HKG-SEC: Necking and Getting Wood

We come now to the heart of the matter, the meat of the thing: the neck for this guitar.

I needed raw materials: a truss rod, a fretboard, and a neck blank.

Thanks to Warmoth and Stewart McDonald, I got them.

SEC template (top), Warmoth angled headstock neck blank (center), Stew Mac 12″radius rosewood fretboard (bottom)

I ordered a truss rod from Stewart McDonald too:

As I have already shown, there are several factors/problems that are interrelated in building this neck.

Three measurements/dimensions are important, and two of them are critical.

The least important is scale length; making sure the distance from the bridge to the nut is (in this case) 25.5 inches. This is not an absolute measurement, because bridges can be adjusted to make intonation more accurate.

This means I have to be sure to be very careful with the placement of the neck and fretboard, because this guitar will have an angled headstock.

Straight headstock (top), angled headstock (bottom)

For this particular guitar, the Floyd Rose nut should fit flush to the ‘break point’ in the neck. It has to be completely on the flat surface or it won’t work properly.

So that end of the neck is not negotiable.  But it also means that the bridge end of the neck must be cut in exactly the right place.

I looked for photos that might help me understand and verify the placement of the fretboard on the neck. Luckily, I found some.

This photo shows the 22nd fret placement. That’s a very helpful piece of information.

I checked and re-checked and checked again, and eventually I decided where it would go: 

The second critical measurement (that in the case of the SEC is tied to the third) is the centerline of the neck.

If your neck is off center, it’s useless. At best, the strings won’t line up properly and the guitar won’t stay in tune. In the worst case (or with the SEC), you won’t even be able to put the neck on the guitar!

The third measurement or specification is the 4″ SEC radius. The radius is the easy part. The hard part is making sure the radius’s relation to the centerline is correct. That’s crucial.

When I made the SEC template, I managed to create an exact negative of the SEC cutout for this guitar. What I mean is that I shaped the template so that it fit the cutout and gave me the shape I would need for the neck.

But I had a small problem. The template fit perfectly, and the centerline was straight from the bridge to the nut end. However, it was a little under 1/16th of an inch low.

In the above photo, the line seems further out than it really is because the photo is not perfectly level. Just look at the left end to get an idea of the error.

But this is actually an easy thing to overcome.

It’s also why I used a template first, because if I used the neck blank, I’d be stuck with a useless piece of junk wood.

I drew a centerline onto the neck blank taking two things into account.

One, it needed to be square to the break point at the nut end. That’s easy enough to do, since Warmoth’s neck blanks are milled square anyway. Not a headache.

Two, I needed to draw the centerline lower than usual (not centered on the neck blank) because of the ‘shark fin’ sticking up out of the top. At the same time, I couldn’t put it too low because I needed at least 2 3/16″ at the bridge end and I needed to make sure there was enough space at the headstock end for the headstock.

That consideration was made easier by the headstock template I had made.

This was an image I downloaded. I glued it to a piece of MDF and cut it close to the line with a jigsaw. Then I used sanding drums to smooth out the cuts up to the line:

It’s one of the reasons I made it!

But its for a standard, non-reversed headstock. No problem; I just transferred the centerline down the two edges and then joined those two points on the back.

I drew the center line on the neck blank after checking the headstock placement. I also tweaked the design of the headstock a little, making the middle (straight) section a little bigger.

You can see it in the photo below.  You can also see how the center line is off-center on the blank.

I then drew the lines for the edges of the neck, from 1 3/4″ at the nut to 2 3/16″ at the bridge. I may have used millimeters, I don’t remember.

Since the SEC ‘fin’ was wider than the neck blank, I needed to cut a piece out of the unused portion of the blank up by the nut. I then glued that piece down near the bottom of the blank:

Once the glue was dry, I cut out the SEC curve and began carefully sanding it on the disk sander, taking my time and constantly checking both the fit and alignment. This was really the critical point of the build. Luckily for me (or because I had done my homework and worked both diligently and intelligently), the neck ended up fitting really well and, more importantly, being centered properly.

At this point I needed to rout the channel for the truss rod, which is designed to counteract the force of the strings pulling on the neck. These Hot Rod truss rods from Stewart McDonald use a special router bit for cutting the channel. I use a special jig that I made from plexiglas to rout the channel in a straight line:

This particular truss rod would stick out the butt end of the neck, so I placed the jig accordingly. A few passes with the laminate router, and we’ve got a truss rod:

It was now time to shape the neck. I had made a template from a shelf. It tapered from 1 3/4″ to 2 3/16″ (or so I thought) with straight edges. By clamping it on top of the neck blank, I could use it to get very straight, very clean edges on the neck blank.

I also took the opportunity to reduce the thickness of the ‘fin.’ You can see in the above photo that it’s had some wood removed.

I did that   because the neck sits ‘proud’ of   (higher than)  the body. Here’s an example on an N4:

But this N4 uses a squared  inside corner, and I wanted to try and emulate the earlier Davies design:

That gentle curve is structurally unimportant, but it looks nice and is not that hard to do. Using a bullnose router bit and a collet was the easiest way to accomplish it.

I checked the offset of the bit from the collet (around 1/16″). I clamped the template I used to shape the neck 1/16″ away from the line where the fretboard would end. That means the bit would cut to the line:

I cleaned up the machined area with a little sandpaper and it was finished.

Up next: Fretting.