Brun Part 3: End Boxes

Part 3 of the story of how I built my first instrument is going to cover the main wooden frames of the instrument ends; the bellows frames and the walls of the action boxes. I came up with what seemed like a clever plan on paper, but quite a few things went wrong along the way leading to a lot of fiddly corrective work and a couple of slight cosmetic issues in the finished instrument. The next instrument is definitely going to involve some significant changes in the way I build the end boxes.

I had read that good quality vintage instruments were commonly built from sycamore, typically with decorative veneers like ebony or rosewood on the outside, though for this instrument I decided to go with plain solid sycamore and try to use nicely figured pieces of it for the most visible parts of the walls. I struggled to find a timber supplier that stocked quarter sawn sycamore, though after much searching I found a place thirty miles from me that had a stack of roughly 2 ¾” thick slabs that had been plain sawn and kiln dried. I went and searched through them and picked out one taken from the middle of the tree, so it had two quarter-sawn (ish) sections either side of the pith.

I used my circular saw to cut off a section and remove the pith (the centre of the trunk, where the growth rings become very small). If you click on the next picture to zoom in and look at the growth rings, you should be able to see what I mean. The areas where the rings meet the surface at a right angle are known as quarter sawn, and on sycamore they will show pretty figuring after planing it smooth.

I next used my wimpy hobby-grade 9″ bandsaw to further break the chunks down into a set of thin boards approximately 3″ wide. It just barely succeeded, cutting very slowly with a great deal of groaning and stalling. I have since bought a much more powerful 12″ bandsaw that will make this sort of operation a breeze on future instruments.

I cut more of them than I needed so that I had a selection from which to work around knots and pick the prettiest faces to be visible on the outside of the instrument. After ripping them on the bandsaw I stacked them with air gaps around them and let them acclimatise for a couple of weeks; this proved to be a good idea because they definitely warped a little in the first few days.

After drying I picked out the nicest ones and planed the best face flat, revealing the medullary ray flecks and occasional ripples:

I mitred the ends, using the planed face as my reference:

Then I cleaned up the mitres and trimmed them to exact length using a special 45° shooting board I made for the purpose:

Trial assembly gave me my first real feel for how big this instrument was going to be relative to my hands:

Here’s where my clever plan begins. I had the idea to cut various rebates and steps and sound holes and things, and even the tapered area of the bellows frame using the CNC mill, before gluing the boxes together. This part actually went fairly well, apart from me messing up the first one due to a programming error. The main problem was that it took quite a lot of work to do the CAD and CAM to program the machine (there were actually six different programs due to the differences between the sides: left left, left right, right left, right right, tops, and bottoms). You might also have noticed that I used sycamore for both the action boxes and the bellows frames: I’ve since learned that it is common to use a lighter, cheaper wood for the bellows frames; if I’d done that I could have still used the same technique by gluing a strip of sycamore and a strip of whatever secondary wood together before machining them as if it was a single piece.

Trial assembly of all the sides before gluing:

Gluing. Here’s where things started to go wrong. The sides seemed to warp slightly when I put the glue on, making it extremely difficult to get them to line up perfectly. My first attempt was clearly a mess so I broke them apart before the glue had dried, washed the glue off, and tried again.

Second attempt didn’t look too bad at first:

But on closer examination, most of the joints were slightly squiffy, some more than others. It may not look like a lot, but it caused me all sorts of headaches further down the line.

Unusually, the instrument has two reed pans per side. This meant I had to make a pair of dividing walls for the bellows frames:

Next I cut the boxes apart into their three sections: the bellows frame and the two halves of the action box. I was a little nervous about this step but it went smoothly. Those slots routed in the walls are there specifically to make it easier to cut the boxes apart.

Incidentally, I didn’t know at this stage how deep the reed pans were going to be so I made the bellows frames fairly deep to be on the safe side. They probably could have been 5mm shallower in hindsight. This caused me a bit of a headache later on because I ended up having to accurately shim the bottom of the reed pan recesses on both sides because they were both deeper than the reed pans I actually made.

