More Shawms - really about tuning, this time

I was going to run the post on staples and tuning together, but the stuff on tuning was taking too long to come to me, so now they are split into separate posts.

Remembering having tuned the first shawm, I was in a mixed state of mind about doing this next pair.  On one hand, I had a working reference for where holes should pretty much be, and I knew that mistakes were almost certainly not terminal.  On the other hand, I was not completely impressed with the playability of the first shawm, and wanted to make the next ones better, as far as tinkering with the tuning would allow.

For practical reasons, I planned to continue to use bassoon reeds, and the staples had been designed on this basis, although I was playing the first shawm enough by then to get a feeling that a bassoon reed was not the ideal form.

I took measurements off the first shawm to where the holes were, using the end of the staple as a datum rather than using the end of the bell as I had done for the first one.  In retrospect this was an obvious thing to do, but it does rather require that you have a working unit to measure, which had not been the case for the first shawm.

These are the numbers.  If you are making a shawm, treat these as starting points only, and be prepared to fiddle.  All dimensions are in millimetres, and the holes number from the top down.

Hole number	Distance from staple	Diameter
1	111	4.1
2	165	7.3
3	184	7.3
4	236	8.0x7.7
5	274	7.5
6	303	7.6
7	337	7.4x7.7
Tuning (2 holes)	416	8.3x8.7+7.3x7.9
Resonators (2 holes)	485	7.0+7.0

A pair of dimensions for a hole mean that it is somewhat elliptical, and these are the lengths of the axes.  I drilled the pilot holes in at right angles to the axis, but several holes, no. 4 in particular, have had the inner part of the hole angled in the direction of the reed.  This was a compromise between keeping the outer holes in a place where fingers can readily reach it, while getting an acceptable pitch without a huge hole (which would be more difficult to cover).

The first placement of the holes is best done in a single session using the same reed.  This should not take more than two hours or so.  Don't tinker with the reed too much, other than getting it sounding sufficiently well over the first octave range of the working shawm that you do have. If you don't have a working shawm, this is harder to do...

Since it was never going to get easier, I sealed the inside of the bore by plugging the narrow end and pouring in a measure of thin shellac, and rotating the instrument to thoroughly wet the inside of the bore.  Then a basic coat on the outside to avoid marking the wood with grubby fingers during tuning.

I set up a template in a CAD program of where the finger holes should be, and printed a 1:1 overlay.  With this taped on in the right place, putting the pilot holes in becomes a doddle.

Here is a shot of the second of the pair with the template taped on and tape markers for the resonators and tuning holes near the foot.  Holes are bored straight through the paper template, and it can be rubbed out of the way where not wanted with a gentle application of a rasp.

The hole positions have been rotated around in an bid to improve the fingering of the right hand on the more widely spaced lower holes.  Compared to other factors affecting tuning, this has next to no effect.

The left hand shawm is essentially complete, and you will see that the number 2 hole has been remodelled with wood filler.

Tuning works from the bottom up, so the resonator holes went in first (I have since read that these are more important than I first realised, and there will be much more about this in a later post).  Then the tuning holes, which set the bottom note "all fingers down" pitch.  Some messing around here will be needed to get a reasonable "C".  "Reasonable" means something close to a C for wind pressures that the reed and player can comfortably handle.  This amount of wind pressure becomes the amount of puff that should be used to tune the remaining notes, if the instrument is to be usefully playable.

Here is the first of these two shawms, close to complete in tuning, obviously before I reworked the no. 2 hole.  All the vital tuning tools are to hand: a selection of twist drills from 4.0 to 8.0mm in 0.5mm steps (out of the picture to the right), round and half-round needle files for cleaning up the inside ends of the holes where they enter the bore, water capsule to keep the reed wet while the next hole is bored (near the bell on the left), staple (out of harm's way at the top), and a little electronic keyboard as a pitch reference (out of frame to the left).

