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Routing Continued

My stuff finally arrived from Guitar Fetish, what this means is that I can move on with drilling the holes for mounting the bridge and the pickups. The most important part of the instrument is the bridge in relation to the neck. My neck has a scale length of 24.75″. The scale length is the distance between the nut at the top of the neck and the bridge on the body. Tension is created between these two points and it is the vibration of this particular section of the strings that makes the musical notes. Now the distance of the bridge could be any distance from the nut and you could tune the guitar to the open string tunings, say EADGBE. However in order for the notes on the frets to also be the corect pitch (this is known as intonation), the bridge must be placed at the correct distance from the neck nut, 24.75″. The pitch a string makes is a function of the distance of the vibrating portion of the string and the tension of that part of the string. There is a specific mathmatical formular which determines where the frets must go, spaced in decreasing intervals in order to make the correct notes. If the bridge is the wrong distance, each fret will get progressively further away from the correct pitch making the guitar essentially useless unless you are into some form of microtone jazz. So no pressure to get this part right then…

The bridge is attached to make sure it is in the right position.

I attached some of the tuning machines to the neck to string the outer strings to the neck and through the bridge, this way I could line up the bridge with the measured scale length, I also could see where the outer strings would lie. It wouldn’t be much good if one of them was to lie off of the fretboard. After all the testing I marked the spots where drilling was required and attached the bridge with the strings on to test it out. This was the biggest moment so far in the entire build. And find out how I went after these commercials… no just kidding, it worked great, the string action was good and the intonation was as close as you could hope for without fine tuning it later with the adjustable parts of the bridge. Success!

With that sorted it was time to move on to routing the holes for the pickups. The location of these mounting parts aren’t random either. The importance here though is in the overall sound of the guitar, not it’s playability. It’s generally accepted that the best place to place pickups is where there would be a fret divisible by 12, or to put it another way on an octave. This is because the octave represents a point where there are the most harmonics. A vibrating strings doesn’t just create a single frequency but a multitude of related overtones along side the dominant frequency and the octave points have the most overtones. Placing your pickups under these points therefore produces the most harmonically rich sound. Another consideration is the distance to the nut, the closer to the nut the pickup is located the “warmer” or bassier the sound is, further away from the nut the sound becomes “crisper” or treblier.

Neck pickups are nearly always placed under the place where the 24th fret would be, unless there are 24 frets on the fretboard in which case the pickup is placed as close as possible to the 24th fret point. The bridge pickup however is not always placed directly under the 36th fret and may be placed a little closer or further away from the bridge nut depending on your preference for a warmer or crisper sound. I used my other 24.75″ guitars as a reference point for the bridge pickup because I like the sound they produce so I just copied thier positioning. I won’t know what the guitar sounds like through the pickups untill the guitar is finished because wiring up the pickups is the last step before actually stringing up the guitar.

The guitar after pickup routing.

In routing the pickup holes I wasn’t as meticulous as I had to be for the neck pocket, the reason for this is that the holes will be covered by plastic pickup mounts which will cover the hole. It doesn’t need to look great, and functionally I needed a minimum hole size, so I drew an inner and outer line on the guitar and routed between these two lines, the results don’t look amazing but they got the done in a timely manner. What isn’t shown here is the rout for the guitar controlls. My router couldn’t rout deep enough to allow the controls to be threaded trough the body so I routed all the way through. What this means is that I will have to create a front control plate for the controls to thread through which secures them to the top of the body. Something like this… but using a black 3-ply plastic.

An example of the front control plate.

I also made my permenant neck rout fix today and glued it to the neck pocket. I used a piece of the left over pine, cut it to a smaller depth and then used my orbital sander to sculpt it into the shape that I want. I feel much better about a solid piece of wood supporting the neck angle, it will look better too.

Here you can see the results of the neck fix.

The next step in the process is probably the main reason you build your own guitar, the individual look and this is called the finishing process. It involves sanding the bare wood, filling in the pores, applying stain, colour and finally clear coats on top to protect the whole thing. I must say, preparing for this stage has caused me the most stress because sourcing the materials I need hasn’t been easy, but hopefully by sharing my findings it may be less stressful for people reading this who may want to do a build of their own.

 

 


The Neck Rout

With the basic body shape complete it became time to do the neck rout. Neither me or Dad had ever used a router before so we had to teach our selves. With a bit of experimentation and testing on a scrap piece of wood we made a replica of the rout that turned out well. Normally a router will use a jig, a replica of the shape to be routed. We didn’t make one of these but instead used dimensions of the router, such as the distance between the edge of the machine and the start of the rout, it was quite effective and produced the shape we want.

We practiced on a piece of scrap first.

Let’s talk about why the neck routing in particular is so important. The short verion is that it’s all about geometry. The angle between the nut at the top of the neck and the bridge (the two points between which tension will be created) has to suit the type of guitar that you are building. This picture from the Tundra Workshop website demonstrates quite well what I mean.

This image shows the importance of neck angle.

My guitar has a flat top, but the bridge doesn’t sit flat to the body, it’s an adjustable height type that sits a little way off the body at a minimum and so a flat neck angle would produce an uncomfortable action height, the height of the stings away from the fret board. Playing a guitar like that would not be easy, or fun. So I need an angled neck, luckily the neck I scavenged from the cheap Les Paul copy is angled at the end, but when we tested it on the practice neck rout it wasn’t quite enough, so that means the neck rout would also have to be angled. This isn’t an easy task.

This images shows our off the cuff jig method.

It turns out that when we adjusted the router to do the proper neck pocket, it was a bit too deep, making the neck sit too close to the body. Obviously once you make a cut too big there is no going back. So what we have done is to use thin pieces of wood to prop up the neck, this doesn’t produce as stable a neck joint as a solid piece of wood, I have plans to use a small piece of the left over pine and then sculpt it to the correct neck angle to add a more stable permenant height and angle corection. For now we used thin pieces of fiber board.

The fibreboard used to pack the neck is a temporary replacement.

Those pieces you see either side of the neck pocket will be cut to create a completely flat extension for the neck to bolt on to. If they were left there the neck joint would be a little bit more stable, but it is harder to play with extra wood in the way of the fret board, so it has to go. Attaching the neck to the body was a bit of a drama. The neck having already been bolted on to a previous guitar already had holes where it attached. Trying to line up with these hole on the back on the neck pocket proved almost impossible, so we packed the previous holes with wood and created new screw holes using the screw plate as a template from the back of the neck. With the neck attached it’s really starting to look like a guitar.

With the neck attached it’s starting to look quite good!

At this point I have to wait for my order to arrive from Guitar Fetish as that’s where I ordered my bridge from. I can’t drill the hole for the bridge or decide on the placement of the pickups untill I have those things in hand, so I will talk more about bridge placement, pickup placement, and pickup choice in later installments.