Next I had to inlay the captive nut plates in the bellows frames, and drill the bolt holes in the action boxes. All sorts of things went wrong during these operations, some of them because the frames weren’t perfectly square, some because my milling machine wasn’t big enough to get to all of the walls without turning the boxes 180 degrees. I’ll definitely be working on coming up with an easier and more reliable way to do this operation for the next instrument. The worst thing that went wrong was one of the bellows frames came loose from the (inadequate) clamps and the router bit tore a chunk out of the inside of the wall.

I had my finger on the emergency stop button and managed to hit it before it had done too much damage:

I repaired it by cutting a section out, gluing in a new piece, and planing it flush:

The repair is hidden on the inside of the instrument, underneath the chamois leather gasket.

With the nuts installed, I was able to bolt the boxes together and lightly plane the outsides to get the walls to match up nicely (zoom in to see the nice figuring):

I slightly rounded all the corners so it feels comfortable to hold:

The outside of the bellows frame needed planing to taper it down slightly and round the corners where it meets the bellows, which are deliberately slightly smaller than the boxes and have rounded corners.

I then lightly French-polished the action boxes, leaving the bellows frames bare because I needed to glue the linen and leather to them. After all the difficulties I had polishing the end plates, I was starting to get the hang of the technique by this point and did a much more satisfactory job of polishing the action box sides. If you zoom in you can see how it really brought out the figure of the wood. The dye in the meths still made the finish look a little bit purple, though!

I made a rookie mistake at this stage: as you can see in the previous photo, the bellows frame walls perfectly meet the action box walls with no step. What I should have done was to plane the action boxes a tiny bit smaller, so that when I glued the leather on, the leather would have been able to come right up to the underside of the action box without the edge being visible. I tried to work around the problem by skiving the leather down to virtually nothing where the frame ends, but it didn’t work perfectly and the join between the two looks slightly crude. It probably also would have helped if I’d made the end run a couple of mm wider and wrapped the skived edge of the leather around the corner a little, so the edge of the leather end run was clamped inside the joint between the boxes, underneath the chamois gasket.

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Brun Part 2: End Plates and Hand Rails

Apologies for the long delay since part 1 of this short series about how I built my first instrument, Holden Concertinas No. 1, a small rectangular 30 button Hayden Duet. I have now finished the instrument and begun design and tooling work on No. 2, which will be a more conventional hexagonal 30 button Anglo.

First a caveat. This was my first instrument, built from scratch without plans or instructions, in some cases involving materials and techniques that were new to me, not under the direct guidance of an expert (though several experienced makers offered useful advice when I had a specific question). I was constantly figuring out how to do things and building tools as I went along, and sometimes my ideas didn’t work out perfectly, or by doing a process one way I learned something that helped me to see a better way to do it. In some cases I was limited by the tools available to me, and I made a point of making everything myself in my own workshop (apart from the stainless steel screws). I think overall the instrument turned out remarkably well, with a few mainly cosmetic flaws, but there is certainly plenty of room for improvement when I build No. 2. This article is the story of how I did it on my first attempt and what I learned along the way, not a definitive guide to building one yourself.

The wooden end plates were made from 3mm birch plywood (the best quality I could find), hammer-veneered using hot hide glue and a veneer hammer I made myself from oak with a brass blade. The top veneer is a very pretty fir burr (or burl for the Americans), with a cheaper beech veneer on the bottom (you always veneer both sides of a board at the same time to reduce warping; in this case it also helped to thicken and strengthen the board). Unfortunately on the finished instrument the beauty of the pattern is rather hidden by all the piercings, buttons and handles, though there are areas where it is still visible. I dried the board between paper in a simple press for a week or so. After taking it out, it warped slightly, but it was flexible enough that screwing the plates to the rigid end boxes pulled them flat again, and in fact I now find that after a few months being held flat by the boxes, they remain flat when I take them off.

