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Several years ago,  a friend who lives in an old farmhouse in rural Oxfordshire asked me to make a table to go in her sitting room. We agreed that something in  English Oak in an Arts and Crafts  tradition –  simple lines, stopped chamfers , exposed joinery –  would fit with the character of the room. David Simmonds of Interesting Timbers found me some  figured tiger oak to make a book-matched top for it. There’s a photograph of the finished piece below, although unfortunately it doesn’t show the table in the room for which it was intended.

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I mention it  because I’ve been thinking about the design of a couple of smaller tables to go in a different sort of room in a Victorian house in a city. This time,  I wanted something quite the opposite of the table above: light rather than heavy and elegant rather than sturdy. Looking for ideas,  I found this Shaker table in Christian Becksvoort’s book, The Shaker Legacy. Like many Shaker pieces, it’s attractive in its simplicity although, according to  Becksvoort, it isn’t very stable probably because it only has a narrow stretcher hidden behind the drawer.

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And I liked the unfussy lines of this mahogany dining table by Roger Heitzman, which appears  in  500 Tables (published by Lark Books), despite the fact that it’s several times larger, and much heavier-looking, than what I had in mind.

 

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Taking elements from both these tables, I sketched out some ideas and made a rough prototype in soft wood, experimenting with the proportions and dimensions until I got close to the look that I was trying to achieve.

 

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This version, in sycamore,  is on the way to being finished. It still lacks a proper top – I’m hoping to find some fiddleback sycamore to complete it. In the mean time I’m making do with a  sheet of  MDF painted white.

 

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The curved stretcher is secured at each end by a tusk tenon and an ebony wedge, which turns the flimsy looking legs into a surprisingly rigid framework.

 

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To relieve the slightly monotonous look of sycamore, the stretcher carries a simple chip carved pattern between two beads worked with a scratch stock.

 

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I’m making another version in oak. When both tables are finished I’ll  post some more photographs.

 

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In the 1930s, the Head of the School of Furniture at the Birmingham College of Arts and Crafts, Mr A Gregory, wrote two books about woodworking: The Art of Woodworking and Furniture Making, and (shown above) Constructive Woodwork for Schools¹. I bought second-hand copies years ago when I first got interested in woodwork but  I hadn’t looked at them in a long time until I got a request for a chair suitable for a young child.

 

Constructive Woodwork for Schools  contained a simple design for exactly what was needed.

 

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I was amused (and, as things progressed, slightly irritated) by Gregory’s remark  ‘It it is not a very difficult piece of work’.  He’s right, I suppose,  in that it’s largely mortise and tenon joinery. But there are 24 of these joints to be cut and adjusted and, because the front of the chair is wider than the back, they’re not all at right angles. The business of fitting the arms and making the doubly curved top rail isn’t completely straightforward either.  I certainly didn’t find making this chair a breeze, and I should have thought it would have been a fairly taxing task for a schoolboy. Or perhaps I’m underestimating the standard of woodworking 80 years ago?

Here are the individual components and the chair assembled dry. The wood is English oak.

 

 

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And here it is glued up and  finished with a couple of coats of Danish oil. The seat is woven out of seagrass.

 

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Happily, the client seems satisfied.

 

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¹ I assumed that these two books would have been long out of print but, in fact, new copies are still available and there are lots of reasonably priced second-hand copies on Abe Books  too.  The books may be a little dated in their approach but I thought that they were well worth reading. I recommend them, particularly The Art of Woodworking and Furniture Making, to anyone wanting to develop their skills in designing and making wooden furniture,  especially if they’re attracted to work in the tradition of  Edward Barnsley and the Arts and Crafts movement.

Since writing about Bang, Ai Weiwei’s enormous installation at the 2013 Venice Biennale constructed entirely out of traditional three-legged stools, I discovered that he had produced several smaller sculptures using the same piece of furniture as the basic repeating unit.

 

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I’m not sure why Ai Weiwei is so fascinated by these stools but one can’t help admiring the skill of the designers and woodworkers who brought these sculptures into existence.

 

I’ve no ambition to make these stools into sculpture, but after completing a single scaled down stool (see earlier post)I thought I’d make a larger version to use in the workshop. Here it is. The seat height is 22 inches and the legs are splayed at 8º from the vertical, which makes the proportions taller and narrower than the original. The legs and stretchers are Douglas fir and the top is English Cherry. It’s finished with a couple of coats of Danish oil.

 

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I hadn’t realised, when I wrote about Ai Weiwei’s Bang in my last post, that traditional three-legged Chinese stools had featured in Popular Woodworking a few years ago. Thanks to Mike for commenting and alerting me to the articles.

