Wednesday 26 April 2017

Fixing the light-up guitar neck

One of the great things about having moved into the workshop bungalow is that I can try out ideas quickly and easily and designing through repetition is a doddle. In the past, I'd have to plan what I wanted to do/make then visit the unit, make it, bring it home and just hope it worked - at least until I could get to the unit a second time.

Now I can design something and whizz it out on the laser in minutes, not days. So when I got the RGB LEDs soldered up for Keith's guitar, I could play about with a few designs for sticking the fingerboard to the guitar neck.

If a design didn't quite work or fit properly, it took just moments to knock out another, amended version. It took maybe three or four goes to make some mdf standoffs to fit around the LEDs on the reverse side of the fingerboard

Because I'd positioned the LEDs by hand, rather than using a template or a PCB (where the position/location of the LEDs is fixed) they didn't exactly line up with the drawing I made the mdf template from. But it only took a bit of fiddling about to get a working fit.

Next we used some epoxy glue to fix one side of the mdf to the fingerboard, and clamped it down to a board to get the fingerboard as flat as possible.

Although not fully cured after a few hours, the glue had set enough to allow us to move the fingerboard and glue it to the guitar neck.

Now it's just a case of leaving overnight and see how things look in the morning! We used epoxy rather than PVA since many of the luthiers recommend it for it's stability. Apparently PVA can shrink over time, which might cause the fingerboard to pull or bow. Epoxy doesn't suffer from this (although "proper" luthiers recommend against epoxy as it makes a future repair almost impossible - if this thing goes wrong, the entire fingerboard will need to be sanded off!)

And there we have it - a light-up guitar neck, ready to be fit to the rest of the instrument. Because of the additional 2mm height added under the fingerboard, we're going to have to raise our bridge by the same amount (otherwise the strings will buzz as they "fret out" on the higher frets). A simple shim under the bridge raises it by 2mm, but this also means we're going to have to screw it down hard, losing the tremelo operation (having a moving trem might distort the shim under the bridge over time). Luckily the pickups can be adjusted by more than 2mm, so we've simply raised the nut, strings, bridge and pickups all by 2mm and the playability shouldn't be affected.

We'll have to assemble the rest of the guitar for testing.......

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