I decided to try French polishing the instrument, and I thought it would be easier to polish the board before I cut out the fretwork (in hindsight this was probably a mistake). This was my first time using the technique. It took a very long time, I made a bunch of mistakes, and the results weren’t entirely satisfactory. I learned a great deal, though, and I’m sure the next one will be better. One of the problems I ran into is that in the UK the sort of alcohol you can buy in a DIY shop (methylated spirits) has a small amount of poison and purple dye added to it to prevent people drinking it. It turns out that if you dissolve blonde (clear) shellac in ordinary purple meths, the dye doesn’t evaporate along with the alcohol, it stays in the finish. The thicker the finish, the deeper the purple, and due to inexperience I accidentally made the finish on the end plates way too thick. Funnily enough the change was so gradual I barely noticed it happening, until I happened to place the polished board next to an offcut of the original veneer! For my second instrument I am planning to try dissolving the shellac in clear ethyl alcohol that I found being sold online for medicinal purposes; it’s quite a lot more expensive than meths per litre, but I don’t need huge amounts of it to polish a concertina.

Next I cut the board into two pieces and stuck my cutting templates to them, then drilled all the holes on the CNC mill. Ignore the fact that the mounting holes appear to be in the wrong places – there was a reason I had to do that, which I’ll talk about in the next instalment. The fretwork design is my own, inspired by Indian mandala designs. Circles within circles within a circle within a square. It may not be to everybody’s taste but I am rather proud of it. The space below the fretwork was left empty because I knew the handles needed to go down there, but I didn’t drill any mounting holes at this stage because I hadn’t yet figured out exactly how or where they were going to attach.

I couldn’t drill the button holes to final diameter on the CNC mill because the drill bit I had was too long for the Z height of the machine, so I instead drilled small pilot holes and then manually enlarged them on the pillar drill. I was a bit worried the face veneer would splinter out when the drill bit entered the board, but I used a sharp brad point bit, fed it in gently, and they all turned out perfectly.

The end plates fit into rebates in the end boxes (in order to hide the cut edge of the plywood), which meant I had to do some fiddly manual trimming of the edges using a block plane and shooting board to get them to fit in perfectly without a gap.

I cut the fretwork by hand with a vintage fretsaw. It may look tedious but I actually really enjoy this part of the job!

Here is a little video clip of me working on the piercing while listening to Lady Maisery on the stereo (you have to click it again to stop it playing or it will automatically repeat):

After I’d finished piercing and peeled the sticky paper templates off, I found that the thick shellac finish had gone rough, so I decided to sand it down and try polishing it again. 

The result was a significant improvement, though not totally perfect. In hindsight I probably should have kept going, taken all the shellac off, and completely started from scratch, but I was loath to do that because of the many hours it had taken me to build it up in the first place.

I reamed the button holes out a little from the back using a taper hand reamer, then glued in bushes made from 0.85mm piano bushing cloth. This is a fiddly job that is difficult to do neatly, though I found that I got better and quicker at it with practice. Here’s a quick video clip showing how I did it using hot hide glue. I’m working from the back but aiming to get the front edge of the cloth to sit flush with the front face of the end plate because it’s not possible to neatly trim it flush afterwards.

After the glue had dried, the buttons fit in the bushes but there was too much friction, so I turned a tapered polished brass rod the same size as the buttons and used it in the milling machine spindle at 10,000 RPM to burnish the inside of each bush. This had almost no effect! Second attempt, I made another tapered rod that was slightly larger than the buttons, and waggled it around a bit in each hole. This made the holes just right so the buttons went up and down with hardly any friction or noise. After a couple of weeks I found that a few of the buttons were sticking because the bushing cloth had bounced back, so I repeated the burnishing operation. This second burnishing seems to have done the trick; months later the buttons are still working smoothly.

The extra bit of felt sticking out of the back of each button hole was in some cases interfering with the cross holes in the buttons and preventing them closing fully, so I trimmed them all flush with the back of the plate.

On to the hand rails (I know I’m skipping over the casework and action; I’ll cover those in another instalment). I had an idea to try making more ergonomic handles and spent a while experimenting with a set. Unfortunately they didn’t really work out for various reasons that are outside the scope of this article, but I’ll include a couple of pictures because I think they looked rather pretty.