At the end of the piece on Ai Weiwei, I’d said how much I liked the design of three-way stretcher and added that I might make such a stool for the workshop. So it was extremely useful to have a warning that these stools aren’t as easy as they look.

I started by making a full size drawing for a stool with a final height of around 10 inches (top of seat above floor) and a 10º splay to the legs. This is around half the height of those in Ai Weiwei’s installation but I reckoned it would be big enough for any constructional difficulties to become apparent.

First I made the three way stretcher, leaving each of the pieces over length. This is straightforward mortise and tenon joinery, complicated only by the fact that angle at which the stretchers meet is 60º.

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Then I marked out and cut the tenons at the peripheral ends of the stretchers. The popular woodworking articles say that these tenons need to be angled so that they point at the imaginary centre of the equilateral triangle that the stretchers make. I have to say that, although I followed this suggestion, I’m not completely convinced that it’s necessary. Would a Chinese carpenter making a utilitarian bit of furniture have gone to the trouble to do that?

Obviouusly, the marking out also needs to allow for the fact that the legs are splayed and don’t meet the stretchers at right angles.

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Next I marked and chopped out the mortises in the legs, and fitted legs and stretchers together. It was only at this point that I noticed that each of the three legs and each of the three stretchers were identical to one another. Had I tumbled to this fact earlier, marking out would have been easier.

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I’ve only got a baby-sized lathe, so I couldn’t make a round seat. Foolishly, I made it octagonal instead. It’s not a disaster but hexagonal would surely have been a better shape for something with 3 legs.

Here’s the stool assembled dry.

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And here, after gluing and cleaning up.

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I painted it with a warm grey undercoat, top coated with a flat white eggshell and finally cut it back with fine wet and dry paper to give it a slightly distressed look.

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The stool is strong, stable and light but, at this size, not much use for anyone but a young child. However, I’ve learnt how to build one and I shall make the next twice the height.

 

Click on thumbnails below for larger versions of the photographs.

A couple of years ago I saw Ai Weiwei’s installation “Bang” at the Venice biennale and I’ve been meaning to post some photographs of it ever since. It was shown in the French pavillion at the Giardini della Biennale.

 
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Nearly 900 traditional Chinese three-legged wooden stools had been ingeniously joined together to make a huge three dimensional lattice work of wood.
 

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A closer look to give a sense of how it was put together.
 

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And here’s a more detailed view of the joinery of these stools.
 

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What is it about and what does it mean? Well, the most compelling interpretation I’ve heard came from a friend who said that it looked as if these traditional domestic objects had been picked up by a great wind. She saw the installation as a visual parallel of the way economic development in rural China was sweeping aside old ways of life.

If you think that’s too straightforward, here are some comments from the art critics:

‘The single stool as part of an encompassing sculptural structure may be read as a metaphor for the individual and its relation to an overarching and excessive system in a postmodern world developing at lightning speed’.

‘Weiwei’s “Bang” criticizes modern throw-away culture, which has replaced artisans and craftsman with industry and factories. Hand carved wood has been replaced by disposable plastic and aluminum. Weiwei arranged the handmade stools in chaotic bursts and arcs as a metaphor for the industrial world that has spiraled out of control as industry and technology develop at incredible rates.’

‘Ai Weiwei’s work ‘bang’ employs 886-three legged wooden stools made by traditional craftsmen whose expertise is now something that is rare to find, and has installed an expansive rhizomatic structure which speaks of the increasing volumes of organisms in our world’s megacities. The single stool can be interpreted as a metaphor for the individual, and its relation to an overarching and excessive system in a postmodern world which is developing faster than it can keep up with.’

 

Still, whatever you think of the installation as art, the stools themselves are rather attractive. I especially like the three way stretcher, which can’t be that easy to construct. Perhaps I’ll try making one for the workshop.

Fitting a door into a carcass that isn’t perfectly square is a common task for cabinet makers, but it’s rare that the problem is as severe as this or on such a large scale. So I take my hat off to the Venetian joiners who installed these doors in a palazzo near the Church of Sant’ Alvise in the Cannaregio sestiere of Venice.

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The crypt is the oldest part of Winchester cathedral, dating from the 11th century. In a pleasing contrast, it contains something entirely modern – a mysterious life-size statue of a man standing upright, looking down at a pool of water held in his cupped hands and contemplating the reflections he sees there. The sculptor, Antony Gormley, created it from a plaster cast of his own body. After the cast had hardened, it was strengthened with glass fibre and covered in sheet lead. He talks about the technique here.

