Six fold black goatskin bellows with custom papers. Slightly heavier-duty construction to increase stability for fast Anglo playing.
Sycamore end plates with black-dyed tulipwood veneer. Hand pierced fretwork in a traditional-style foliate design.
English yew border inlay.
Simple round-over border shape.
Sycamore action box walls with black tulipwood veneer (more labour than using solid Ebano, but slightly lighter-weight).
Yew handrails with Ebano capping. Leather thumb pads, integral brass strap fixings.
French polished finish.
Brass reed frames.
High quality hand-filed long scale steel reeds.
Sycamore reed pans with parallel Jeffries-style chambers, not tapered.
Sycamore action boards.
Brass sheet riveted action levers.
5.7mm diameter boxwood buttons, slightly domed.
Slotted brass end bolts.
This diagram shows the full button layout. The buttons were positioned to closely match that of the client’s existing 30 button Jeffries, with a custom extra button tacked onto the end of the left hand middle row.
The end plates have a sycamore core veneered with black-dyed tulipwood, giving an ebony-like appearance but with the strength benefits of a laminate construction.
As on all my previous instruments, I hand pierced the fretwork with a fret saw. The fretwork pattern is a new design I came up with in the traditional foliate style; I like it much better than the one I used on the first Blackbird.
The borders are made from English yew wood, giving a striking contrast to the flat black of the end plate.
I used a different border moulding shape, a simple round-over rather than the fancier ogee style. It has a more gentle radius, which means it feels more comfortable on the hand.
The handrails are made from the same yew as the border, with an Ebano capping strip.
It has a drone note controlled by a lever actuated by the left thumb. The routing for this lever proved to be slightly convoluted!
Above the end plate it connects to a simple little forged brass lever positioned out of the way so it doesn’t get pressed accidentally, but not too hard to reach when you want to use it.
The buttons are made from boxwood like on my previous instrument, though this time I simply turned them from solid wood.
For various reasons I started again from scratch with the reed pan and action board layouts. I think the new version works better in several ways, as well as making room for the extra button on the left without resorting to any inner chambers. I have also improved the way I design action levers so that the longer ones are stiffer and less prone to bouncing when playing very hard, without adding a great deal of extra weight.
After building two instruments with aluminium reed frames I returned to brass reed frames for this instrument. Brass certainly adds significantly to the weight, though this instrument still feels reasonably light in the hands. I can’t really say anything definitive about the sound difference, if any, between the two reed frame materials because I haven’t built two instruments that are otherwise identical. My suspicion at this point is that because brass frames are stiffer and have more mass to counterbalance the reed tongue, they may be capable of a very slightly louder and brighter sound, though I reserve the right to change my opinion on that in the future. There certainly isn’t a huge difference between them. The other advantage of brass frames in my experience is that they are a bit less prone to misbehaving due to distortion caused by uneven pressure from the reed pan slot.
There isn’t really a significant cost difference either way, and I currently charge the same for either material. The brass raw metal is a bit more expensive, but I find there is more labour time involved in making aluminium frames. Of course I am talking about comparing reed frames that are equally well-made from two different materials; it is a different story when you compare e.g. top quality 1920s brass framed reeds to gappy mass-produced 1960s aluminium framed reeds.
The left hand pan is fairly densely packed, significantly more so than on the first Blackbird. The pans are flat, i.e. all the chambers on the left side are one depth and all the chambers on the right side are another (slightly shallower) depth. This is how nearly all vintage Anglo concertinas were made, and it contributes to the traditional ‘punchy’ Anglo concertina sound, as compared to the arguably more balanced sound produced by a good quality English or duet concertina with tapered pans.
The small holes in the redundant chambers are just there to reduce the weight a little. I don’t think they make any difference to the sound.
A recent new acquisition for the workshop was an English-made professional quality hot foil printing press, that I bought for the purpose of printing my own bellows papers. I am able to engrave my own printing plates using my CNC milling machine.
My client and I collaborated on the design for the papers used on this instrument; we went with a falling sycamore leaf and seed theme.
I’m really pleased with how nice these look, particularly the way they glitter as the bellows open and close.
Before we settled on the sycamore design I experimented with a few other designs, which are also available for future orders.