Back to the drawing board, I decided to make a pair of simple Anglo-style hand rails, but with the ability to adjust them backwards and forwards, and a spacer block that allows the height to be raised or lowered.

The top parts of the rails were made from slightly spalted apple wood from a tree that was taken down in my best friend’s orchard:


The spacers below the main rails were made from contrasting sycamore wood:

While planing the two pieces to match each other, I clamped them together using the same bolts and captive nut plates that would later be used to hold them onto the end plates:

Because the handle could be adjusted back and forth, it didn’t make sense to attach the strap to a fixed point on the side of the action box, which meant I instead had to put the strap clamp screw on the end of the rail. This meant making a captive nut that fit into the end of the rail, and was held very securely by one of the main attachment bolts passing through a cross hole drilled through the nut:

This wasn’t my first attempt at making thumb screws: the earlier ergonomic handles had four larger-diameter screws. I think the final ones I put on the instrument turned out reasonably well, though the knurling isn’t as neat as I’d like due to the knurling tool I bought being a bit too sloppy. I am planning to make a stronger tool with finer wheels before I knurl the screws for the second instrument.

I lightly French-polished the handles and cut the straps from 2mm full grain veg tanned calf skin. I think the shape worked out OK, though I did the decorative creasing around the edge using a tool improvised from an old soldering iron and it went a bit wonky in the curved areas (I’m planning to get or make a better creasing iron before I make the next set of straps).

I found that after playing the instrument for a few minutes the thumb screws started to unscrew themselves. The solution came in a photo I found of a Dipper instrument that had the thumb screws in the same location: a clamp plate like a large washer that is bent around the end of the rail. This prevents the screw turning when the strap moves and looks quite snazzy too! I have since seen exactly the same arrangement on instruments made by Geoffrey Crabb. I put the two bends in the clamp by clamping it in the middle of a toolmakers’ clamp that happened to be the same width as the rail (1/2″).

The final touch on the end plates was to add my maker’s label. The design was hand lettered by my talented friend, Oliver Densham, in a style inspired by the labels used on vintage Victorian instruments. I laser-printed it onto archival grade paper and sprayed it with a special protective lacquer intended for decoupage art, so it should hopefully last a long time.

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Brun Part 1: Introduction

For the past few months I have been hard at work designing and building my first concertina. It has been a long and at times difficult journey, and I have renewed respect for the Victorian pioneers of this complicated little instrument.

The inspiration came from my first client. He wanted something similar to an unusual rectangular 4 ½” by 6″ 24-button instrument developed in the 1850s by the Wheatstone company, the Duett. This was the first concertina with a duet button layout, i.e. one where the two ends have independent keyboards, with some overlap in range. The new instrument, however, was to have the Wikki-Hayden keyboard layout, as many buttons as I could fit in, riveted action, bigger bellows, nicer handles and straps, more attractive fretwork (but not the traditional acanthus-leaf style), and generally better build quality and finish.

After many hours spent in CAD, laying out various different reed pans and action boards, I came to the conclusion that the most buttons I could practically fit in was thirty; fifteen per side. I could have just about squeezed in a couple more chambers into the right hand side reed pan underneath the keyboard array, but there was no way I could place pads over them on the action board. Thirty buttons is unusually small for a Hayden layout so the choice of which notes to include was always going to be a compromise. In consultation with Brian Hayden, I considered a few different layout options before settling on this one, on the basis that it should be usable in the most common folk music keys of C, G and D. The lowest note on the right hand side is middle C.

Over the next few posts, I’m going to cover how I developed and built the instrument.

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Reed Pan Router Bit

I’ve spent hours searching for a commercially-made router bit that has the right dimensions to cut the dovetail slots in a traditional reed pan. It needs to be an unusually small diameter, but if you want to be able to cut the top slots after installing the chamber side walls as it was done originally (some of them undercut the walls), it needs to have a disproportionately long ‘neck’ between the cutter and the shank. On the plus side, the slot is quite shallow so the neck doesn’t need to be ridiculously skinny. In the end I decided to make my own.