It's important that the holes have clean edges, particularly where they enter the bore.  When a hole is first drilled, there are usually whiskers at the bottom end, which are pushed back where they are difficult to reach from the outside.  I dealt to these with a rod of 6mm steel which has the end ground to a 60 degree angle and the sharp edge of this honed and stropped.  By running this rod in from one end or the other, it becomes quite easy to either trim the whiskers off directly with the cutting edge, or to push them across the hole, where they can be cleaned off with a small sharp file from the outside.

When I drill a new finger hole, the rough tuning is done against the keyboard reference, but the final tuning is done against the lower holes already cut, by playing an ascending scale and tuning the new hole so that its note sits comfortably in the scale with a similar intonation to the lower holes.

Small details: when I tuned the first of the second set of shawms, I would spin the twist drills in the forward direction when drilled the holes.  All good, but it would leave an untidy edge on the outer end of the hole.  I treated all these by shaping a small depression across each hole (visible in the photo above).  Visually this was not altogether good. 

For the tuning of the second of the shawms, I would spin the twist drills in the reverse direction when starting the hole.  The trailing edge of the twist drill is still sharp enough to cut the wood well enough, but leaves a cleaner edge to the hole.  The remainder of the hole was cut with the drill spinning forwards.  This is no problem to do with most electric drills.  The result is a cleaner hole, with no need for an extra depression, as you can see here.

I can't say that it makes any real difference in the feel of the instrument, but it looks better.

Finally, here they all are, together.  As you can see, the later shawms have slightly more compact bells than the first one, but have much more sleek lines, and generally look slinkier.

Musically, they are much of a muchness, and playability on any day depends much more on how the reed is feeling than anything else.

From this, I am deducing that I have done as much refining of the shape as is worth doing at the moment.

The next area for improvement is in the reed.  This is not an area that I know a great deal about, and I will need to consult and research.

The new shawms have gone to homes in the Barony of Ildhafn (Auckland, New Zealand), and their new owners will be coming to terms with getting good sounds from them.

To be continued.

More Shawms - staples and tuning

The staple is the thing what holds the reed, and launches its sound down the bore.  In these shawms, I made the staples quite separate from the body, so that I could tinker with construction details and make mistakes without writing off a lot of work.

I have not seen this arrangement in any old images or modern reconstructions of shawms, but there is no modern construction technique required, so it could have been used in period.

Remember the kumihimo bobbins from earlier?  Never mind.  Here they are again, with one end turned down to shawm size (about 30mm diameter), and the unwanted end removed and a rebate turned in the body which is now about 15mm diameter.  There's also a 3mm hole through the middle down the drill press using the flat end as a reference (which still managed to emerge slightly off-centre, grumble). 

The guts of the staple is a metal tube.  I made this one by wrapping thin copper sheet around a 4mm file. One end needs to have a taper in it to match that of the reeds being used.  I am using bassoon reeds, in the absence of anything better (more on this later), and I made a mandrel to match the reeds' taper by filing down a steel bolt in the drill press.

The other end of the tube needs to match the bore of the body reasonably well, so that there not too much discontinuity between the staple and the bore.

These are conflicting requirements, and are not easily met in a single piece of tube - well, not one that I can readily make, anyway.  I made these staples in two parts, each with the requisite taper, or lack of it.

The two pieces of rolled copper are sprung together, heated in a soft gas flame and a small amount of solder flowed in to hold them.  The trick is to keep the amount of solder "small", i.e., put on what looks like an inadequate amount and trust that it will flow all the way to the end of the seam.

With a 16mm spade bit, it was the work of only a minute or two to form the socket in the top end of the body of the shawm.

With a serving of linen, generously dosed with archers' wax (mixture of beeswax and rosin - sticky stuff), the staple is ready to fit, as seen here.  The shawm and staple seem to have acquired a coat of shellac since the last photo, as well.

The straight part of the staple tube is a snuggish fit inside the bore of the shawm.  I "glued" the tube into the body of the staple with some thick shellac, which took rather longer to set than I had expected.  If I use this staple design again, I would use straight rosin or pitch or even hot-melt glue to fasten the tube.