A really simple star pattern:
Wave pattern inspired by the traditional Japanese Seigaha design:
The previous printing plate didn’t quite work the way I intended (the thin lines weren’t supposed to have gaps in them), so I tried re-cutting it a bit differently, leading to a second, denser, version of the wave pattern:
Pictish key pattern, inspired by a portion of the carving on the Aberlemno 2 stone cross:
I recently completed a side project I have been working on for quite a while; another conversion of a Wheatstone English to the Müller system.
This one features engraved nickel-silver end plates with a pretzel design by the professional illustrator and concertina player Nina Dietrich.
I have done a small amount of hand engraving in the past, but this design was far more complex than my previous attempts. I built a simple air powered graver to help with the task, and a rotary table to help me follow the smooth curves.
Another new feature of this instrument was 5.7mm diameter boxwood buttons and matching handrails/thumb pads. I really like how these look and feel, particularly in contrast to the metal plates and the black hand straps.
I came up with a simpler strap thumbscrew design for this instrument. The captive nut stands proud of the wall slightly, and the screw intentionally bottoms out before it has clamped the strap tight; this free play allows the strap end to rotate without loosening the screw.
Henrik Müller provided the straps for the instrument to his own design.
Another difference with this conversion was that we moved the buttons away from the hand rails, closer to the top of the instrument. It includes a couple of extra accidental buttons too. What made this possible without ridiculously short levers was that the donor instrument originally had 56 buttons, but we didn’t need to include any of the top notes, which were located around the top ends of the reed pans.
I did need to swap around a few pairs of chambers to enable an action that doesn’t have any levers crossing over other levers.
The oddly placed extra button at the bottom of the right hand is an air button linked to a pair of now-empty chambers at the top of the reed pan. It is quite easy to reach, though you have to retrain your muscle memory to use it because the lowest G# button is confusingly close to where the thumb air button is usually located.
My latest instrument is another Crane duet, this time a traditional-looking 44 button (+ air) with 6 1/4″ hexagonal ends.
Here is its full specification:
44+1 button Crane layout with Butterworth curve and slightly narrowed column spacing.
Seven fold plain black goatskin bellows.
Black walnut burr veneer with black Rocklite Ebano border inlay.
Ebonized beech handrails with integral strap fixings.
French polished finish.
6082-T6 aluminium reed frames with steel reed tongues.
Standard scale reeds on the left hand, long scale on the right hand.
Sycamore radial tapered reed pans.
Sycamore action boards.
Brass sheet riveted action levers.
3/16″ nickel silver capped buttons with acetal cores.
2mm button travel (giving 4mm pad lift at 2:1 action lever ratio).
Black wool bushings.
Tuning: 1/5 comma meantone with root note A=440Hz.
Includes some modifications to standard Crane layout, such as the addition of left hand A2, Bb2, and B2 notes, and right hand B3.
The following button chart shows the modifications from a standard Crane (click to enlarge). Note that the D#/Eb button is not a mistake:
I was lucky to have the pleasure of recording a set of tunes played by the instrument’s new owner, John Thornton from Hampshire. I am really happy with how rich and well balanced it sounds (even more so in person than recorded on a built in phone mic).
I put a lovely black walnut burr veneer on both the end plates and action box sides:
I designed a new vintage-inspired fretwork pattern for the instrument (hand-pierced, naturally):
I came up with another variation on the strap clamping method. It’s similar to what I did on No. 1, but with a leather pad on top rather than a brass plate.
I hand turn the knurled thumb screws, so each set has a unique shape:
The moulded border inlay is made from Rocklite Ebano.
As on the previous instrument, the left hand (with 19 buttons) has a fairly simple action, but the right hand (26 buttons) was a lot trickier to build, with some rather awkward spring placement. It works nicely though, and the short button travel and light action makes it feels very responsive. I’m now using four different sizes of pad: 13, 14, 15 and 16mm diameter, and this instrument uses all four for different pitches. The air button has a 16mm pad, which isn’t huge but it’s adequate for a duet with a few anglo-style bisonoric buttons.
This is the first time I resorted to crossing two levers, and it worked fine, though the perpendicular spring on the air button was a bit awkward to get working reliably (I added the extra staple to stop it twisting and hitting the lever next to it).
The reed pans are both quite densely packed, with one inner chamber on the right hand. I again used aluminium reed frames to keep the weight of the instrument down, though I redesigned them to make them a little stiffer than the last set.