I started with a piece of 1/4″ silver steel. After putting it in a collet and facing the end, I used the side of a threading tool to turn the tapered section, being careful to produce a sharp corner without significantly reducing the diameter of the base of the cone. I made it just long enough to be able to cut a 2mm deep slot, to avoid weakening the neck section unnecessarily. I set the tool holder over to produce the desired 60° taper:

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Next I extended some more stock from the collet and turned the ‘neck’. On my first attempt, swarf obscured my view of the work and I accidentally retracted the carriage too far to the right and put a groove in the cone area. There was no option but to start again! The second time, I used the tailstock as a right-hand carriage stop to protect the cone.

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The trickiest part of making your own router bit is producing the flutes without a special tool cutter/grinder machine. I cut three helical flutes by hand with a very small triangular saw file, then hardened and tempered it and sharpened the edges with diamond needle files:

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Unfortunately it didn’t work well at all. It splintered the surface badly, then overheated:

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Back to the drawing board. I studied a lot of photos of commercial dovetail router bits on Google Images and came up with a very different two-flute shape. Here’s a quick clip of me filing the relief angles on the second router bit with my saw file (click to stop it after you’ve seen it once, because the Instagram player auto-repeats):

Filing relief angles onto the Mk II reed pan router bit. Quite a ticklish job. #concertinamaker #toolmaking

A video posted by Alex Holden (@alexholdenmaker) on

And this is the finished bit, after heat treatment and sharpening. The thing it’s inserted into is one of my milling machine’s quick change tool holders:

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This photo shows the reason why it needs a long neck (I made it a bit longer than would have been necessary for this Treble English, in case I want to make an instrument with deeper bass reed chambers at some point):

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The second router bit works pretty well. Here’s a clip of it cutting a reed slot in a piece of scrap pine:

Programming the CNC mill to machine the slots is surprisingly complicated. The CAM software I’m using doesn’t understand how to cut a pocket with a tool that can’t plunge straight the workpiece and needs to enter and leave the edge of the material. I found a way to trick it into doing what I need, but the entire process filled nearly two pages of my logbook, and I need to do it all again for every size of frame I need to cut!

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Another problem I ran into is that the outer dimensions of the antique Lachenal reeds I’ve been copying are a bit variable. Not by much, but a tenth of a mm change in width makes the difference between a snug fit and a loose one. This one fits very well – I can throw the block of wood in the air and catch it and the reed is still nicely seated – but the reed taken from the slot next to it (nominally the same frame size) is loose enough that it would fall out. I think when the instrument was built, somebody must have spent a while individually fitting each reed to its slot. Luckily my CNC mill (which I’m using for both the frames and pans) is repeatable to tight enough tolerances that I shouldn’t have this problem.

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Going Nuts

Quite a while ago I wrote a post about making nut plates for the doorbell project. Since I need twelve of them for a real instrument, and they will need to be accurately inset into the bellows frames, it made sense to program my CNC mill to produce them.

They are made from 2.5mm thick brass sheet. They have an M3 tapped hole in the centre, and two countersunk holes for fixing them to the frames using No 4 x 3/4″ brass screws. This batch of twelve took about 45 minutes to machine:

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Of course, after breaking them out of the plate, they still required a bit of manual cleanup and deburring:

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I tapped them all by hand using my ultra-high-tech tapping jig.

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Here is the finished batch of nut plates, plus one of them set into a piece of scrap plywood the same thickness as the wood I’m going to use for the bellows frames. They have rounded ends so that I can cut the inset using a router bit in the CNC mill without having to manually square up the corners with a chisel afterwards.

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Acetal Buttons

I made a batch of buttons for my first prototype instrument. For simplicity I decided to use solid black acetal (an engineering plastic, commonly called Delrin, though that is a trademark of DuPont) rather than metal. Acetal is used by most modern concertina makers and it has a number of useful properties; particularly ease of machining, low mass, low friction, and low thermal conductivity (i.e. they don’t feel cold to the touch). I believe the top quality instruments still tend to use hollow metal buttons though.

