Trust Rod Fitting

Now is the time to fit the truss rod (or trust rod, which I feel is more apt, as I am really hoping it is going to work!). The aluminium anchor piece needs to sit under the fboard near the headstock. A hole was chiselled out for it carefully. I have to remember that the neck will be shaped later, and that getting carried away with chiselling could result in a weak end, which is the sort of thing to be avoided at all costs.

The anchor piece slots in OK.

The same sort of thing was done for the adjustment end. This one had to be done even more carefully as it will be visible after the fboard is stuck on. A couple of 30mm screws hold in the nylon bearing block. This had to be penned black as it too will be just about visible. The trust rod was covered with some 6mm heatshrink sleeving and a little oil before it was commited into the chamber of doom, er, the truss rod channel.

Everything was checked & double checked and then it was time to fit the wooden fillet that has a curve that matches that of the (chamber of doom) channel. Lots of glue and clamps as per usual.

Put to one side and allow to dry - and here's one I made earlier. Aaah a Blue Peter dream sequence!

When the glue had dried, I cautiously wound up the tension, looking for a bit of backwards curving. Disaster! As I wound the tension up, the neck started to show a small amount of forwards bow, ie in the same way that would be caused by a set of strings.

Smeg!

Due to the amount of tension I put on the neck, the anchor piece had also started to migrate south for the winter. Whilst I puzzled over what seemed to be a loophole in the laws of physics, I thought I had better strengthen the anchor piece to neck connection with some additional blocks of wenge. This meant losing a small amount of the channel intended for the carbon stiffening rods, but this was more essential. Some M5 washers were also 'drifted' into place just to help out.

Well, here's my theory. Ahem.

The neck currently is not shaped, it has a rectangular cross section. Because of the amount of channels cut into the top, the absence of the fboard and the extra thickness and girth of the neck it is not only much stiffer than a standard neck, but the stiffness is predominantly underneath the trust rod. When the rod is tensioned, although the curved channel should cause a backbow, at the present time with the greatly increased rigidity of the material under the rod, the top of the neck is more likely to be compressed causing a forwards bow.

This seems to make sense, but I cannot do much about proving it until the neck is a lot closer to being finished (ie back coarsely shaped, fboard stuck on). This is another reason why we all have to Trust In Rod.

Go Naked

Looking at the size of the veroboard layout for the MoonBassAlpha animation circuitry and then looking at all the cutouts that I have made in the body, I soon realised that there was nowhere for the electronics to live. A PCB needed to be knocked up to keep the size as small as was practical. The board was designed using CADStar, which is too powerful for its own good and will let you to make quite fundamental errors if you wish. I finished the board off with my customary "its close enough for jazz" air of carefulness...

I was tipped off about a local PCB manufacturing company Spirit Circuits who offer a cracking free PCB service! I am sure it is for legitimate prototype work where they hope to get repeat business rather than homers, but I'll just have to placate them over the coming months. The idea is that they supply a one-off board with the copper tracks and drilled holes, but without any silkscreen legends or solder resist mask. This is why they call it "Go Naked".




The finished board looks a bit lost in their A4 paper sized panel. Once it is cut out then construction can begin. The smaller parts are placed first and it soon becomes apparent that fine surface mount parts on a board with a ground plane really does need solder resist. It is quite tricky to avoid shorting things out with only a 10thou gap.



After the small stuff, the meter was brought out to verify that there were no short circuits and then the larger parts were slapped on. I mananged to incorporate a few cock-ups into the board design (no surprise there) which required one or two upside-down components and a couple of after-thoughts tacked on in precarious places.

The board was ready to try out and I needed to see how noisy it was going to be. Very few guitars have animated fboards, and probably even fewer have switch-mode power converters to power them. The lights take around 100mA from a 5V supply and running this from a 9V battery would make it a rather short-lived affair. Much higher capacity can be found from AA rechargeable batteries, so the MAX856 converter takes this 2.4V and changes it to either 5V or 3.3V (which gives a neat choice of brightness levels).




After a few more modifications, the board is not putting out too much noise. It needs to be kept away from the pick-ups as far as possible, (distance helps) and 3V3 operation is much quieter than 5V. All-in-all the amount of buzzing and whistling that makes it to the pick-ups is pretty small, and won't be noticed when everyone's playing. For recording use, I could just turn the lights off...


The Trust Rod Ends

At last the rod ends have been finished. Many Thanks to Keith at Eaton for knocking the brass adjuster up in his, er, lunchhour. This really looks good and will be seen somewhere at the end of the fboard once I channel out a place for it to fit into. It is going to run in a nylon block. This should spread some of the compressive force back into the wood and turn more smoothly than just a manky old washer alone.

The thread gets a bit tight in the middle - possibly it was tapped from both sides and didn't meet exactly, so I need to drill part of the thread out from the large end. It will still have a good 12mm of thread remaining.

The adjuster is based on the ones used in the Ernie Ball MusicMan range of basses. This seemed a much more elegant way of adjusting the rod instead of trying to find a hex-key down a tunnel like most guitars. I couldn't find one off-the-shelf at the time though I am sure somebody makes them somewhere.



The other end of the rod has got to be anchored into place (somewhere under the first fret or thereabouts) with this interesting shaped piece of aluminium fashioned by me using the milling machine at work. Hmm - functional, but it is probably just as well it won't be on display.



I hope all this fits...

Shaping The Body With Chiselled Features

The plan view of the guitar was as far as I had really got with my full sized sketches - I am not known for possessing any great depth. To carry on the fish pretzel theme that I started on the headstock, I want the body wood to look a bit organic, to flow and overlap rather than just sit there and look heavy and cumbersome. So this requires a fair bit of wood removal to make it happen.




At first the router was used. This is great for removing material, but in this case is self-defeating. After a while, all the flat surfaces that the router needs to sit on have been buzzed away, leaving a choice of it sitting on precarious 'islands' of the original height, or freeform use. Hmm, sounds like a trip to A+E is only seconds away if I try that too often, so it is back to the manual methods after this brief flirtation with power tools.




Chisel! The word sounds a misleading - like a chisel is used to stab at the wood and rip a bit out. With a decent (and sharp) chisel the ash can be worked with a bit of effort. Ash has a large grain pattern and it seems to change from quite easily workable in some parts and really hard in others. This takes some getting used to, but understanding this helps to work with the wood and not against it. I had to keep sharpening the chisel on an oilstone throughout the shaping.





Between major bouts of chiselage (what a good word - I wonder if it exists?) sanding the contours with a block helps to blend the shaping into pleasant curves.

There are a few places on the body, inside the teardrop shaped cutouts, where it is difficult to work on. This could be why nobody else makes a guitar body that looks like this?




Here's the body parts pushed back onto the neck. All the shaping and radiusing apart from the the initial rough router work has all been done by hand (and aren't those hands feeling sore!). The top has been shaped so that my forearm will have a nice resting spot. From the front the central walnut stripe is just about visible.

The truss rod channel and positions for the fboard lights are just visible further up the neck, at 3rd and 12th fret positions.

It isn't easy to see in the photo, but there is still a way to go. The body is still proud of the neck in places, and the bottom of the guitar needs to end in a curve (the neck is just sawn at an angle at the moment).

The next step is to think about where I place two volume pots, a 4-pole pickup selector switch, the 1/4" jack socket, the pacman leds on/off switch & select button, the pacman led circuit board and the batteries. No problem, I'll put it all in one of the holes...