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The soprano ukulele that I made from scraps of wood too nice to throw away (but too small for anything else) turned out to be a nice sounding and surprisingly loud instrument. I thought it would be fun to make another.

The classic wood for ukes is Koa, a tree in the Acacia family, which grows only in the Hawaiian archipelago, although it’s closely related to Australian Blackwood (Acacia melanoxylon) and the wonderfully named – after its smell when sawn – Raspberry Jam wood (Acacia acuminata). I was pretty sure that I remembered having a set of Koa somewhere in my stash of guitar wood and eventually I found it.

After a bit of thought, I reckoned that there would be enough material for two ukuleles – one soprano and one tenor. However, as soon as I began to clean it up with a view to book-matching fronts and backs, I ran into trouble. The Koa had a beautiful and dramatic figure, but it was very difficult to plane without causing tear out. That’s often true of highly figured woods of course, but this this was much worse than usual.

A drum sander would have solved the problem – except that I don’t have one. So I tackled it in the old fashioned way.

First I used this large scraper plane to produce a good surface on the face side of each piece before gluing them up, book-matched, for fronts and backs.

 

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Now, working from the other side, I needed to get them down to a thickness of under 2mm. Fortunately, the wood had been well sawn and was only around 3mm thick so there wasn’t too much material to remove. This Krenov-type plane with a short thick blade set at an angle of 55° performed better than a plane with the usual 45° blade angle. There was still some tear out, but it did allow me to approach the final thickness without too much anxiety.

The plane was made by David Barron and it’s nicely designed with a soft rounded shape that’s comfortable to hold. It has a sole of lignum vitae and a fairly tight mouth.

 

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For the really difficult patches, where the grain was running all over the place, I switched to a toothing plane. This one is a lovely old tool made by Varvill and Son, York, well over 100 years ago. It bears name stamps of two previous owners but it’s in such good condition that I suspect that more of its life has been spent in a tool chest than on the bench. It’s really intended for preparing a surface before laying veneer and, although it’s able to flatten the wildest grain without tearing it, it removes wood very slowly.

 

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To speed things up in the less wild areas, I used an ordinary No 4 bench plane fitted with a modified blade. I’ve written about this blade before, so I won’t repeat myself except to explain that the rationale behind it is that the individual serrations are too small to grab and tear out large chunks of wayward grain while, at the same time, being wide enough to remove material fairly quickly – certainly a lot faster than the wooden toothing plane.

 

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Having got close to the final thickness with this pair of toothing planes,  I finished the surface with a small Lie Nielsen scraper plane and an ordinary cabinet scraper.

 

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Here’s a line up of the workhorses that I put to use.

 

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And here are fronts, backs and ribs ready to assemble.

 

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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.

Most woodworking vices are designed to hold pieces of wood with sides that are parallel. This is a problem for instrument makers because much of the wood they work with is curved or tapered.

So guitar makers frequently use a carvers’ vice, which has adjustable jaws, to get around the difficulty.  Dan Erlewine uses one in his excellent series of videos, Trade Secrets.  And here’s one in my own workshop.
 

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But they’re big, heavy, ugly things (mine is a particularly repellent shade of green) and whenever possible I prefer the simpler solution of a moving accessory vice jaw. This is no more than a block of wood with one gently curved side that allows it to rotate to accommodate the work piece. The flat side is lined with cork and there’s a thin sheet of plywood is glued to the top to maintain it in position while the vice is tightened.

 

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I’ve written about these before (see here) so I’ll only say that they’re easy to make and that they’re very effective in gripping gently tapering (10° or less) objects.

 

The device below  is a little more complicated in having 2 jaws connected at the bottom with a flexible hinge made of leather. It was originally intended to hold the head of a violin or cello  bow while the mortise for the hair was being cut – an invention of Andrew Bellis, who is a bow-maker in Bournemouth.

The 2 jaws are slightly thicker at one end (hence the arrow on the top) which gives it a head start when it comes to accommodating a tapered shape. The flexibility of the hinge allows it to adapt to objects with complex curves. It’s easy to make, too.

 

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Here’s a similar idea but in a more elaborate form. I took the jaws off a small Record vice and substituted cork-lined wood. On one side there’s a permanent version of the moving jaw described earlier. A thin metal bar located by a 3mm rod keeps it in position. I’m hoping the photographs will make things clear.

 

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A couple of photographs of it in action. In the first it’s holding the neck of the soprano ukulele that I mentioned in a previous post. The second shows it gripping the head of a violin bow while it is being re-haired.

 

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I’m pleased with how these vice jaws turned out. And it’s certainly convenient having them immediately available to hold an awkwardly shaped work piece. However, I have to say that they’re significantly more effort to make than the simple devices described earlier. Unless you’re dealing with tapers and curves a lot, it may not be worth the time and trouble.

