Cheeses on a plate

While I was building the bells for the next two shawms, I had an interruption.  Two friends had been getting around as a couple for a few years and decided to make it official and get married.  All well and good, so far.  However, they wanted something different for their wedding reception.

Lindsay sent me an URL and asked "Could you make something like this, for our reception?".  "Something like this" was a tier of platters 3 or 4 levels high, supporting a range of cheeses and other goodies.  I had not done anything like that before, but technically, there did not seem to be any obstacles, so I said "Yes".


My thought was to find some suitable wood through my local network of contacts, and from this, cut sections of trunk or branch to form the platters.  I was not sure about the strength of the thin slabs and whether these would manage the stresses.  However, if this proved to be a problem I could always use a reinforcing layer of plywood out of sight underneath to hold things together.

So, to find some wood.  My initial enquiries did not turn up anything - this was July (local midwinter) and the wedding was in October. I was starting to think of a backup plan of creating a composite from smaller wood, but this would not have a external bark layer, which had a nice visual effect.

And then, the breakthrough: a colleague asked me if I would be interested in a plum tree that he wanted felled.  Definitely. Some short while later, after some chainsaw work, I had a 400mm trunk section and plenty of 150-200mm limbs.

By now it was August, and the wood was green.  How to dry it as quickly as possible without ruining it? I cut about twice as many slabs as I expected to need (allowing for spoilage), and stacked these with folded newspapers between them in a mild dry place. 

For the next three weeks, I cycled the newspaper layers with dry replacements every day and progressively wicked the moisture out.  Stacking the slabs may also have helped reduce buckling (I think).  No photos of this, sorry.  My attention was elsewhere at the time.

It was very obvious after the first week that the slabs were going to split as they dried.  I made the best of this by making starter cuts to encourage the splitting to happen where it was manageable.

Once the slabs were dry enough to usefully work, before anything else, I had to deal with the splits. I chose four slabs to be the mainstay pieces, and used a fine saw and wide chisel to clean up the splits to be pretty straight.  This left open segments of 30-50 degrees arc. From the unused slabs, I cut segments to match the gaps.  However, thinking the matter through, I could see that cutting segments that would fit closely into the gaps left by splitting was not going to be practical.

This sketch shows the sequence I used to add a wedge segment into a split slab. 

The virtue of this method is that, at every stage of the jointing, both ends of each join are accessible, and each join is an essentially straight cut, which means that it can be dressed by running a saw between the joint faces a few times, and cleaning up with a wide chisel before the glue goes in.

 







  
In this close up, you can see the three way join on the far side of this slab.  Using Gorilla Glue, which is both strong and somewhat space filling, the final joint looks pretty tidy when dressed up.  Since the donor slab for the inserted segment is from an adjacent slice from the branch, the rings and bark could be arranged to be very similar to the host piece.





Here is my intended final arrangement.  I had the platters pretty much sorted out, but had nothing done for the upright pillars. Consulting my stock of wood, I found a piece of birch which had been windfall in a local city park a year or so earlier, which could be made to yield blanks for two of the pillars, but not enough for the third pillar as a single piece.

Here are the slabs doing a bit of a photo-opportunity, with jars and whatever to get roughly the desired spacing.

Interesting to note the difference in the colour of the slabs.  The cut slabs quickly turned this deep apricot colour as they dried, but the inner wood shows up really pale once it is dressed flat again. I guess that this is oxidised starch or something similar.

The first two pillars turned up easily enough, although this piece of wood didn't seem to be the best of the bunch - the grain was not as close as other parts from the same tree.  Also, possibly not helped by me being in a little bit of a rush, since the handover date was starting to loom disturbingly close.

Here are the dressed slabs doing a trial fit with the first pillar.  The central pillar supporting the top slab is also there, slimmer than I had first thought would be necessary.  You might recognise the temporary spacer in the middle background as one of the bell sections for the shawms, described in other postings

There wasn't enough good wood to make the third pillar in one piece. In the end, I made it in three parts: lower half, top stem and top rest.  The assembled pillar was not quite as true as the others, but looked perfectly good enough in the final assembly.


Putting some coats of shellac on them certainly diverted attention from any vagaries of manufacture.

I finally had the slabs to a state that was close enough to ready for varnishing.  I did not want to use a modern polyurethane since it would not have time to cure enough to be sure that it would not taint the food on the platters.  Also, I rather liked the look and feel of the shellac I had been using for other work, and I knew that it was tasteless and very food safe.

A good choice, as it turned out.  After a generous coating on the bark sections, these were transformed from rough dull finish to a subtly gleaming shiny finish that looked very good.  After that, it was almost an anticlimax to varnish the dressed sections of wood, but the pale faces of plum became rich golden coloured surfaces.

And here is the final assembly, just prior to be taken apart for delivery.

Possibly being overcautious, but I had visions of the pillars possibly spreading under the load and creating An Incident at the wedding, so I slipped in a loop of waxed thread around the tops of the pillars to pull them into place.  You can just see the thread around the tops of the pillars.

So to the day of the wedding.  It was at a picturesque small church on Banks peninsula, with views looking out East over the Pacific Ocean.  The weather was brilliant, and the site was beautifully sheltered from any wind of consequence.

Here is the platter set, loaded and ready for action.

 This was an interesting enough project, but doing it again would be less inspiring, since the element of surprise would not be there. 

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.