OM Acoustic Build (Mark Bailey Course)

ArchtopDave

Having more or less worked out the Spec, I headed off to David Dyke's for some of the wood. It takes me the best part of 2 days to do this trip, as I live outside Newcastle and he's down in Sussex. I have done this before on another build , and enjoy picking out my own wood.

 First of all, picked out some Cocobolo for the Back and Sides.

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TTony

This is going to be good ...

ArchtopDave

Then fancied Tasmanian Blackwood for the Binding and part of the Rosette. After talking to David Dyke and looking at a number of different woods, I chose Walnut for the laminate strips in the Neck (rest of Neck to be Mahogany). Fortunately, he had a spare side od both woods, so he didn't charge me much for them.

The upper side is Tasmanian Blackwood and the lower one the Walnut.

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ArchtopDave

I used Mark's Bootlegger Acoustic Guitar Templates to make the Body of the Guitar. This is essentially OM in size, but with a slightly larger Lower Bout - the Lower Bout is 16" wide rather than that of a standard OM, which is just over 15".

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ArchtopDave

Once I got up to Mark's place in Scotland, the first job in the Workshop was to join the two halves of the Back together. So a fair bit of time spent on sanding, plus a bit of scraping with a Stanley knife blade,to get the edges of the wood as good as possible. The test of this is to hold the wood up to a light source. This shows up where the high and low spots are. This is one of the parts of making a guitar, where low spots are a particular "pain in the neck", because no matter how good the rest of the joint looks, you've got to sand it all down to get rid of the low spots.

The two sides get clamped together for glueing, though without too much force, otherwise either the glue joint ,or the wood, can split at a later date. Because Cocobolo is a somewhat oily wood, Epoxy glue was used for any glueing involving the Cocobolo. Titebond isn't a reliable glue for Cocobolo, as it can fail and joints open up at a later date.

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ArchtopDave

This photo is a bit on the dark side, but the fine dark line in the middle shows a pretty tidy joint prior to glueing.

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ArchtopDave

Glue excess removed, and then the Back was sanded. The shape of the back of the guitar was then cut out using the bandsaw. On the left, there's a piece of tracing paper with the cutaway roughly traced on it. I'd originally done a full sized drawing with a cutaway shape that I simply created myself, but unfortunately this drawing was lost. Using this rough drawing as a template did lead to a small error in shaping the cutaway, though this wasn't ultimately a disaster.  

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ArchtopDave

Next job : Bracing the Back.

First reinforcement down the centre line.

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You can just see the pencil marks which mark the positions of the Cross Braces. These separate strips of wood are made to overlap the pencil marks a little, so that once glued, they can be accurately trimmed to allow a firm hold of the Cross Braces. Also the gaps at either end are there to allow for the Neck and Heel Blocks.

ArchtopDave

Then clamped and glued. The steel rule, as seen in the last photo and this one, keeps the reinforcing strips nicely lined up with the centre line.

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ArchtopDave

The Back of the guitar is made slightly rounded. This is produced by making the Cross Braces with a gentle curve on one side, so that the Back will be bent to the shape of the Braces when glued and clamped up.

The curve on each of the 4 Braces is produced by using a radiused sanding dish - in this case a dish with a 15 foot radius.

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ArchtopDave

The curve is more obvious here on the longer 2 Braces.

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ArchtopDave

Each bracing joint prepared , so that there's a good fit of the Cross Brace.

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Also if you look carefully , you can just see that the edges of the central Brace have been gently rounded. This will be done to all the bracing so that there are no sharp edges. It's said to reduce any unwanted reflection of sound.

ArchtopDave

With the Braces in place, you can see evidence of the curve of the Braces, as there is more shadow beneath the ends of the Braces.

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ArchtopDave

Next, the fun of glueing the Braces to the Back using Go Bars. The Sanding Dish is used to hold and support the Back in it's new rounded shape.  The fun with Go Bars relates to the fact that the odd one will become loose and fall over as you add more of the Go Bars. Plus, as you check how tight they all are, you can also knock one or two out of position.

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ArchtopDave

The Cross Braces are then shaped - firstly the ends are angled with a good sharp chisel.

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The little block is a convenient measure to show how far the end of the Brace needs to be taken down.

ArchtopDave

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When working on the ends of the braces, the Back needs clamping down on the side that you are working on. Not only to steady everything, but now, as you can see, the Back has a gentle curve to it, and this does not want to be unduly stressed.

ArchtopDave

The Braces then need further shaping, particularly the Braces on the Upper Bout. The Lower Bout Braces need to be more simply rounded. Neat little finger plane to do the bulk of shaping.

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ArchtopDave

Then sanded to finish and also excess glue trimmed away at the same time.

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BigMonka

That's looking great 

Are we getting these updates in real-time or is this a past project?

ArchtopDave

This is a guitar build that I finished a couple of weeks before Christmas. I actually started it at the end of April 2014. There were times when there were significant gaps between my visits to Mark Bailey's workshop. Overall I clocked up 30 days of actual work making it. As you will see soon, I made a rather time consuming Rosette, plus I did Binding and Inlays, which all take time.

ArchtopDave

For the Top, i bought book matched Adirondack Spruce from a small company in the States, who supply a number of boutique builders and they also supply Collings. Not cheap, but looked good plus a good tap tone. Forgot to take any photos during initial prep and glueing, but it's the same process as for the Back. Also all the Bracing, apart from the central strip on the Back, is Adirondack (the wood for the bracing was actually quite cheap - from the same supplier as the Top Wood).