are part of my daily communication skills.

So... I carved and glued the struts in the guitar top. Sorry I missed getting pics of the process. Essentially, all I did was to take two strips of spruce (the same spruce I used for the top) and orient them so they were also quarter sawn (the grain edges going up and down, rather than side to side). I used a pencil to follow the curve of the inside of the guitar top on the struts, with them positioned where I wanted them, and then cut them on the band saw.
Using a variety of tools - from tiny planes to sandpaper to an X-Acto knife - I gradually refined the bottom curves until they fit perfectly along the contour of the carved surface. They are spaced so that the outer edges of the struts match where the outer edges of the neck and tail blocks will be.
They are now glued in place. I will do the final shaping with my tiny luthier planes, as you can see they don't quite match exactly, particularly at the bottom end.

Head Stock Re-facing

I re-faced the head stock on the neck. You can see below (meaning, the previous post) that it had been a rather unattractive brown mess (it was originally painted black, but I sanded it off hoping it would look nice underneath... no luck). The new face is a thin veneer of curly maple (1/42" thick). This will be same veneer I use on the sides of guitar body.

I started by cutting a piece just slightly larger than the head stock and glued it on, using a flat block of wood and some clamps to ensure that it was pressed tight and flat against the face. After the glue dried I just trimmed the excess wood with an X-Acto knife and sanded it smooth around the edges.
Next came the holes for the tuning gears. I carefully drilled through the existing holes from behind and trimmed out the excess, again with the X-Acto. I then used a cone-shaped grinder from my Dremel kit and cleaned up the circles by hand (no power needed here, one might slip and make a huge mess). And viola! nice round tuning gear holes in the veneer to match the ones that were there to begin with. This is much easier and much more accurate than trying to cut the exact shape and the holes before gluing it up. The only issue that MIGHT be a problem is if you mess up your veneer while working on it, it's already glued on. I guess that's why they tell you to be careful.
The truss rod access notch needs a tad more cleaning up. I'm not too worried about the edges of the veneer beneath showing through, as this area will be hidden by the truss rod cover, which will be made of ebony.

Neck compromise.

Well, for a number of reasons, the neck I'm building is ending up going slower than I had hoped, so I decided I would use a pre-made neck. It was rescued from an acoustic, and I modified the bottom end to have the overhang. I didn't get much in way of pictures, but essentially what I did was remove the old fingerboard from the existing neck (very careful prying - very anxious was I), and take out the truss rod. It had been oriented with the adjustment at the bottom end, so you could work with it from the sound hole on the acoustic. In my case, I want the adjustment at the top end, to be hidden under a truss rod cover. Obviously, my guitar won't have a convenient sound hole down at the bottom end of the board.

I had to extend the cut for the truss rod out beyond the nut region. I looks a bit of a mess right now, but that will clean up and get repainted. After some effort to ensure that the gluing surface was flat and true, I got my courage up and splashed on the glue. In this case, I didn't use the waterproof Titebond I had been using for other parts, mainly because it's quite possible the fingerboard will need to be removed at some point or other.

I wanted the head stock to be "my own", so I re-cut the top end into a new shape. It isn't the shape I originally designed, because it wasn't wide enough.

Quick Update

Life is getting in the way of having this project done in a reasonable amount of time - working out of town a lot, and various other factors, are limiting what I can get done on the guitar. I don't want to rush it either, as this will almost certainly lead to an unusable instrument. In the interest of moving things along a little faster I am considering using an existing guitar neck I have on hand. Although it isn't from an archtop, I can easily modify it to do the job. The best part is that it has its own truss rod that I can reuse, and the channel is already there. All I need to do really is add the extension for the overhang at the bottom end, and put my own fingerboard on.

The neck I have started will be made good use of for another project. If this guitar works out I plan to make another like it.