I’m grateful to Winchester-based photographer Joe Low (www.joelow.com), for letting me use the image below. He took this spectacular photograph of the statue in the winter when the crypt was flooded.

 

 

My friend Gill Robinson, a professional artist (and enthusiastic amateur guitarist) who also lives and works in Winchester, incorporated a witty allusion to Gormley’s statue when she designed a guitar label for me at the end of last year.

 

 

And for clients who might prefer something more traditional, she produced a scraperboard drawing of the west front of the cathedral.

 

 

Here’s one of Gill’s luminous landscapes – a watercolour of Welsh mountains. More of her work, including portraits of guitarists Mark Eden and Christopher Stell can be seen here.

 

My son, who is an engineer working on the design of big diesel engines, tells me that it’s all too easy, especially with CAD software, to draw what seems a brilliant plan – only to meet derision when someone realises that it can’t be manufactured. You can imagine the sort of thing he means: a nut where there isn’t enough space to get a spanner in to tighten it; or the need for a long bolt in a place with insufficient clearance to get it into the hole.

As someone who works with wood, I enjoy teasing him with the complete opposite: something that self-evidently has been manufactured but that looks impossible. One example is the captive screw here. But that’s a bit of a cheat because it depends on exploiting the remarkable elastic properties of some woods when treated with heat and moisture. Better are the apparently impossible double and triple dovetails that I wrote about a year or so ago.

Here’s something in the same vein that can be sculpted out of wood with nothing more than a sharp chisel. Or, should you have one handy, a 5-axis CNC milling machine will do the job almost as well – see here.

For larger images, click on the thumbnails.

The chap in the photograph below, sporting a magnificent walrus moustache, was my great-great-grandfather. I don’t know exactly when he was born or when he died, but I do know that he worked as a cabinet maker in London and later in Plymouth during the second half of the 19th century.

 

 

Several pieces that he made are still in the family and among them is this decorative wall bracket. I’m not sure what it was meant for – probably a small clock or an ornament.

 

 

Quite apart from the pleasure of owning something made by a woodworking ancestor four generations earlier, I’ve always liked the bracket for its nicely judged proportions.

 

 

And I admire his neat solution to the problem of bringing everything to a point at the bottom of the bracket.

 

 

Needing a table for a narrow hallway a few years ago, I borrowed his design for a larger version in walnut.

 

Click on the thumbnails below if you’d like to see larger pictures.

The low Autumn sunshine streaming into my workshop last week showed this oval walnut bowl in such a flattering light that I couldn’t resist taking a photograph. The bowl was being carved on the bench because my lathe isn’t big enough to turn a piece of this size.

Mind you, carving lets you do things that wouldn’t be possible on a lathe, as the photograph below shows. It’s taken from David Pye’s book The Nature and Art of Workmanship (ISBN 1-871569-76-1) and the author carved the dish out of the wood of the wild service tree, Sorbus torminalis. Service wood is not a timber that I’ve ever seen, although I understand that it was once sought after for harpsichord jacks.

I wasn’t attempting anything nearly as ambitious as Pye’s dish. What I had in mind was the egg-like form that Barbara Hepworth frequently used in her sculptures – but on a much smaller scale and as a utilitarian object rather than a work of art.

Here’s a photograph of the completed bowl, which has been finished with clear French polish.

To see a larger version of these photographs as a slideshow, click on any of the thumbnails below.

Footnote

1. Thanks to due to the anonymous photographer who posted the picture of Barbara Hepworth’s garden in St Ives, Cornwall on Flickr (http://flic.kr/p/7J4gud).

This is the back way in to the Ca’ del Duca, a palace off the grand canal of Venice, begun in 1467 but never fully completed. The stylish way to get there is by water taxi but it’s quite as nice and a lot cheaper to walk, which is what I did to see Luxembourg’s exhibition at this year’s Venice Biennale – Le Cercle Fermé by Martine Feipel and Jean Bechameil.

Like most of what was being shown in the Biennale, it turned out to be an installation rather than a conventional exhibition but I have to admit that it provided a mildly amusing experience. You walked along corridors with undulating walls, got disorientated by halls of mirrors and nearly lost your balance navigating wonky floors. It was supposed to challenge our notions of stable constructed space and to make us look differently at the world when we leave. There are more photographs (and some pretentious artspeak) here.

Two of the rooms were especially interesting to furniture makers. Chairs and chests of drawers had been made to look as if wood had a melting point and they’d been left too close to the fire. They were still recognisably chairs or drawers, although obviously you couldn’t use them for sitting on or keeping things in. Indeed, part of the point was that they’d be completely useless for any practical purpose.

