24mm x 21mm x 74mm
The heel of the neck is shaped with a chisel and Japanese saw rasp.
Meanwhile the fret slots are cut. The fretboard was made 8.5mm thick rather than the usual 6mm to acomodate the sympathetic strings. Thus extra care and attention was needed setting up the fret slotting jig.
Tapering the frt board to match the neck.
A dab of mastik on the nuts of the truss rod stops it ratteling.
Radius the fret board to 16″
The straight side of the channels was routed first. Then the taper was put on the fretboard and the tapering side of the channel was cut.
The taper was put on with a block plane and sanding stick.
A plank of MDF was screwed onto the bench to provide a straight edge and flat surface. The work was screwed onto the MDF to hold it.
This little shim is needed to keep the sides perpendicular in this area.
Marking out the bracing pattern and selecting wood.
Found a rainbow inside! Good sign.
Housing the pieces. Notice the curve on the braces. 3mm but it should have been more I think.
Clamp clamp clamp
Glued up an scoloped.
I made a mistake here and scoloped the high part of the brace. I glued in pieces as a repair and it turned out perfect!
Mapel bridge plate glued in. It is not touching the braces.
The ends are trimmed to fit exactly up to the sides of the guitar.
The braces are housed into the kerfed lining. When it all fits the top is ready to be glued on!
Ow here is a tough one:
Spot anything wrong?
Yes the soundboards is smashed inwards. Looks pretty tough to fix. Especially because my hand doesn’t fit inside due to the stylish, and now annoyingly sharp, fret board end.
The inside reads:
Made in cork
The instrument has an unusual shape and the bracing parern inside seems equally experimental. There is no x brace but rather two braces run down the length of the sound board past either side of the sound hole, under the outside of the feet of the bridge, and taper together towards the tail pice. They stop around where the crack had occured and indeed they run almost patalel to the cracks.
This bracing pattern leaves a lot of freedom for the wood to vibrate around the bridge and I think it may be the reason it has cracked in this way. It is also the reason, I’m sure, for the reported sweet tone of the instrument. Instrument design is always a compromise between the dichotomy of strength and weakness. We want structural integrity and yet need vibrations to transmit sound. A beautiful sounding instrument that breaks reminds me of the flight of Icarus.
Anyway, philosophy asside, I have been tasked with fixing the thing! So I set about it.
Declan has a great technique for this sort of thing. I can’t push it up from the inside so I must pull it out from the outside!
A large cleat of quarter sawn spruce will be glued in to bridge the cracked piece and sure-up the worst part of the break.
It will be pulled into place by a guitar string wound onto a guitar machine head. A hole drilled in the top of the guitar, the cleat, and a caul for the cleat, will line them all up and allow the pieces to come together by winding up the guitar string:
The cleat is shaped to meet one brace inside and to cover the other so a housing is cut out of it. The break is cleaned up to alow it to come together more easily
Long support beams hold the guitar tuner level on the sound board.
Now the g string I used snapped dramatically as I tried to tigheten it! That shows the pressure the system is under. I used an E string instead. And left it over night…
Sucsess!? The repair is still visible, as expected with such extensive damage. The edges could be sanded down and refinished but let’s string her up first and see if we’ve really succeeded…
Unfortunately when the strings came back under pressure the sound board started to bow down and it was clear that it would break again in the same way so I loosened the tension and put it back in it’s case, feeling a little dejected, but sure a solution would make itself aparent after some time…
About two weeks later I was playing a gig in The Venue, Clonakilty, with TUO Duo. Our ukulele bass caught the eye of a fellow called Steve Pawsey (www.stevepawsey com). It turned out that he was a guitar builder and we got to talking about the mandolin. He suggested that a sound post, similar to that used in violins, could solve the problem.
I had considered the idea before, but this was the impitus I needed. Two days later the mandolin had a large mahogony sound post sitting between the back strip and the cleat I had already installed!