Incidentally any difference in sound quality or response from the reeds in the inner chamber is barely detectable. I think it’s important to keep the chamber as small as possible, put the pad hole over the clamp end of the reeds, and mount the reeds securely. On this one I realised I could just tap holes in the inner chamber reed frames and put bolts through from the other side of the pan, which eliminates any fiddling around with tiny nuts.
I made a new reed slot dovetail cutter, inspired by the reed pans in a very densely packed 56 button Wheatstone English. The step in the profile allows it to cut a significant distance under the side wall next to the tip of the reed without removing enough of the wall to weaken it.
The seven fold bellows hold plenty of air even for heavy chordal style playing.
The finishing touch is a sturdy Italian hard case with custom fitted corner blocks covered with padded velvet, so the instrument is held securely with the bellows evenly compressed.
My latest concertina is a 45 button (+ air) Crane duet in a 6 ¼” (159mm) wide eight-sided frame, with rippled maple veneered end plates and sides, applewood border inlay, and Ebano handrails.
The knotwork-inspired fretwork was designed by the talented illustrator Nina Dietrich.
This chart shows the keyboard layout (click to zoom in):
French polishing really brings out the figure in the rippled maple veneer. Unfortunately a static photo can never fully do it justice. It shows off a beautiful three dimensional effect as you move it around in the light.
I used pyrography (wood burning) with a very fine tip to mark the lines on the wood that give the design its 3D knotwork effect. The trickiest part was transferring the design onto the ends in pencil first, while making sure I didn’t weave under when I was supposed to weave over or vice versa!
In order to reduce the weight of the instrument I made the reed frames from 6082-T6 aluminium instead of brass, and also reduced the thickness of some of the wooden parts and further optimised the shape of the action levers. The total weight came to 1135 grammes; less than Holden No. 3, which had 28 fewer reeds. This did cause some manufacturing challenges; I had a lot of difficulty machining the reed frame blanks without breaking end mills before I found a set of parameters that worked reliably. In my opinion good quality aluminium-framed reeds are no easier or quicker to make than brass and can sound just as good. It may be possible to get slightly greater maximum volume from brass frames (both of equally high quality) due to their extra stiffness and mass, but I don’t think there is a big difference and you are unlikely to notice it when playing at low to moderate volume. I certainly wouldn’t call the use of aluminium frames an ‘economy’ or lower quality option, and if you want a lighter weight instrument it is an option worth considering.
It was quite a challenge to fit all the necessary reed chambers into the reed pans. Not only did I include three more buttons (+ air) than vintage Crane duets of this width normally had (42 buttons without an air button was standard for a 6 ¼” wide hexagonal instrument I believe), but going up from six to eight sides paradoxically reduces the available internal space by a not inconsiderable amount. I had to use a radial arrangement, put two chambers and the air passage in the middle of the pan on the right hand side, and really pack them close together. I also used a shorter scale than I did on No. 2 and made the frames skinnier and the dividing walls thinner.
The left hand action wasn’t too tricky, but the right hand was very challenging and required some creative spring-making.
The surface of the middle button on the right hand side was subtly textured to make it easier to locate your position on the keyboard by touch.
I continue to get better at bellows making with each set I make, and this was probably my best set yet. They feel supple yet firm (if that isn’t too much of an oxymoron), and I am happy with their cosmetic appearance. A novel aspect is that the client provided me with custom-designed papers based on a photograph of one of the end plate veneers.
An unusual feature of the instrument is that both handrails can be adjusted south from their standard location by about ½”. This necessitated some changes to the way the handrails were mounted and a new strap clamping method. It looks a bit unorthodox but it works well and felt comfortable and secure to me. I have also located a source of more supple (but non-stretchy) strap leather.
Incidentally, if you look closely on this picture, it nicely shows off the mirror finish on the French polished Ebano handrails.
I custom-dyed some wool cloth a deep forest green for the button end bushes. It almost looks black unless the light catches it the right way.
Here is a quick video clip of my client testing out his new instrument before taking it home:
I have switched to a better quality hard case, made in Italy. I also fitted four custom-sized internal corner blocks padded with felt and upholstered with silk velvet to hold the instrument very snugly, keeping the bellows compressed evenly and preventing the instrument from rattling around in transit.
This was my most complicated and difficult build so far, particularly due to the density of the right hand side, and the build had quite a few ups and downs and new learning opportunities. I am very pleased with how it turned out in the end. My next instrument will also be a Crane duet, but with six sides, more traditional appearance, and a slightly different button selection.
