Monday, December 28, 2009

Images a bit slow to load

In these early posts, there are quite a few images, and it can take a while for them all to load and render.  Please be patient.

I will have to remember this for future posts.

Saturday, December 26, 2009

First Shawm - Boring Breakthrough

From my first boring attempt, it was more than obvious that keeping the drill well aligned was the thing.

Another thing was to reduce the cutting rate of the auger so that the workpiece could spin more and help keep the alignment good. To allow this, I ground off the auger's leadscrew to a flat end, and then relieved the cutting edges enough with a file. This meant that the auger would not drag itself in willy-nilly but would have to be pushed, giving more control.

The other major innovation was to get someone else pedalling the lathe, leaving me free to concentrate on managing the drill's progress. Acknowledgements to my son Francis for this.

Here's the improved drill guide fastened properly to the right hand end of the lathe.

Here's a view looking through the hole in the drill guide.

You can see the rear (concave) face of the hollow centre and through that, the driven centre at the other end of the lathe bed, all nicely lined up.

Here's the new workpiece mounted in the lathe.  I didn't bother to cut it down to square, since I didn't know how much wander there would be.

At the right of the picture, you can see the extension to the 6mm auger passing through the drill guide, showing that drilling is already well advanced.

Another view of the drill and drill guide.  Note the fender washer clamped to the drill guide, which provided a fine adjustment for the alignment of the drill.

Another view looking along the drill shaft extension as it disappears into the workpiece.

Initially, I ran the 6mm drill in until it couldn't go any further because of the brass jointing sleeve.

Then I ran in the 10mm spade bit following the 6mm hole as a guide.  I wasn't sure how centred this would be on the 6mm hole, but it didn't greatly matter at this stage since all this part would be reamed out anyway.  As it happened, it did stay fairly well centred.

Having widened the hole far enough in, I put the 6mm drill back in and bored through until it should have been about 10mm from the end.

I drilled a sighting hole crosswise at the driven end of the workpiece, and  there was the borehole, a total of about 6mm off centre.

For a 440mm lengthwise bore, this seemed pretty good to me.

First Shawm - Really Boring now

As well as a hollow centre for the lathe, I needed a long drill or auger to actually do the boring.

Trevor Robinson reckons that the ultimate for this purpose is to use shell augers, and even gives some instructions on how to make a shell auger if you don't want to buy them. Now that I have some experience in the matter, I see these instructions as valid enough but not really giving much guidance with the key aspect, which would be the careful and central sharpening and honing of the cutting end.

My approach was more direct: I went to a local hardware shop and bought the longest 6mm drill I could find, which was an auger about 300mm long.  This was still too short, but was a good start.

I made this auger longer by the simple expedient of fixing a 6mm steel rod to the end of it.  The joint consists of some brass shim wrapped around the shaft, with the whole assembly held together by soft soldering.

My welding plant was out on loan, otherwise I would have made a steel sleeve and brazed the auger and extension together.  In retrospect, this would not have been as good as the brass and solder joint, since it would have been too stiff to adjust for best straightness, without possibly bending the extension or the auger.  However, the brass/solder joint was a nice balance between stiffness and adjustability.

Here is the initial stock length, ripped down to a 50mm x 50mm section, being drilled.  I clamped a basic guide on the end of the lathe to assist with keeping the drill in the right line.

Aligning the bit by eye, I started the bore with a 15mm bit, and turned it with a brace since the lathe did not have enough torque or gearing to turn against this.

When this maxed out at about 150mm, I changed to a 10mm spade bit on a 400mm shank and bored that to its full depth, before changing to the auger.

Looking into the hollow centre.

The initial hole is 15mm diameter, bored with a brace and bit.  Then it comes down to 10mm diameter, drilled with a spade bit with a 400mm long shank.

This provides clearance for the joint in the 6mm auger seen here to pass inside the workpiece.

Things seemed to going along quite well, and I was becoming quite hopeful, when Pop!, the end of the auger appeared out of the side on the workpiece about 70mm from the end.


To see where I had gone wrong, I cut the workpiece into sections , and here they are.  On the left is the tailstock end with a 10mm bore, moving toward the headstock  as you look across to the rightmost end.

It is quite apparant that the hole was deviating right from the outset, and that it actually ran in a fairly straight line until it emerged from the side.  This was sort of good news, since it suggested that better aiming of the drill would greatly improve the result.

First Shawm - Prepare to be Bored

One the interesting/exciting/challenging things about making woodwinds is drilling the lengthwise bore. In this design, this involves drilling a 6mm hole down the length of a 500mm piece of wood, and staying reasonably central.

This drilling really has to be done on a lathe, and to do this, the lathe needs to have a hollow centre to hold the end of the wood, leaving the centre free where the drill enters it.  My lathe, being somewhat hand-built (to be described in a later post), did not have a hollow centre.  So I made one for it.

Out of my "old plumbing" collection, I took a pressure reducing valve and used one of the brass bell housings from this.  This had a nice flat face with three nice mounting holes and a nice cylindrical section which polished up nicely (am I painting a picture here?).  Mounted on a wooden tailstock cut to fit the lathe's bed, it fit the bill very well.

The position of the brass bell housing on the tailstock required some adjustment to make it centred on the existing driven and fixed centres.

I moved all the centres together as shown in this picture.  On the left is the driven centre, and on the right is the hollow centre, and you can just see the point of the fixed centre showing through.

The hollow centre has already been adjusted, by eye, and this was a final check.

This is a view looking back the other way from the picture above.

The fixed centre is in the foreground, pointing through the hollow centre to the tip of the driven centre in the background.

This piece of wood is being prepared to fit into the hollow centre.  The right hand end has been turned down to a snug fit inside the hollow centre.

And here it is, now fitted in place.

This picture shows boring fairly well advanced, and evidenced by the drill shaft extension passing into the hollow centre at the right.

First shawm - Intro and Design

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.

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.

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.

OK, come on in.

To get things going.

This is as much me telling myself what I will be doing with this blog as it is an introduction, so don't feel that you have to concentrate too much here.

I have been a make'n'do kind of person since the beginning. Son of a cabinet-maker, who was son of a foundry man cum smith, who was son of a (very good) stone mason, so there is a bit of a trend there.

In recenter times, I have become involved with the Society for Creative Anachronism ( as it manifests itself in this part of the world. Society members may know me better as Lowrens, of Southron Gaard in the Kingdom of Lochac.

Although singing was my initial avenue for joining the Society, it also has a strong make'n'do ethic which has held my interest and has been a contributing factor to the activities which will be recorded here.

So, cutting to the chase: this blog records the tale of a particular thread of woodworking which started in late 2007, and seems to be maintaining itself comfortably well with no immediate signs of tail off.

Now read on.