Friday, September 23, 2011

The Morin Khuur Part Six

The purfling channels are cut by hand using a simple marking gauge and the waste is removed with a tiny chisel. Rather than standard violin style purfling I decided to fill the channel with black veneer for a bold outline.
I sealed the wood using a thin coat of shellac as a barrier. Here, I'm working on building up the yellow colored "ground".  The classic Cremonese instruments usually have this base which increases the optical depth of the finish and gives a dramatic golden effect.  Using artist's  pigments in cadmium yellow and ochre, I mixed a glaze using oil-based wiping varnish as the medium. There's very little pigment - just enough to tint while preserving transparency. A couple of thin coats wiped on with a rag gives the effect I'm looking for.

The back and front, ground in place and ready for body coats of reddish-brown varnish.

Tuesday, September 13, 2011

Morin Khuur Part 5

In recent days I've been making some fittings. Carving the bridge was straightforward. It's quartersawn maple and resembles a violin bridge, though slightly squat and flattened to accommodate two strings in the same plane. I've never carved a violin bridge before. They're typically purchased from a supplier and only need a little work to custom-fit them to a particular instrument.

 I suppose a pair of guitar bass-tuners might be a modern update, but I think the protruding ears of the traditional peg complete the aesthetic of the head nicely. These have been roughed out in pear and still require some work to bring them to completion. Here's a view of the back of the head.
Strings are an issue. The morin khuur is traditionally strung in horse hair. This can causes issues with tuning stability, as they're hygroscopic and continually changing in dimension. Also, they wear quickly and it's difficult finding suppliers. A repair shop that repairs cello and bass bows frequently might have it hanging around in the required 36" (900mm) lengths, but I decided to use nylon monofilament to make a pair of strings. This is 0.20mm (.008") 4lb test fishing line.  I set up a couple of dowel standards the required distance apart and wrapped it around, trying my best to keep the tension even.  A total of 70 strands was used for the treble string, 100 for the bass. (So, 35 and 50 turns respectively).  Some sources suggest tying or braiding the ends in attempt to make stringing a little easier. I've opted to make an overwrapping of about 1/2" (12mm) on each end, and secure it with a little cyanoacrylate glue. It worked like a charm. The extra looped material on the end was snipped off and the finished string has a neat, threadable appearance.
The tailpiece is another lovely piece of pear. This will be hinged to the bottom block rather than using tail gut, to simplify restringing. It's bored for the strings and there's a recess chiseled into the underside to accommodate the knots which will hold them in place.