My latest project was to make a pair of new replacement action boxes for a Wheatstone model 21 English concertina, to give it a keyboard and handrails/straps to the specification developed by Henrik Müller. The conversion was done in a manner that allows the instrument to be easily returned to its original form if desired. As I write this post, Henrik is working on an article for the Concertina Journal that should answer the question of why one might wish to mess with improve upon Charles Wheatstone’s nearly two-hundred-year-old design.
My client wanted the new instrument to have wooden ends, both for cosmetic reasons and in the hope that they would mellow the tone slightly. I designed a new fretwork pattern around the modified keyboard arrangement and handrails, and cut the end plates from a hardwood laminate with American walnut face veneer. This is my most intricate pattern yet.
I made the walls from solid rippled English walnut.
I filled the pores in the walnut with crushed charcoal to give it darker flecks.
I routed the action boards from quartersawn sycamore. The new keyboard has fewer buttons than the donor instrument, so some of the reed pan chambers are redundant (we opted to leave the reeds in them to avoid the risk of them getting misplaced).
I stained the inside of the fretwork piercings dark brown with Van Dyck crystals, and I glued my maker’s label to a thin board that allows me to place it about 1mm below the surface, rather than at the bottom of a deep, dark hole that makes the text difficult to read.
I made the decorative borders from applewood, copying the profile of the edge moulding from the original Wheatstone ends.
I also made the curved handrails and thumb pads from the same piece of applewood.
Henrik convinced me the conventional strap screw in the above picture wouldn’t stay fastened for long with this style of strap, so I came up with something a bit more complicated instead. The new fasteners hold the strap slightly away from the wood and allow the strap to pivot without loosening the nut.
I made a few more small refinements to my action design, mainly to further reduce the weight.
I have made a new tool to draw 3/16″ diameter metal caps for standard English-style buttons. Note that these buttons are unusually short because it is a feature of the Müller system that the buttons should go all the way down flush with the end plate.
French polishing takes a lot of time but the results speak for themselves.
The last step is bushing the button holes – if you do it earlier it’s impossible to avoid contaminating them with polish.
Here’s a comparison between the original Wheatstone action boxes and the Müller replacements:
And here is a quick clip of my client trying out his new instrument:
I’m very pleased with how this project turned out, and if I was building a new instrument for my own use I would strongly consider a variation on this system. One possibility I have considered is to shift the keyboards upwards and add a few extra notes at the bottom end, so the lowest note is C3, similar to a conventional Tenor English concertina.
A few weeks ago I completed my second new concertina. For pragmatic reasons I chose to build an example of what is probably the most popular type of concertina sold today: the 30 button 1 C/G Anglo in a 6 ¼” hexagonal frame. I decided to name this model (and variations on it) the Holden Blackbird in honour of the small family of blackbirds that sing and dance on the roof of my workshop while I am building instruments (no photos of the birds, unfortunately: they are very camera-shy).
Here is the specification of Holden No. 2, the first of my Blackbirds:
31 buttons + air (Wheatstone layout with a middle C drone on the left thumb button).
6 ¼” (159mm) wide hexagonal frames.
All parts other than various screws made by myself in England from high quality materials, either by hand or on my little CNC milling machine (everything visible on the outside of the instrument is hand made).
Traditional long-scale concertina reeds, with hand-filed spring steel tongues closely fitted under a microscope into brass frames. They are loud and responsive with good dynamic range and pitch stability. I don’t like trying to describe tone in words because it is so subjective, but I’d say it has a strong sound without being overly harsh. One player called it, “sort of Jeffries-ish.” I recommend hearing it in person if you can – the iPhone recordings don’t really do it justice.
Seven fold black goatskin bellows with black leather-effect papers. They are supple and don’t have a tendency to spring open, due to building them freehand without a mould.
Black Ebano (a sustainable alternative to ebony) action box walls.
Laminated hardwood end boards (for strength and stability) with American walnut face veneer and a moulded English walnut border. I used different shades of shellac for the central part and the border.
Hand pierced fretwork to my own traditional-style design inspired by Victorian patterns.
Sycamore reed pans (rotated parallel-chamber arrangement with variable chamber depths).
Sycamore action boards.
Spruce bellows frames with splined corners (for lightness and strength).
Curved rippled English walnut and Ebano hand rails with leather-cushioned thumb pad.
The strap clamp screws go into threaded brass inserts (rather than directly into wood as on many vintage instruments).