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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Bruce Hoadley, in his excellent book Understanding Wood, writes that, when people who are thinking about taking up woodcarving ask him which tools to buy first, he tells them to get a set of good sharpening stones. It may not be what they expected to hear, but it’s sound advice. Most woodworking tools are worthless unless they’re properly sharp.

The trouble is that, once you’ve tumbled to this basic fact, sharpening can develop into something of an obsession. Over the years I built up a collection of stones, all acquired in the hope of obtaining a better edge. Many were natural stones, often bought for almost nothing at flea markets or second hand tool shops, but hard to identify. Although some of them were capable of producing a fine edge, most proved tediously slow to cut. As many other woodworkers have done, I discovered that synthetic waterstones and monocrystalline diamond whetstones did the job better and faster.

I didn’t know what to do with my unused oilstones until I heard about Sean Hellman, a professional woodworker based in Devon, UK who’ll make you just about anything in wood from a coracle to a garden bench. Sean has a longstanding interest in these natural stones, and I was pleased to let him have the three photographed below for his growing collection.

This one is probably a Charnley Forrest stone:

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And this may be a Dalmore blue:

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The label identifies this one as a Yellow Lake:

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In exchange for the stones, Sean generously gave me one of the fan birds that he carves. It’s hard to believe, but these birds are made from a single piece of green wood.

 
 

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This is how he does it:

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This splendid photograph was taken by John Runk¹ in Stillwater, Minnesota on an 8 x 10 plate camera in 1912. I came across it in a book, The Photographer’s Eye written by John Szarkowski. Unless the chap in the hat is unusually short, these pine boards must be around 3 feet wide and 15 – 18 feet long. The saw marks run straight across the boards which made me wonder how they had been cut – not with a circular saw obviously. Were large bandsaws in operation at the beginning of the 20th century?

Buying wood a few months ago, I realised that I didn’t know much about modern methods of conversion of timber either. Here are a couple of photographs taken in Andy Fellows’ wood store in Gosport, Hants². He has supplied me with quite a lot of the wood that I’ve used in recent guitars including the Madagascan rosewood for this nylon string guitar and the beautiful walnut for this copy of a 19th century guitar by Panormo. These boards aren’t quite as large as those in Runk’s photograph but they’re still pretty big and I’ve only the vaguest idea of how he goes about transforming them into the book matched guitar sets from which he lets me pick and choose. Next time I visit, I shall try to find out a bit more.

Sometimes, when handing over an completed instrument to its new owner, I catch myself wondering whether they have any idea of the time and trouble that has gone into making it. (Of course, it’s enjoyable time and trouble so I’m not complaining. Even so … ) But I suspect that instrument makers and woodworkers aren’t any better. When we buy wood we’re more likely to whinge about the price than to acknowledge the efforts and skills of the people who selected the log and converted it into sets of conveniently workable dimensions like those below.

1. There’s a brief biography of John Runk here.

2. Andy Fellows also sells wood at his on-line shop, Prime Timbers.

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.

At the beginning of March I posted a few photographs of dovetail joints that, at first sight, look impossible to put together, let alone take apart. As I said then, there’s no real trick to them; it’s just that the assumptions one makes about the parts of the joint hidden to the eye turn out to be wrong.

Here’s the double dovetail disassembled:




And here is the triple dovetail:



Ingenious and amusing, but rather short on practical applications.

While on the subject of the apparently impossible, here’s another teasing puzzle that woodworkers can make to annoy their friends. It consists of 3 pieces: a cylinder, a symmetrical double cone and an inclined plane.

Surprisingly, placed together like this, there is no movement in either cylinder or cone. Wouldn’t you expect them to roll down the inclined plane?

The cylinder does, of course, roll down the plane but to take the photograph, I’ve used a ruler as a chock to prevent this happening.

The cone, on the other hand, has an inexplicable tendency to roll up hill. Once again, I’ve used a ruler as a chock to prevent it doing so.

These still photographs don’t really convey the anti-gravity properties of the double cone. For a more convincing demonstration, have a look at this video on YouTube.

Or, in case the link doesn’t work, paste this url into your browser: http://www.youtube.com/finelystrung#p/a/u/0/g7dCCskRMUg

Another useful aid to cutting dovetails is a dovetail marker. Several different designs are available to buy but I like this shop-made one best. Once again, it comes from Robert Wearing’s book, The Resourceful Woodworker (ISBN 0 7134 8006 8), and is fairly easily made from a sheet of brass 1 to 2 mm thick. Its advantage over the type that Lie-Nielsen and Veritas make is that you only have to set out the centre position of the pins on the edge of the board. The triangular ‘window’ of the marker then lets you see exactly where you’re marking out the joint. It works equally well whether you prefer to cut the pins or the tails first – an argument that I don’t intend to get into.

I suppose purists who like to use a steeper slope for dovetails in softwood would need two markers, one at a 1 in 6 slope and one at 1 in 8. I confess that I never bother about this, cutting all dovetails at 1 in 8, regardless of what sort of wood I’m working with.