I shall leave you to decide whether this is a clever way of encouraging us to think in a fresh way about familiar objects or whether Feipel and Bechameil are just playing a prank.

There was however, a wonderful floor in one of the rooms. Not a wonky one to throw you off balance but a laid wooden floor that had been part of the Ca’ Del Duca in its days of glory. It hadn’t been looked after very well and my photograph isn’t very good but I couldn’t help thinking that it was rather more interesting (and enduring) than the chairs.

Having established, to my own satisfaction at least, that it would be asking for trouble to make a steel string guitar without a truss rod, the next question was which type to use and whether to arrange to get access to it at the top of the neck or the heel.

My friend Peter Barton, who makes beautiful steel string guitars in Yorkshire, recommended the Hotrod, which is a 2 way adjustable truss rod available from Stewart-MacDonald and looks like this.

But there were a couple of reasons why I had misgivings about this device. One was that it weighs over 100g and I thought it might make a small or medium sized instrument too heavy in the neck. The other was that it’s 11 mm deep and, although it would be easy to rout a deep enough slot to accommodate it, there wouldn’t be room to glue a fillet over it. The top of the slot would have to be covered by the bottom of the fingerboard and I worried that, when the rod was tightened up it might split the fingerboard or cause a bump.

To check, I made a model guitar neck out of a scrap of softwood, routed out a slot, installed the hotrod, glued on a pine ‘fingerboard’ and tightened up the trussrod as hard as I could.

It worked fine. My anxieties were unfounded: no splits or bulges in the fingerboard, even though it was made of nothing more substantial than cheap pine, and I could put a curve in the neck in either direction.

Still, there’s no getting away from that fact that it’s heavy.

An alternative, which is less than half the weight of a hotrod, is a simple tension rod. This what’s recommended by Jonathan Kinkead in his book Build your own Acoustic Guitar (ISBN 0-634-05463-5), where he gives instructions how to make and install it. I liked this idea because of its simplicity and light weight, and because it’s easy to arrange to adjust it through the soundhole, which means that there’s no need to excavate the headstock to provide access to the nut.

If you go for this solution, you have to find a way to anchor the rod at the top of the neck. Kinkead recommends a metal dowel tapped to receive the threaded end of the rod. I made one out of silver steel and repeated the earlier experiment.

It’s easy to install, although it’s important to judge the depth of the hole for the dowel accurately to avoid drilling right through the neck.

And it seemed to work OK too, although obviously it’s only able to bend the neck in one direction. However, when I took the fingerboard off, this is what I saw.

The fixing at the top end of the neck had been pulled out of its cavity and had begun to travel down the neck. Of course, this experimental neck is made of softwood and the problem might be less severe in a real mahogany neck. Even so, I thought there had to be a better solution.

It was the shape that was wrong. The cylindrical nut had acted a bit like a wedge. When I made a rectangular shaped nut out of mild steel, it stayed put.

As you can see, the first nut was unnecessarily wide. A narrower version worked just as well.

That’s what I decided to use in this guitar: a tension rod made of 5mm studding, anchored at the top of the neck with a square nut and adjusted through the soundhole. The nut at the top of the neck was silver soldered to the studding to prevent it moving during any adjustments at the lower end. Tension in the rod is controlled by turning a 5mm column hex nut bearing on a substantial washer at its lower end.

This arrangement worked well in the finished instrument and was more than powerful enough to keep the neck straight against the pull of the strings. Next time I make a steel string guitar, I shall be tempted to use 4mm studding instead of 5mm, which would mean even less weight in the neck.

James Gordon, an engineer, materials scientist and naval architect, wrote two books that I highly recommend. I was about to write …to woodworkers but, actually, I highly recommend them to anyone who has the slightest interest in buildings, ships, aeroplanes or other artefacts of the ancient and modern world. My copies have been read and consulted so often that they’re falling apart. They are The New Science of Strong Materials or Why you don’t fall through the floor (first published in 1968, but still in print: ISBN-13: 978-0140135978) and Structures or Why things don’t fall down (first published in 1978 and also still in print: ISBN-13: 978-0140136289). Both are written for a non-expert readership and there’s very little algebra or mathematics. They’re fun too: Gordon writes clearly, wears his learning lightly and the text is spiced by his whimsical sense of humour.

The New Science of Strong Materials has many interesting things to say about the properties of wood and why it’s such a wonderful and versatile material. There’s stuff about how wood is able to cope with stress concentrations and limit crack propagation, about how glues work, the distribution of stress in a glued joint, and many other things of deep background interest, if not of immediate practical significance, to people who use timber.