The next step is tuning the shawms, to be told in the next post.

More Shawms - reaming and turning

When I show these shawms to people, one question many ask is how the internal tapered hole was made. I tell them that I push in a tapered steel bar and turn it by hand round and round and round until it is done. This often leads to a short blank silence as though I am being deliberately obtuse, but here is my proof.

 I used the same two sizes of reamers from the first shawm making. Here is the larger one with a handle clamped on.  As I mentioned the first time around, the handle allows a lot more control and torque to be applied.

 And here it is in action, getting on toward the end of reaming.  When the reaming is complete, virtually the whole length of the reamer will have entered the hole, so there is still some work to do.

This thicker reamer is easier to use since it is stiffer and does not flex much.  The thinner reamer used to shape the narrow end of the bore tends to twist if I force it too much.  This time, I did the wide end shaping first, and then put in the narrow reamer on the end of an extension (sorry, no photos for this).

Here's the extended smaller reamer, and you can see the twist on the working part.  I just straighten it out in the vice and carry on - more carefully, for a while.

The essence of all this is that it is all pretty low tech.  The reamer material is just mild steel; no hardening is necessary.  I have honed the big one once, but the narrow one is still on its original sharpen from when I made it.

This particular shawn had the curved bore, and it was obvious from turning the narrow reamer that something unusual was happening inside.  In the best of worlds, there should be a seamless transition between the part reamed by the wide reamer and the narrow reamed part.  Because of the curved bore, this one had a bit of a step.  Again, nothing much to be done about it, but carry on and hope.

 Looking down the throat with the reaming complete. I used several grades of rasp to extend the bell's flare down the throat to produce a smooth transition.

You can see that it is a bit off-centre from the curved bore, and not quite circular, since getting an even rotation was a little difficult.

 After the reaming, the composite body workpiece went back on the lathe.

Here is a view looking into the bell, showing a circular packing piece held in place by friction with the inside of the bell, as a transition between the driven centre (not quite visible on the nut in the foreground).  This simple arrangement worked remarkably well and did not slip significantly while I was doing the finishing turning.

 Here is the workpiece with final depth cuts made all along the body.  This was actually quite an exciting part of the work, since the transition from a roughly shaped piece to a slinky, silky smooth result all happened in the space of less than an hour.  All of a sudden, the chrysalis was transformed into a butterfly.

 The "butterfly" stands on the right here with the original shawm in the centre, and with the workpiece for the second shawm on the left, which has been bored but no more.

To bore the second body, I just clamped it on the bench, put the long 6mm auger in an electric drill and just bored it by sighting along the length.  Whether by luck or skill, this produced a much straighter and centred bore than the first one.  Reaming was straightforward, and I was able to get a pretty good smooth taper all the way along the bore.

 Here is the second shawm glued up and back on the lathe, well advanced in final turning.

Just 30 minutes later, it looked like this.

I have to say, at this point, I was pretty well pleased with the look and feel of these.  So, here are a couple more gratuitous images of the turned bodies.

You can see some filler on the right hand one, dressing a spot where I had cut a little too vigorously during the rough shaping.


Since the timber was recovered building framing, there are several nail holes in both pieces, so there are actually spots of wood filler all over both of them. No-one has noticed or commented on this at all.

A worm's eye view of the first shawm, showing the internal shaping of the bell.


Next stage: doing the staples and reeds at the other end. Not so easy!

More Shawms - long boring

Since I was making these shawms to be joined up as a single unit, the body pieces of wood were longer than in the first one, which had a midsection joint (see this old post).  The lathe bed was long enough, but I wanted to make some improvements to the long 6mm drill.

I had made a drill for lengthwise boring the first shawm by extending a 300mm auger with some steel rod.

This is the joint formed with some copper shim wrapped around the rod and soldered together.  It was strong enough, but required an oversized hole to enter the bore, which defeated quite a bit of the point of being able to make long bores.

This new joint was made by lapping the shafts for about 15mm and brazing them together (reclaimed my gas plant, ha ha), giving a substantially uniform joint (after grinding off the high spots).