I’ve been making a few small wooden boxes to give as Christmas presents. They don’t really have much practical function, except as a place to keep pencils or stamps or other odds and ends, but they’re fun to make and people seem to like them. Part of the pleasure of constructing them comes from the small scale of the project. It’s a day’s work rather than a month for a guitar or a violin. And they allow you use up scraps of wood that were too nice to burn but that are too small to make much else out of. They also provide an opportunity to show off a bit, which brings me to the reason for writing this post.

Even people who know nothing about woodwork and cabinetry have heard about dovetails and recognise them as an emblem of craftsmanship in wood. So that’s the method of construction you should use if you want your skill to be noticed.

If you’re going to cut dovetails, it’s much easier if you’ve got a proper vice. Because of the position of the screw and slide bars in most bench vices, it’s only possible to grip the edge of the board that you’re dovetailing. A dovetailing vice, on the other hand, grips the whole work piece, preventing it vibrating and aiding accurate sawing. They are especially valuable for wide boards but they’re good for smaller pieces too. The idea came from Robert Wearing’s book, The Resourceful Woodworker, (ISBN 0 7134 8006 8). He uses threaded metal bars to provide the clamping force but I cannibalised the wooden handscrews from an old clamp that I picked up in a second hand tool shop. The vice is simply cramped to the top of the bench when needed.

I left the screws much longer than necessary for any dovetailing so that the vice would open wide enough to accommodate the body of a guitar when working on the tail stripe.

And, should you be wondering how the boxes turned out, here are a few photographs:


A while ago, I wrote about using a Millers Falls scraper plane to cope with some highly figured cocobolo that I was using for the back of a guitar. It’s an excellent tool for finalising the thickness and it leaves a clean finish even on the most awkward wood. The disadvantage however, is that it takes only the thinnest of shavings so if you’re starting with wood that’s way too thick, you’re in for a lot of time and effort to get to the right final dimensions.

Of course, the usual way to get around the problem is to run the wood through a drum sander. But I haven’t got one, partly because there isn’t room for it in my small workshop and partly because I’m allergic to sandpaper. I don’t mean it literally – I don’t come out in a rash if I touch the stuff – but I do think that there are nicer and quieter ways of shaping wood than grinding it into dust.

Another solution is to use a plane with a toothed blade. This won’t eliminate tear out completely but, should it happen, it’s limited and shallow and can easily be dealt with by a scraper later. Toothed blades work because the individual teeth are too small to grab enough fibres running in the wrong direction to rip out a large lump.

I use a No 4 Record bench plane fitted with a standard blade that I modified to look like this. Put the blade in the vice, cutting edge upward. Take a cold chisel and, against all your instincts, hammer a small gap into the cutting edge every 3 or 4 mm. Then sharpen the blade in the usual way.

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Another way of cutting the teeth is to use a thin grinding wheel in a Dremmel.

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Here are a couple of pictures of a guitar back in zebrano being thicknessed with the toothed blade. If you’ve ever used this wood, you’ll know that the interlocked grain structure makes it very hard to work. With a toothed blade and a wipe of wax on the bottom of the plane, the task becomes a pleasure.

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The marks left by the toothed blade are just visible running diagonally from bottom right to top left. And you can see the linguine-like shavings that are produced.

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Switching over to the scraper plane for final adjustment of the thickness and to remove the corrugations left by the toothed blade.

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Last autumn, I met Konrad Sauer at an exhibition of woodworking and woodworking tools held at Westonbirt Arboretum in Gloucestershire. He’s a plane maker and let me try out the small smoother (shown in the photograph below) on a piece of American walnut. It wasn’t a highly figured piece of wood but the grain was far from obliging. The plane worked perfectly, taking a full width, tissue paper thin shaving and leaving a surface that required neither scraping nor sanding before applying a finish. Even more impressive however, was the plane’s performance when I turned the board of walnut around. The finish this time wasn’t quite as polished – how could it have been? – but the fact that here was a tool that could take a shaving against the grain without leaving areas of roughness and tear out was a revelation. For a guitar maker constantly needing to work highly figured tropical hardwoods to a perfect finish, it was almost too good to be true. Of course, I asked him to make me one and though I try to be patient, I check his website from time to time hoping to read about progress.

The website is full of interesting things but it’s especially worth reading the ‘Nuts and Bolts’ section for his discussion of why he makes his planes almost entirely with basic hand tools. Some of the reasons are obvious: such tools cost less and take up less space in the workshop. Others are more subtle: working by hand, although apparently slower than working with machines, means that an error can be caught before it turns into a costly mistake. Taking an extra shaving with a handplane is much more controlled than using a machine with a cutter head revolving at 3,000 rpm – not to mention safer and quieter. And working by hand allows him to adjust the plane that he is making by, say, making its handle a bit smaller or its blade angle a bit steeper, so that it’s exactly as his customer want it. These are just the same reasons why I build musical instruments by hand.

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