Truly headless

After postponing it a number of times, I cut off the strat headstock of my very fine Warmoth neck. That took a bit of self persuation, but I needed it headless. A brass angle bracket is holding the strings. I also made a new acrylic body. This time, I tried to make it really fit my torso. I tried too hard: Most of the curves and shapes are too pronounced and it's actually too tight on the body.

Bridge and tuners are the same as in last post. I plan to make an improved version of the tuner bracket (or perhaps abandon it in favour of one using my plunger type tuners).

The pickup is a P90 mounted above the strings. I plan on experimenting with a couple of experimental pickups using primary coils with few windings and a current transformer, but I haven't gotten around to that.

It still needs a strap to be really comfortable.

Things I might do next:

• Make a steam bent plywood body in the style of the acrylic ones.
• Make a new and more ergonomic acrylic body.
  
• Make a proper wooden body for the neck and ditch the rectangular steel tube for a while.
• Test and develop my pickups.
• Get back and properly finish the two-string bass. This involves adding a slidable pickup and a piezo-pickup with preamp.

Future project

Here's an instrument which I'd like to make some day:

• Three string blues slide guitar
• For playing seated
• Sliding nut
• No strap
• Spine: 30 X 12 mm aluminium rectangular beam - freely vibrating
  
• Piezo pickup on aluminium beam
• Sliding pickup under strings- probably an ultra flat one with few primary windings and a current transformer.
• Plunger tuners (this principle)
• Minimalistic ergonomic body - the first version would probably be made from heat-bent acrylic plate

New tuner design

In the previous post, I described my intention of creating a playable testbed for experiments with different pickups. It turned out to be nice to play, so I improved it with a strap horn and the acrylic body from my t-beam bass. As it turned out, it was quite neck heavy. And since I prefer a headless guitar in most circumstances, I began to consider a tuner system down behind the bridge plus removing the headstock.

The design - as many others - uses traditional tuners mounted at the end of the guitar. Most of the existing designs however, has the strings fan out from the bridge and onto the tuners. The tuners have a lot of distance between them in order to allow room for the fingers when tuning. One solution is a design using two rows of three tunes facing each other and sharing the same slot. For the latter, I bought a set of six twelve-string tuners (they have the pegs closer together than six string tuners, saving space).

I built a bracket for mounting them on the end of the testbed guitar. It is soldered together from rectangular brass profiles. The profiles carrying the tuners are at an angle so that there's a (reasonably) straight string pull.

The tuners are made from one side of the twelve string tuners, cut in half - i.e. 2 x 3 tuners. I found out that they had a nice copper coating beneath the crome, so I filed away some of the chrome. I hope, when the steel and copper oxidizes, that they will look more discreet. They seem to work decently, but I imagine that better quality tuners might improve the system somewhat.

The strings can be tuned easily and precisely. Mounting the strings is a bit troublesome, but will probably be easier when I've tried it a couple of times. Unfortunately, my soldering job was insufficient and the top plate broke off. When I re-soldered it (and bolted it too, to be on the safe side), I was too hasty, and the holes for the pegs didn't line up. I had to do a bit of filing, and now the arrangement works, but less smoothly than the first time. I'm not completely satisfied, so I will buy a machine vise for my drill press and make a better bracket. That will give me a chance also to try some better tuners. They could be these due to their good looks (though it might look too _deliberately aged_ for my taste) or these due to their high gear ratio

If they keep working well, I'll cut the headstock off the neck, but for now I am anchoring the ball end of the strings in the existing tuner pegs on the headstock. I plan to play it for some time and make sure that it's a keeper (the overall design, not this particular version). I've got to be certain this works before chopping away.

A body that preserves vibration

With the addition of a body to the T-beam bass, it begins to resemble an instrument.

The body is a 3 mm (around 1/8") acrylic (or plexiglass) shield, cut with a saw and an angle grinder, polished, and bent in shape with a hot air gun. As with almost everything else on the bass, it is not intended as the final version. For this, I will use thicker (probably 5 mm) acrylic sheet and have the leg rest further to the back.