Heavy duty black leather hand straps with rounded edges and skived back.
All exterior woodwork painstakingly French-polished by hand.
Traditional slotted brass end bolts with heads mostly recessed into the frame so they don’t dig into your hands or catch on the lining of the case.
21mm diameter air button hole for fast breathing.
Black mesh fabric behind the fretwork to help keep the interior clean.
I have had the opportunity to show off the instrument to several Anglo players so far and have received very positive feedback. Here are a couple of video clips of it being played (recorded on an iPhone, so not the best sound quality):
Unfortunately I didn’t get a recording at this session, but I think the player’s expression speaks for itself.
Here are some pictures of the completed Blackbird (click to enlarge):
It took me much longer than I had initially anticipated to develop the Blackbird, because after finishing my first instrument I took a fresh look at every part of the design and aspect of the build process and made improvements to virtually every component, re-made many of the special tools and jigs, developed my skills further, experimented with new materials and techniques, and as a result I believe I have succeeded in building a very nice instrument.
If you are interested in seeing many more pictures and video clips of the construction process, I urge you to dig back through the posts on my Instagram page.
At the time of writing I still have this instrument here in Burnley if you would like to contact me to arrange a visit to try it out. Better be quick though, because I have already had a few offers for it and need to sell it soon for cashflow reasons. Although this is a wooden-ended C/G, I could easily make one like it with nickel-silver ends or a different wood veneer, or in different keys (e.g. G/D), or with a Jeffries keyboard layout, or different numbers of bellows folds, or different button diameters, or with aluminium reed frames to reduce weight. The drone button is optional, or I could put other notes on it that you would find more useful. I’m happy to discuss the possibility of more significant variations like different numbers of sides, smaller frames, extra buttons, etc. I am also willing to consider building other types of concertina: the next two new instruments in my order book are both Crane duets. At this time I am focused on making bespoke high-quality English-construction instruments with my own traditional reeds.
Something important to bear in mind if you are in the market for an instrument is that as a new maker without an established reputation I am currently charging below market rate for an instrument of this quality, in order to build up experience and get my name out there. Right now my waiting list is roughly five months, but once the order book starts filling up I will reevaluate my prices.
As with the development of any prototype product, I encountered quite a few ‘unplanned learning opportunities’ along the way: My first two attempts at laminating the end boards warped badly before I managed to make a pair that stayed flat. The French polishing process went wrong several times and I had to repeatedly sand it back and try again before I was finally happy with it. Related to that, the black wool button-hole bushes look dusty as a result of repolishing the ends one final time after I had glued the bushes in. My first attempt at machining an action board went so wrong that I scrapped it and started again. I made a full set of action levers before realising I’d made a mistake in the design and they were all the wrong length. Some of the action springs were really tricky to install because I hadn’t allowed enough space for them. I somehow tuned a reed two semitones higher than the pitch engraved on the frame. I initially made one of the highest reeds an octave lower than it should have been. A mistake with the design of the hand strap clamps means you need a screwdriver to adjust the strap length. The bellows have a few minor cosmetic issues that don’t affect the playability of the instrument (in particular I experimented with a different sort of leather that has a coarse plasticky artificial grain – it works fine but I don’t like how it looks). The very highest three or four ‘dog whistle’ notes have a narrower dynamic range than the rest of the instrument (though none of the test players noticed until I pointed it out – I’ve been told most players very rarely use those notes). Probably several other things I’m forgetting right now. All stuff I learned from on this build and will be able to avoid the next time.
I am grateful to several other concertina makers who offered useful advice and ideas as I was working on this project, including and especially Chris Ghent, Geoff Crabb, Bob Tedrow, Dana Johnson, Jake Middleton-Metcalfe, and Wim Wakker. I also ‘borrowed’ a lot of ideas from studying older instruments made by Crabb, Lachenal, Jeffries, Wheatstone, and Dipper (mostly from online photograph searches, though I’ve learned a great deal from the vintage instruments I have restored).
Apologies for not posting more frequently to the blog. I am currently working on No. 2 and hope to complete it in the next month, but to tide you over here are some pictures from another complete restoration I did at the start of this year. If you would like more timely and frequent updates on my progress, feel free to follow me on Instagram.
This instrument is an unbranded 26 button Anglo. From comparison to other similar instruments, my client and I believe it was probably made by the Crabb company, and it looks almost identical to some early Jeffries branded instruments (except for the missing Jeffries stamp on the frames).