 Here is the blank for one of the shawms, mounted in the lathe with the hollow centre.  The bed is long enough, but not too long. Notice that the drill guide and the workpiece are not far apart, and this probably contributed to the drilling problem to be described.

With my son Francis working the lathe's treadle again, I lead the drill into the end.  The boring started well enough, and the first 300mm was easy enough.  After that, things went a bit sour, with the drill seeming to present lots of friction and the shaft getting very warm.  I greased it with some candle wax, which made a bit of difference, but by no means not a complete solution.

Also, the drill became more difficult to withdraw to clean out dust, which rather suggested that there was a curve or kink in the bore, somehow.

Since parts of the bore needed opening up anyway, I ran in a 10mm reamer to widen the hole.  This reduced the drag on the 6mm rod for a while, but there was still this feeling of a curve or kink.  The bore should have been 560mm in length, but I gave up at about 450mm.

At this point, I wasn't sure that the workpiece was actually going to be usable, or how off-centre the bore had become.  I took a length of 3mm brazing rod, filed a flat on the end, and used it in an electric drill to extend the bore all the way through.  As you can see in the picture, the brazing rod has come through well off centre, but not so much to be unusable, so I carried on.

I finished the boring with an electric drill and some brute force. Sighting through the bore, there was a definite curve, deviating nearly 6mm from true.  Acoustically, I guessed/hoped that this would be tolerable, but the reaming would be interesting.

 Jumping ahead, here is the body and the bell being joined.  The body piece has been shaved down approximately with sideaxe and drawknife, centred on the eventual path of the bore.  I turned a tenon in the wide end to mate with a 30mm socket drilled in the end of the bell with a spade bit.

I tried holding these pieces together in a furniture cramp for gluing, but could not get the two pieces to sit squarely together reliably.  I could have made some supporting blocks or something, but this arrangement in the photo was easier to do, mostly. It  has the clamping force applied centrally, via the nylon cord running down through the bore to the weight. The force is only about 3kg-wt,  but it was enough.

I used a modern polyurethane glue (Gorilla Glue), which is plenty strong enough, with some space filling ability as well.


Let's leave it alone to set and come back in the morning...

More shawms - a brace of them

About the middle of 2009, I had the first shawm to a working state that was good enough to make me consider making some more.  I wanted to see what level of improvement I could achieve, based on my experience with the first one.

Differences I planned were:

1. do it in one piece, which is a more period style
2. focus rather more on the detail of the staple and reed end of the instrument, and less so on the bell end, since this is more critical to the final performance.
3. make two at the same time, to see what consistency could be had.

These would still be trial runs, so I planned to mostly use rimu wood again (see Dacrydium_cupressinum), and I still had reasonable stock of well aged rimu to work with.

Easy parts first

Doing the bells would be a simple start, while I thought out the detail of the other end.

Here is a 4" x 4" composite slab being prepared.  It has been centre bored already, hence the groove for the hollow centre visible here. The G clamp and steel angle is a basic rest for the end turning of the bell, and has been improved on since this photo was taken.

Taking the bell profile from the original image from Trevor Robinson's book (see this earlier post), I made saw cuts through the block to about the right depths, and snapped and chiselled off the waste wood.

This photo shows the right end still in a relatively raw state, but the left end has some more accurate depth grooves turned in it, and I have done some rounding down.

Some time later, here are the bells, still siamesed, but with all the external roughing out done (but still oversize, since I hadn't decided the detail of the main body).  I have shaped most of the inside of one end, as much as was worth doing by end turning. Note that I have replaced the G clamp and steel angle with a more elaborate (and more robust) crosswise tool rest for end turning.

Once I had taken the internal shaping close to a final finish, I snapped off the internal nubbin (wot the fixed centre is poking into) and sawed the bells apart so the other one could be turned around and hollowed out.

Then there was a distraction, in the form of a commission which meant that nothing happened with the shawms for about four months (I will talk about this distraction in a later post because it is interesting in itself).