Sunday, June 21, 2009

Carving the Heel

Pictured here is the result of a couple of hours spent shaping the heel. This is as far as I'll proceed for the time being; I'll carve the neck and fine tune the shape of the heel after the fretboard has been glued to the neck shaft. I've chosen to rough carve the heel prior to attaching the radiused fretboard as it's easier to secure the neck in a vice or clamp it "heel up" to a benchtop without it.

I use a template to pencil in the shape of the heel where it will meet the sides and a second template to mark the outline of the heel cap. Although the intersection of the heel and the sides is critical to the accurate alignment of the neck with the centreline of the body and is crucial in establishing the correct neck angle relative to the bridge, there's a large degree of latitude where the shape of the heel itself is concerned. It's an ideal opportunity to inject some creativity and there are some wonderful examples where luthiers have done just that. Personally, I prefer to keep it simple and a graceful set of curves and a slim, refined look are my primary goals.

I carry out the initial shaping using a variety of chisels, then move to rasps and files. As the heel approaches its final shape I switch to scrapers and sandpaper. Shadows cast on the heel while holding the neck up to a bright light help identify any remaining lumps and bumps. Although I'm aiming for symmetry, I'm not obsessive about it - I'm happy to rely on visual cues such as this to highlight any inconsistencies.


Monday, June 15, 2009

An OM for Maurice

As a music lover as well as a guitar builder, I can imagine no greater reward for my efforts than getting my instruments into the hands of great players. With that goal in mind, here's one of the instruments I'm working on which I look forward to sending to friend and musician Maurice McGovern in Melbourne.

Soundports like the one pictured are becoming commonplace on custom instruments and, having added one to an old guitar of my own, I can vouch for their effectiveness. US builder Matt Mustapick has this to say about soundports:

This concept came originally from the great classical maker Robert Ruck, who puts two small holes on each side of the guitar, very close to where the neck joins the body, rather than one larger hole. The main advantage of the soundport is that it gives the player a "front row seat" to enjoy a strong direct signal from the soundbox. This feature takes nothing away from the forward projection of the instrument. From 20 feet away the guitar is just as loud. For anyone closer to the guitar, it adds a great deal of richness to the sound, owing to the dual sound source which creates a stereo field.

The combination of rosewood with koa trim is one of my favourites and I can't wait to see the effect when a finish is applied; the rosewood will darken considerably and the curly koa will really come alive. The small clamps I use when gluing kerfed linings came in handy for pre-gluing the purfling lines to the koa bindings prior to bending them in my Fox bender. I used Titebond 3 for this job and there was no sign of delamination which can happen with regular Titebond.

The purflings around the perimeter of the top and back are comprised of black-dyed maple and natural maple veneers with a 1mm mahogany centre piece. The five veneers were glued up as a sandwich using Titebond 3. I then cut the sandwich into strips on the bandsaw (a table saw with thin-kerf blade would be better) and ran them through my thickness sander prior to bending. On future guitars I'll substitute black fibre for the black maple; the maple gave way on the outside of some of the tighter bends. Luckily, I took the precaution of bending a few spares at the same time.

The overlay on the rear of the headstock strengthens the splice - not that it really needs it - and also obscures any glue line where the headstock joins the neck shaft. It's a much cleaner look as well as another excuse to use more of that beautiful koa!


Sunday, June 14, 2009

What's on the Workbench

Never one to complete a project before moving onto the next one, I currently have a number of instruments at various stages of completion:
  • 14-fret 000 - Australian Blackwood back and sides, Sitka Spruce top
  • 14-fret 000 - Claro Walnut back and sides, Sitka Spruce top
  • 14-fret OM - East Indian Rosewood back and sides, Engelmann Spruce top
  • 12-fret 00 - Claro Walnut back and sides, Engelmann Spruce top
  • F5 mandolin - Maple back and sides, King William Pine top
My excuse? As a hobbyist luthier, my choice of finish materials is limited due to lack of access to a spray booth with an explosion-proof fan, etc. I've been down the nitrocellulose path before in more reckless times, but I've had time since then to contemplate the health and safety issues associated with use of that material. As a result, the unfinished instruments have banked up while I explore the alternatives best suited to my hobbyist status, more cautious approach and limited workspace.

I used Birchwood-Casey Tru-Oil successfully on several earlier instruments - it's very forgiving and can be brought to an attractive sheen - but, ideally, I'd like to find a finish I can spray safely and ticks all the boxes where ease of application, appearance, durability and repairability are concerned. A tall order perhaps, but I've finally bitten the bullet and ordered some of Grafted Coatings' KTM-SV, a water-based urethane which I've heard encouraging reports about. Luthiers Mercantile now stock it in addition to Grafted Coatings' KTM9, a water-based acrylic lacquer which promised much but, despite the best efforts of any number of talented builders over a number of years, has not delivered dependable results. Although it still has its advocates, I've read enough negative reports now that my own unopened tin of KTM9 will be thrown out in favour of the KTM-SV I'm currently waiting for. For an excellent discussion of KTM-SV, have a look here.

I hope to post a few pictures of works-in-progress from time to time, as well as share methods and jigs which have helped take the guesswork out of a particular process or have contributed to a more consistent outcome. And, who knows, perhaps this blog will chronicle the completion of my first F5!