The acetal came through the post in 1m lengths protected by a plastic tube. Long lengths of it are quite bendy. I started with 6mm and turned it down to 4.8mm. Before putting it in the lathe I cut it into 250mm lengths, which was about as long as I dared (shorter would result in more wastage, any longer risks the unsupported left hand end whipping around dangerously). I got nine buttons from each length.buttons2

I did most of the work on my manual Taig micro-lathe. I did a few things differently than usual in order to increase efficiency. For instance I set up both a standard right hand tool in the front toolpost and a parting off tool in the back toolpost so I wouldn’t have to mess about changing tools twice per button.

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I made a couple of simple length gauges to control how much of the stock was protruding from the chuck at each stage, then turned up to the Z axis stop (set up to allow the carriage to almost touch the chuck). The short gauge is for the peg on the bottom of the button, and the long gauge is for the main body of the button. I also made full use of the graduations on the cross slide handwheel to produce the two diameters without stopping to measure the part.

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I made a special jig to hold the button while I drilled and countersunk the cross hole on both sides. It is built in such a way that you can turn it over 180 degrees and locate it using the two pins on the baseboard, which is clamped to the drill press table.

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Although this photo shows a standard jobber drill bit, I found it worked better to first use a smaller, more precise drill press to spot the hole location with a small centre drill, otherwise the bit drifts to one side or the other and you end up with an off-centre hole.buttons7

Finishing the top of the button involved facing off the parting-off stub, hand-sanding to round it off slightly, then flame polishing with a pencil torch to get a smooth glossy finish.

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(Close-up picture of the polished button didn’t come out well – it turns out that my camera’s autofocus struggles to lock onto glossy black objects!).

This video shows the whole process:

Here’s a finished button:buttons8

And the full batch (more than I need for the first instrument – I made extra because I wasn’t sure how many I would ruin in the process, and I can always use the extras for my second instrument):

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After completing the buttons, I now had prototypes of all the parts of a concertina action, so I decided to put it all together in a little test piece:

As well as the crude box itself, I made the pad, samper, grommet, lever, post, spring, felt washers, button, and both bushes. It is currently sitting on my desk as an executive toy, and I find myself reaching out and pressing the button whenever I’m thinking about a problem!

Update: After a couple of days of pressing the button whenever I happen to be at my desk, it definitely operates smoother and easier than when I first assembled it. I think the pad may be sealing more tightly too.

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Prototype Action Lever

I made a prototype action lever. It’s a Wheatstone-style riveted lever hand-cut from 1mm thick brass sheet (the post is 1.5mm; possibly a bit thicker than necessary, but I didn’t want it to distort when I hammered it in).

The hardest part was making a die tool to thread the pad end so that I could screw the leather grommet onto it. Because the lever is cut from thin flat sheet rather than round bar, an ordinary thread cutting die wouldn’t have worked, so I instead made a sprung die set to form the thread.

I started with a 15mm x 25mm x 100mm bar of O1 tool steel, drilled and filed a spring shape on one end, then slit it in half:

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Next I clamped it tightly together in a vice, and drilled and tapped an M2 hole in the middle of the slit, near the opposite end to the spring:
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I put a couple of M5 threaded holes in the bottom so I could bolt it to a chunk of angle iron, then hardened and tempered it to 200C, differentially tempering the spring end to a higher temperature with a blowtorch so it won’t break in use:
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After a bit of experimentation, I found that I could get it to form an acceptable thread if I cut a section of the 1mm sheet to 2.5mm wide (this dimension is fairly critical: 2mm forms almost no threads, and 3mm distorts and creases badly). It works best to hammer the tool fairly hard four times: once with the lever vertical, once each at 30 degrees from vertical in both directions, then a final time with the lever vertical again.
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The lever after sawing it out with a jeweller’s saw, forming the thread, and riveting it to the post:
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The proportions were based on one of the shortest levers in a treble English; most of the levers will have longer straight sections. The straight section is 2mm wide; I had to make the threaded part a bit wider (the tool squishes it narrower and thicker):
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After screwing the grommet on. It is necessary to enlarge the hole in the leather grommet to 1.65mm before it will screw on without using excessive force and damaging the grommet:
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Spring Winder

I made a simple machine for winding concertina springs, inspired by Bob Tedrow‘s video.