The acrylic shield is slightly bowl-shaped so it follows the contours of my body. It's a fairly deep bowl shape ;-) It has a leg rest bent into the lower part and an arm rest created by folding back a wing on the upper part. It quite looks like the body of an Ovation Breadwinner, though that was not the intention originally. It's very comfortable, and I expect it to be even more so when I've moved back the leg rest.

The four mounting supports that connect the shield to the stick will have to be replaced with a central support mounted on one of the two places where the stick has least vibration. A so-called node. I located the node by suspending the stick on two springy foam blocks, pouring salt on the stick and tapping it with a knife handle. As predicted in the marimba literature, the salt would gather to show the location of the node. Luckily, the node is somewhere in between the mounting supports, which makes construction easy. BTW; marimba and vibraphone builders do a lot of interesting research into the acoustics and vibration of wood; something that the guitar builders might draw upon in their work.

The reason for having the shield mounts on the node is to preserve vibration in the stick and not have it travel through the body and into the all-absorbing torso of the player. The node does not vibrate - or at least it vibrates less than other areas of the stick, meaning that less vibrations will be transferred from this point to the shield than from any other areas. I expect it to have a pronounced effect on sustain, and perhaps also on tone.

Some sort of leaf spring suspension mount might give even better isolation between the shield and the stick, but that will have to wait for a later version.

Guitar Ergonomics

The classical Guitar

Back in the old days, before we had electric guitars, a guitar looked like this:


CC Martin Möller, Creative Commons Attribution ShareAlike 2.0 Germany, resized by me

It's beautiful and sounds nice, but it's not particularly easy to play.

There probably exists a number of very good reasons for this unhandy shape and size. Being totally acoustic, the guitar needed to have a large body. The tuners had to be at the end of the neck, as mounting them on the thin and acustically crucial soundboard would probably have been out of the question. Why the body had to have the shape of a rather large figure eight is beyond me. It probably has to do with acoustics, too. Alternatively, the reason mighe be that it makes it easier to rest the guitar on your thigh - and for symmetry reasons, the other half was shaped accordingly.

When technologies evolve, they often retain some of the drawbacks of earlier versions. Probably because many designers (and customers) are quite conservative and don't like things to depart too much from what already exists. Early automobiles, for example, resembled horse carriages to an unnecessary degree.

The Electric Guitar

I think the same effect is in play for the electric solidbody guitar. At least when looking at the most well-known brands and models such as Fender, Gibson and PRS. It still has a head at the end of the neck, even though it tends to make the guitar neck heavy and always hits other objects and people when you move the guitar around. It still has a rather large and thick body, though acoustics do not come into play any longer. It still has the shape of a fat figure eight, albeit with cutouts at one or both sides for easier access to the higher frets.

To me, the bottom cavity of the figure eight is in the wrong position: If i have it on my right thigh, it feels too much to the right and vice versa. A cavity located nearer the bridge would be more suitable, as resting the guitar on the right thigh would give a usable position. At least, so I think. Regarding the other inherited features from the classical guitar, I'd like a thin guitar allowing my playing action to be close to the body, a compact guitar with no head for knocking out the teeth of other band members, a light guitar that don't break my back.

The Ergonomic Guitar

Hence, one of the early decisions in the desigh of the T-beam prototype was to go for a headless and ergonomic design. On Building the Ergonomic Guitar, there is a lot of discussion on suitable shapes and design principles, plus articles on some of the smaller luthiers, who build ergonomic guitars. Especially the Klein guitar shape caught my attention: It simply looked like it would be easy and relaxing to play.


My design will be something like this. The exact shape of the wings may vary. I might experiment with several shapes and woods for the wings. But overall, this is what it will look like. I don't try to make it look like any particular one among the existing ergonomic guitars, but I think the Forshage electric guitar is the one it's going to resemble the most. The Forshage, in turn, is inspired by the Klein, BTW.

The picture of the ergonomic T-beam guitar is an older (i.e. around two months) design. I later abandoned having the traditional tuners at the bottom of the guitar in favour of a different desing, instead using a bridge with integrated fine tuners. More about these considerations in a later post.