The original end plates were solid rosewood with a fairly simple fretwork pattern. Unfortunately they had cracked badly and large pieces were missing. My client had seen the earlier blog post about the new metal ends I made for the 40 button Lachenal, and asked me to do a similar job on his instrument, albeit with a Jeffries-style pattern.
The reeds were quite well made, though they had suffered a little from rust and previous inexpert attempts at tuning. The chamois gaskets were doing a very poor job of preventing leaks, mainly due to various parts of the casework having warped.
The action box sides had thick brazilian rosewood veneers, several of which had come unglued, one of which was missing.
The instrument had a moth infestation, which had eaten any of the wool parts (particularly the pads), and seemed to have had a go at the bellows too. It was still active too: I found a live larvae hiding at the bottom of one of the button peg holes!
One of the action platforms had warped so badly that it had mostly come unglued from the pad board, which had a couple of big cracks in it. It was so bad that I decided to remake the platform.
The two extra bits of wood in the bottom half of the picture are there to reinforce the cracks in the action board (I glued it back together but wanted to add a bit of extra strength).
I replaced the missing bit of veneer with a piece of Indian rosewood. Not quite the same colour as the original, but it didn’t stand out too badly after I had refinished the instrument with garnet shellac. I had to use two layers because modern commercial veneer is unfortunately much thinner than the stuff used by Victorian makers.
I made a scratch stock to replicate the decorative groove:
Action boxes cleaned up, all traces of the moths removed, loose joints reglued, and the original worn button peg holes plugged for later redrilling.
The nut plates in the bellows frames were really crudely installed, mostly very wonky and sitting proud of the surface. This later caused me a bunch of problems with getting the gaskets to seal properly.
Replacing the reed pan corner support blocks.
I used card shims under the bellows frame gaskets to get a reasonably even fit.
The bellows were pretty worn out and only five folds, so I made a new set of six-fold bellows with Jeffries papers and gold tooling. I’m not going to go into detail about these here because I spent a lot of time working on the gold tooling process and haven’t yet managed to get totally consistent results. I plan to work more on this and come back to it in the future.
I cut the end plates by hand in the traditional way. The pattern is based on a Jeffries design, but I had to redraw and modify it a bit to shift the keyboards further up and fill in the space left by removing a couple of buttons on each side.
A little method I thought up (probably not original) to put a valve restraint pin in a chamber that doesn’t have a side wall next to the valve.
Unfortunately several of the reeds had suffered a bit of damage from earlier tuning attempts – here are three of the worst examples. The moral is, don’t use a scratch tool or a coarse file for fine tuning (I recommend a 600 grit flat diamond needle file), make sure you use a steel shim under the tongue to support it and protect the brass frame from the file, and be very careful with the delicate thin tips of the higher reeds.
I refinished the casework with garnet shellac. I was pretty happy with the shine I got from the French Polishing process – I’m getting better at it with each instrument I do.
Rebuilt actions with new pads, springs, etc. I also replaced the bone buttons with solid stainless steel ones (not made by me).
The finished instrument after final polishing, etc. It sounded pretty good too!
A few weeks ago, a fellow concertina restorer contacted me to ask if I might be interested in manufacturing reproduction Wheatstone-style nickel-silver-capped buttons. As it happened, I had already been planning to develop the tooling to make this style of button for use on my own instruments.
I used solid acetal (Delrin) buttons on my own first instrument. They work fine and I expect them to last a long time if not abused, but I can’t deny that they have a ‘cheaper’ feel than metal, that isn’t really in keeping with the materials used for the rest of the instrument. As the maker, I know each button was lovingly hand-turned and polished, but a layperson could assume they were squirted out of a machine by the million like toothpaste tube caps.
Historically, cheaper instruments had bone buttons, whereas high-end instruments usually had nickel-silver (German silver) buttons. Solid nickel-silver buttons are surprisingly heavy, so manufacturers typically either drilled a hole in them and soldered a thin cap over the hole, or pressed a cap from thin sheet metal and used it to cover a lightweight core made from wood. Wheatstone later switched to making the cores from plastic because it is less prone to splitting.
My collaborator sent me a sample vintage Wheatstone button, and I started reading about press tool design. It was the first time I’ve made this sort of tool and possibly my most ambitious toolmaking challenge to date, so it took me a little while and I made a few mistakes along the way.