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It has a drum with a mandrel sized for the desired coil diameter and a hook on the outside, driven by a crank handle. The small step at the base of the mandrel helps to get the first turn of the coil tight. The adjustable guide plate isn’t strictly essential, but it helps a bit with consistency.

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The raw spring material; 22 S.W.G. (about 0.7mm) phosphor bronze spring wire. It bends easily, is fairly corrosion resistant, and I’m told it lasts a lot longer than brass. At some point I’m planning to experiment with stainless spring steel and other diameters, but I’m sure the phosphor bronze is going to work fine for my initial prototype instrument.

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Step 1; use needle nose pliers to bend a right-angle that will form the ‘pin’ that you push into the action board:

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Step 2; insert the wire into the machine as shown. It’s important that the hooked end is parallel to the face of the drum:

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Steps 3 and 4; turn the crank handle clockwise about 2 1/4 times, then cut the wire off, using the guide plate to gauge where to cut.

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Step 5; use small round nose pliers to form the hook:

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Step 6; use needle nose pliers to bend the hook over at a right angle:

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The finished spring:

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Here’s a quick video of the process:

Sometimes it’s necessary to use an opposite-hand spring because of limited space on the action board. You make these in the same way but doing all the bends the other way and turning the crank handle anticlockwise:

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A few experiments with various arm lengths:

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Prototype Pads

Concertina pads are small discs that cover holes in the action board; when you press a button, it causes a pad to lift off its hole, which allows air to pass through a reed and produce a note. They are made from a sandwich of leather, felt and card. The leather forms an airtight seal against the hole, the card provides a rigid backbone and a surface for the action lever to attach to, and the felt acts as a buffer between the two that stops the pad making an audible slapping sound when it closes quickly.

It took quite a few experiments to find a combination of materials, glue, and procedure that produces satisfactory pads. Along the way I made quite a few pads that fell apart, were too hard or too spongy, and/or were too thick or too thin.

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A pad ‘sandwich’ after gluing:

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I eventually settled on hide glue with some urea added to extend the open time a bit. I soaked apart an antique Lachenal pad and I’m 99% sure it was glued with hide glue. PVA would probably work too, but when I tried it, it stuck well but it seemed to soak into the felt and make it harder. I know others have used sprayable contact adhesive successfully, but it barely stuck at all for me. There’s a bit of a knack to applying just the right amount of glue, and it’s important to brush it onto the card/leather, not the felt, otherwise it will soak up far too much glue and go hard when it eventually dries. Clamp the sandwich as lightly as possible and take it out of the clamp after an hour to avoid permanently compressing the felt. Leave it at least a few hours to dry before punching the pads out.

The leather is thin smooth sheepskin skiver, with the hair side out. The card is 1mm greyboard (I also tried millboard, but it turned out to be made of two layers that delaminated when I punched the pads out). I tried five different wool felts before settling on this one, which the supplier describes as 1.5mm 25 S.G., though it starts out significantly thicker than that and compresses down a bit when you glue it.

I’m punching the pads out using Priory wad punches (carefully resharpened), a lead mallet, and an anvil made from the smoothed end grain of a beech log soaked in boiled linseed oil.

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It works best to punch with the leather side up, otherwise the card distorts and doesn’t cut cleanly.

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It’s important to keep hammering until you’ve cut through the card all the way around.

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A new pad next to a ‘retired’ antique Lachenal one; the new one is a bit thicker and softer, but I think it will quickly compress down to about the same thickness.

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Bastari Repairs

I just finished fixing up a Bastari G/D Anglo for a friend who plays for Anonymous Morris. The aim was mainly to repair a few faults and tune it up, to make it more playable rather than carry out a complete restoration.

