Saturday, December 26, 2009

First shawm - Intro and Design

Background
These first posts are a copy of a another little website I had, which showed the record of how I made a my first shawm.

This project has been on my "to do" list for a long time (decades), so I can't be accused of rushing into it. I am publishing this so that a number of interested people in the Kingdom of Lochac and elsewhere in the Known World can see how it is coming on.

If you don't already know, the shawm is one of a family of mediaeval and renaissance woodwind instruments. Some other members are the Rauschpfeife, Hirtenschalmei, Bombarde, Gaita. What these instruments have in common is being fairly loud and not particularly cultured. You can read more about it at Wikipedia or Musica Antiqua.

Design
I know that there are kitsets available to make shawms and other old-fashioned instruments. To me, this seemed to defeat the major purpose of making, which is do it from the ground up, or close to.

My original inspiration came from Trevor Robinson's book "The Amateur Wind Instrument Maker", many years ago. Most people in the old instrument making community seem to know of this book, and there are a few opinions about how good his designs are. At this stage I can't judge, but they look plausible. I will be referring back to this book in several places as I go along.


In the book, he describes the dimensions for two sizes of shawm, a small musette, and a larger soprano shawm in F. I chose to make the soprano shawm. The drawing is not exhaustively detailed, but the general dimensions are there.


I started out by drawing up a full size plan based on the key dimensions from the sketch, but I could see that continually taking intermediate dimensions was going to be tedious.




I scanned this sketch and pasted it into my CAD package. I scaled the image to make the marked dimensions agree with the real dimensions.

Once that was done, I could overlay lines on the image and tinker these until they were a good general fit to the sketch and not dependent on spot measurements.

Once the key lines were in place, I could construct other critical dimensions as I required.


The drawing suggests a body made in one piece, but looking at the size of the bell relative to the rest of it, I couldn't imagine that the makers would have cut away all that nice wood. I am sure that the bell was probably made in one piece and the rest of the body was made in a another piece, with a lot less wastage and effort, and the two parts were married together and glued..

In any case, for convenience of storage, I planned to make my one in two separable sections, splitting at about the 400mm mark just above the two sided holes visible in the drawing.

As I went along, the number of construction lines and dimensions on the working plan grew and grew as you can see below. From the CAD package, I could also print 1:1 plots of particular pieces, to form templates for checking the actual shape.

Materials
Traditionally, woodwinds are made from some dense or finely grained timber such as boxwood or rosewood.

Since this first shawm was really a trial run, and I expected to make several mistakes, I didn't want to use a top quality wood. So I used some sections of rimu framing timber that I had recovered from a friend's building renovations. This timber is over 30 years old, hence is reasonably seasoned and stable, and there were a couple of lengths with no major flaws which would serve nicely.

I would not be too surprised to find that this timber makes quite a serviceable instrument in the end. We'll see.

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