I did nearly all of the toolmaking on my little Taig micro lathe; it’s a surprisingly capable machine if you keep your tools sharp and stick to very light cuts.
I made the blanking punch from an 18mm silver steel bar, and the die from an O1 steel plate with a 1″ thick mild steel guide block bolted over it.
Boring out the guide block on the Taig lathe; this was a bit scary swinging such a heavy lump of steel at the lowest speed the lathe can manage:
Then I unbolted the guide block without moving the bottom plate from the chuck, and bored the hole in the die slightly larger to give the appropriate clearance between the punch and die.
Brass spacers guide the nickel silver strip through the tool.
Shearing off a strip of 0.5mm nickel silver to feed into the blanking punch.
The blanking punch produces 18mm discs. I drive it with a sharp whack with a lump hammer rather than using the press, both because it’s quicker and because a sudden shock will tend to shear the metal cleaner with less distortion than slowly pressing the punch through it.
The next tool was the cupping die, so-called because it turns the flat discs into cups. The bottom die has a recess bored into it to hold the disc perfectly centred over the hole.
After putting the disc into the die, I clamp the guide plate over it (light finger pressure is sufficient), then drive a polished silver steel punch with rounded corners down through the die with my arbor press.
This produces shallow, large-diameter cups. They are already starting to look a little bit like buttons if you squint.
Next I need to take the cups through a series of redrawing stages; each one reduces the diameter of the cup by around 20% while also increasing its depth. If you tried to go straight from a flat disc to a finished button cap in one stage, the walls would wrinkle and jam in the tool because there’s a limit to how much you can alter the shape of the part in each pass. The square parts in this photo are a mild steel tool holder, then there’s the silver steel punch, die, and guide, with an acetal spacer between the two. I later figured out that this stage works more reliably if I clamp it together very lightly with spring washers, so it’s possible for the guide to lift slightly if it has to.
The first redrawing die is a reverse die; this means you place the cup over it and the punch turns it inside out. In hindsight this probably wasn’t the best idea, but it does work. I did it because it looked easier to make, and I wasn’t aware of the drawbacks involved in reverse redrawing.
The cup comes out of the bottom of the die stuck on the end of the punch. Sometimes they can be very tight and difficult to remove. An industrial drawing press has something called a ‘stripper’ that holds onto the part while the press yanks the punch back up through the die with a lot of force, but with my low-tech tools I have to resort to manually knocking them off using a bar with a hole in it.
The rest of the redrawing dies are direct dies; i.e. you place the cup into a large section at the top of the die, then the punch forces the cup through a narrower neck with a rounded corner at the top.
Pushing the punch through the die with my Jones & Shipman arbor press. I was a little concerned before starting the project that it might not prove strong enough for the task, but in fact it is quite capable of bursting open the top of the cup if it gets stuck in the die.
A successful second redrawing.
The two diameters inside the top of the die need reaming with a purpose-made D-bit. By making a single tool that reams both diameters at once, it was also able to form the rounded transition at the top of the neck (this is a very important feature of the die because the metal won’t flow smoothly around a sharp corner).
The inside of the final redrawing die, after reaming with the above tool. Of course I also had to polish it smooth after hardening it to keep the friction as low as possible. You can’t see it in this picture, but the neck is quite short, with a slightly larger diameter section below it.
I found it wasn’t necessary to clamp the guide block down on the last redrawing tool:
Here’s the full sequence of parts produced by the above stages. The blank disc is 18mm diameter, and the final cap is about 5.8mm diameter by 15mm deep:
I encountered quite a few problems along the way; in particular I found that the parts often jammed in the die and burst because the bottom edge of the cup had become thickened. In theory you can work around that by increasing the clearance between the punch and the die, but I found that caused other problems, so before the second and third redrawings I instead manually grind a little bit of thickness off the lip of the cup, just enough to allow it to go smoothly through the die.
I found that I got better results if I annealed the cups between stages. It probably isn’t strictly necessary to anneal every time, but it did seem to help them draw more smoothly with less force. In my initial experiments I annealed them with a blowtorch, which works OK but takes a while and uses a lot of gas if you’re making lots of them.
I next tried putting them in my electric heat treatment oven.
This did a nice consistent job of annealing them, but because they were exposed to the oxygen in the oven for a long time, they built up quite a lot of scale that caused so much extra friction inside the die that I had to spend ages polishing it off before they would redraw smoothly.