The first problem was that the action boxes had split apart in several of the corners, so I cleaned up the joints and glued them back together, adding reinforcing blocks to strengthen them. This was a bit of a delicate job because they were originally constructed with PVA glue and I couldn’t remove any significant amount of material from the joints when cleaning off the remains of the old glue or they would have got smaller and would no longer fit the rest of the instrument.bastari_1

The chrome-plated brass end plates were a bit grubby so I gave them a quick polish:bastari_2

This instrument’s Achilles heel is the aluminium pivots where the buttons are attached to the action levers. Note that these are different from the rubber tube type commonly found on Stagi instruments. Most of them were rather wonky, and the most-used buttons were sloppy due to wear; a few were almost worn through:bastari_3

After discussing the problem with the client, I agreed to make replacements for the most-worn levers. I cut the new levers from 1mm brass sheet with riveted pivot points, so they are unlikely to wear out again. After designing the two sizes of lever and the button insert in CAD, I printed a template on sticky paper and cut them out by hand with a jeweller’s saw.bastari_4

I re-used the top parts of the buttons, which were made from chrome-plated brass with the aluminium pivot glued into a hole in the bottom. The first step was to break off most of the pivot with a pair of needle nose pliers:bastari_5

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Then I put the button in a drill chuck in the lathe and drilled into it with a centre drill:bastari_7

Then a 3mm drill (this was a tiny bit bigger than the original hole, so it left a nice clean surface on the inside of the hole):bastari_8

At a certain point, the drill stopped cutting; this meant that the tip of the old pivot had come loose and was stuck on the end of the drill bit. After withdrawing the drill and removing the loose piece I was able to finish cleaning up the rest of the hole:bastari_9

I sawed the new pivot pieces slightly wide, then carefully filed them down until they were a snug fit in the hole:
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I glued the new pivot pieces in with Araldite Rapid Steel (an epoxy resin that is specifically formulated for gluing metal):bastari_11

I found it easier to work on the action if I removed all the levers apart from the one I was working on at the time. I glued the new levers to the original pads using hot melt glue (this seemed to be how it was done originally), fitted the spring, put the end plate on, marked the position of the hole on the lever, took it apart, drilled the rivet hole in the lever, cut it shorter, riveted the button on, put it back together, and bent the lever until the button was directly below the hole.

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Here’s a quick video clip of me riveting a button to a lever:

And here’s the resulting pivot. I actually made a ‘snap’ tool from hardened silver-steel to form domed rivet heads, however I found that it inevitably made the joint stiff if I hammered it enough to take out all the play. By using lots of light taps with a small ball peen hammer instead, I was able to make pivots that work and feel just right. Note that the mushroomed end of the rivet doesn’t turn; it expands enough so that it is a tight fit in the lever, but there is just enough play in the joint for the pivot to turn smoothly without any noticeable wobble.

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This video shows the difference between a sloppy worn-out pivot and one of my improved brass riveted ones:

As well as replacing ten of the levers, I adjusted the remaining 21 as best I could, straightening and tightening them up as much as possible. Rather a fiddly, painstaking task, and it’s impossible to get them perfect without replacing them all.bastari_13

The bellows had quite a few worn corners, some of which were leaking air, so I glued thin patches on them. I tried to dye the new leather to match the old, but it didn’t work very well: I managed to get the leather slightly darker, but it seemed to quickly reach a point where it didn’t want to absorb any more of the dye.

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Tuning the instrument proved much more difficult and time-consuming than I expected. Some of the reeds were no trouble, but many of them behaved illogically, randomly going flat and muffled, then suddenly going sharper again when I fiddled with them or just after playing them for a while. In hindsight, stiff/sticky valves were mostly to blame for this. Some of the reeds were rather dirty; this one went five cents sharper when I wiped the sticky black dust off it:bastari_15

There was one reed that nearly had me pulling my hair out: it kept going flat by six cents whenever I tightened the instrument’s end bolts down. After trying many different things, I eventually worked out that there wasn’t quite enough clearance between the reed tongue and frame on one side. Somehow, tightening the end bolts down was bending the sound board and applying a force to the reed frame that distorted it just enough to cause the tongue to slightly graze the vent side, which made it sound flat and slightly buzzy.

The finished instrument ready to go back to work, playing traditional English dance music:bastari_16

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