The second book, Structures, is equally gripping. It explains how medieval masons got gothic cathedrals to stay standing, why blackbirds find it as much of a struggle to pull short worms out of a lawn as long ones, and the reason that eggs are easier to break from the inside than the outside. Of more direct relevance to woodworkers is its straightforward account of how beams work – which means that, if you’re thinking of making something like a bed or a bookcase, you can calculate whether the dimensions of the boards that you’re planning to use are up to the load they will have to bear, which is obviously useful in making sure that your structure is strong and stiff enough.

Slightly less obviously, it’s also helpful in giving you the confidence to pare down the amount of material that you might otherwise have used. A common fault of amateur woodworkers, it seems to me, is that when designing and making something small, they tend to use wood that is far thicker than it needs to be, which means that the finished object looks heavy and clumsy. Conversely, when making something large, they tend to use wood that is less thick than it should be, and the structure often ends up rickety and unstable.

Knowing a bit about beams might also be advantageous for guitar and violin makers. Here’s an example: take a strut or harmonic bar, rectangular in section, that you’re intending to glue onto the soundboard of a guitar. How is its stiffness related to its shape and its dimensions? What’s the best way to maximise stiffness while minimising weight?

Elementary beam theory tells us that, for a given length, stiffness is proportional to the width of the beam and to the cube of its depth. So if you double the width, the stiffness also doubles. On the other hand, doubling the depth, increases stiffness 8 times. If stiffness is what you’re after, it’s a lot more efficient to make the bar deeper than it is to make it wider.

This cubic relation between depth and stiffness could be something worth keeping in mind when planing down soundboard braces after they’ve been glued. If a brace is, say, 6 mm high to start with, planing it down by 1.5 mm to a height of 4.5mm will reduce its stiffness to less than a half of what it was originally. And shaping the braces to make them triangular or arched in cross section also reduces their stiffness considerably.

Mind you, like so many attempts to understand guitars from a scientific point of view, things rapidly get complicated. A structural engineer with whom I discussed the matter agreed with what I’ve just said about the depth of the beam being a powerful determinant of its stiffness. But he pointed out that where a beam is an integral part of a structure, the stiffening effect is much greater than you would guess from calculations that assume the beam is simply supported at its ends. This is certainly the case of guitars, where the braces are glued to the soundboard along their entire length and clearly count as an integral part of the soundboard structure. In such circumstances, he explained, the overall stiffening effect provided by multiple braces will be large and might well overwhelm the influence of the stiffness of any individual brace.

I thought that this was a very interesting idea and that it might begin to explain why so many different bracing systems work remarkably well. In Roy Courtnall’s book, Making Master Guitars, he give plans of soundboard strutting taken from guitars by a number of famous makers. Superficially they’re fairly similar, all being based on a fan-like pattern of 5, 7 or 9 struts. There are minor variations, of course. Some are slightly asymmetrical, some have bridge plates and closing bars and so on. But the  biggest differences lie in the dimensions of the braces. Courtnall shows a soundboard by Ignacio Fleta that has 9 fan struts and 2 closing bars which are 6mm in depth and an upper diagonal bar 15mm depth. By contrast, a soundboard of similar size by Santos Hernández has only 7 fan struts 3.5mm in depth and triangular in section. Applying simple beam theory would lead one to guess that Fleta’s bracing would add more than 10 times the stiffness that Hernández’s does. But perhaps that’s a misleading way to look at it. If one were able to measure or calculate the stiffness of the whole structure, by which I mean the soundboard with its bracing when attached to the ribs, the difference in stiffness between them might turn out to be much less.

It’s a question that might be tackled by finite element analysis and I’d be glad to hear from anyone who has tried. Some work along these lines has been done on modelling a steel string guitar, which at least shows that the approach is feasible.

In the meantime, without a proper theory, we’re stuck with the primitive method of trial and error. Below are some of the bracing patterns that I’ve experimented with. All produced decent sounding instruments but I’d be at a loss if I were asked which particular tonal characteristics were produced by each of the different patterns. It may be that William Cumpiano was right when he wrote (in his book, Guitarmaking, Tradition and Technology):

Specific elements of brace design, in and of themselves, are not all that important. One has only to look at the myriad designs employed on great guitars to recognise that there is no design secret that will unlock the door to world-class consistency.

All this means that I’ve been arguing in a circle. Perhaps the conclusion is that beam theory isn’t very useful to guitar makers after all. Still, if you take up the recommendation to get hold of Gordon’s books, the time you’ve spent reading this post won’t have been entirely wasted.

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