Making Light Work

Whilst the circuit boards were being manufactured far away, I have been able to spend time getting the neck ready. The old frets were pulled out and the f-board was planed until the lighter coloured maple could be seen. As the shavings of faux-rosewood fell away, the truss rod assembly also became visible. The truss rod is the type that has a U-shaped extrusion so there is a 10mm wide piece of conductive metal running just under the place where the PCBs will sit. A (thin) layer of insulation will be required here to avoid any short circuits.

A pair of 4mm carbon fibre square rods were glued at the edges of the planed neck surface. This should replace a little of the strength that the f-board was previously supplying and forms the sides of the LED PCB tunnel. This was glued with two-part epoxy resin and clamped to keep flat and the correct distance apart.










The PCBs arrived and thus began the tedious process of soldering 400 decoupling capacitors followed by 400 LEDs. This took a few dedicated days and evenings with some timeout to buzz out each board for build errors. The LEDs look eye wateringly bright to me!

The boards were tested (and a few dodgy joints repaired) before they were offered up to the neck. The head PCB is joined to the next five strip PCBs by short lengths of solid core Kynar wire. This daisy-chaining approach is taken to electrically connect all the boards together.












Small offcuts of 0.5mm x 3mm carbon fibre flat bar were attached with double sided tape to keep the spacing of the strip boards consistent and were placed between capacitors. Lastly a good quality 15way D plug was fixed to the neck and wired to the last five strip PCBs.




















The f-board

5mm dark tinted perspex was chosen for the new f-board. It is dark enough so that when the LEDs are off, it looks quite normal (but very black and shiny). When the LEDs are on, they are bright enough even through the dark tint. I could only find the 5mm thick perspex in a 500 x 500mm size which at first glance seems too small for a 630mm f-board, but there's always a way...

Before the f-board is attached to the rest of the neck, it makes sense to cut the fret slots whilst it is nice and flat. An attachment for a Dremel I concocted in the past has been improved by adding a rotary encoder, motor, leadscrew and Inphase / Quadrature digital readout. This allows me to precisely (well within +/-0.2mm over 600mm) navigate along the length of the work-piece before making a transverse Dremel circular saw cut. With my table-of-fret-positions all freshly worked out on a spreadsheet it was childs play (ie noisy and messy) to zip through. The slots were checked against a handy Westfield bass and looked pretty good.

The rough cut f-board resembled a stripey tie. After a bit of trial and error, it seems that ordinary two part epoxy resin isn't very good at sticking perspex to carbon fibre, so an acrylic based adhesive (I should have known!) was required. I eventually found some Voodoo glue that claimed to do the trick and also cured to a black colour to blend in. This was also a two part system, but had a working time of just a few minutes so it took some careful planning of the sequence of events to get the glue mixed, spread on the top of both 4mm carbon fibre neck rods carefully to avoid to much squeeze-out followed by placing the perspex on top once and not moving it around.

After the clamps were released, it didn't fall apart which is success in my book!

24 hours later, the LED assembly was carefully slid into place and connected to the test board for the first glimpse of how it will look!

The f-board edges were trimmed to remove excess material and then the nice shiny surface had to be destroyed by the profiling process. This time around, I purchased a 12" radius wooden block which looked a bit like a school blackboard rubber to me. Coarse 80 grit sandpaper was used to remove the bulk before going through the grades to 2500 grit.

This was followed by T-cut and car polish to return the surface of the f-board to (nearly) its original splendour.


Fretting

Fitting frets into a wooden f-board is a nice affair that involves tapping lightly with soft faced hammer so that the wood gently eases out of the way leaving a superb result. Not so with nasty perspex - especially one with no real visible means of support under most of it. One clout with a hammer and it could easily crack resulting in several weeks of work being wasted and blood pressure reaching new and exciting levels...

After initial checking, the interference fit of the frets would be too risky, so the fret slots had to be widened carefully with a handsaw until they could be pushed in by hand. This is where the term 'kerf' became part of my dictionary! The frets then had to be glued in to prevent them from falling out or moving around. These additional steps did occasionally have a bad effect on the beautiful surface finish of the f-board, but there's no use crying over spilt sodium...

The frets were levelled and dressed as normal, the neck ends trimmed and the finished article looks quite decent to me.

Next are circuit boards that control the LEDs and the pickup active tone buffering!