Next I tried putting them in the electric oven inside a tin with a little hole in the lid.
The buttons were coated with grease used to lubricate the drawing process; as this burnt off, it displaced the oxygen inside the tin and generated a little flame at the vent hole:
Much better. They came out of the tin a little sooty and discoloured, but nice and soft with no significant scale buildup. I cooked them at 450°C for an hour, which is probably overkill but didn’t do any harm. I will experiment with reducing the time when I do the next batch.
After the final redrawing stage, the caps were approximately the right diameter but a bit lumpy and too long. To cure this, first I mounted each cap on a tapered wooden mandrel on the lathe and used a wide flat fine file to smooth them out:
A quick polish brought out a nice shine:
I made a special soft collet to hold the buttons bottom-out in the lathe while I parted them to length. Incidentally, those random frilly edges are very typical of drawn sheet metal parts and are called ‘ears’.
There is a depth stop inside the collet, so I was able to lock the lathe carriage in place and quickly part off all the caps to the same length.
With the metal caps finished, I now needed to make the acetal cores. They are almost identical to the solid acetal buttons I made for the first instrument, apart from not bothering to give them a nicely-domed head or polish them.
1. Extend an appropriate length of ¼” black acetal from a collet.
2. Face off (only necessary on the first button from a new piece of stock).
3. Turn down to the right diameter to fit inside a cap. This is trickier than you might think because the acetal is very bendy and wants to deflect away from the cutting tool, particularly at the end furthest from the collet. It helps to use a razor sharp tool and cut to the final diameter in a single pass at quite a slow feed rate. Even so I had to experiment quite a bit before I was reliably producing cores that fit nicely.
4. Roughly round over the corner with a file. This doesn’t need to be pretty because it won’t be seen, but it is needed to allow the core to go all the way into the cap, because the inside of the cap is slightly rounded.
5. Part off to roughly the right length.
6. Put the core in another specially-made collet with a depth stop in it, with the bottom end facing out.
7. Face to exact length. Note that I have the carriage stop set to allow me to repeatably turn up to the transition between the pin and the main body of the core, so for this stage I clamp a spacer between the stop and the carriage that is the same thickness as the length of the pin.
8. Turn the pin to diameter in one pass. If you look closely you will see I ground a flat on the corner of the lathe tool in order to form a fillet at the root of the pin; this greatly reduces the likelihood of the pin breaking off if the button gets knocked hard.
9. Chamfer the point of the pin with a file.
Next we have to drill the cross hole and countersink both sides. The original Wheatstone core had a 2.5mm hole, but I find that 3mm holes work better with modern 0.85mm bushing cloth. To avoid needing to spot each hole with a centre drill, I instead got a 3mm twist drill and ground it as short as possible to make it very rigid so it doesn’t deflect and drill the hole off-centre.
This is the same fixture I used to hold the buttons I made for my first instrument, but I have modified it a bit and I’m now doing both the drilling and countersinking on my CNC milling machine instead of the manual drill press. Firstly because the mill is more rigid and accurate, secondly because it has a quick change toolholder that lets me swap between tools and know the tip of the tool will be the same distance from the spindle nose each time, and thirdly because I was able to write three very simple macros that repeatably perform exactly the same operations each time without relying on manual depth stops.
The pins in the mounting board correspond with the holes in the fixture and allow me to turn the button 180° to countersink the opposite side of the hole. The fixture is actually inaccurate by about 0.3mm, but because the error is the same every time I was able to program the machine to compensate for it and get the second countersink to line up pretty much perfectly (this wasn’t the case with the manual drill press, leading to the countersinks all turning out a tiny bit misaligned; probably not enough to significantly effect the operation of the action but enough to annoy the perfectionist in me!).
The countersinking bit. It has a 10mm shank and all my quick change toolholders are imperial sizes, so I had to turn a special adapter sleeve to avoid having to hold it in the drill chuck, which would have caused problems with the tool Z offset changing every time I swapped back and forth between the drill and the countersink.
A finished button core. With a little polishing, this would be perfectly acceptable as a solid acetal button.
I made a special tool to crimp the caps onto the cores. The Wheatstone sample had a single small dot, presumably made by something like a centre punch, but in my experiments I found that if I instead made a punch with a slightly blunt chisel-shaped tip, it takes several times the amount of force to pry the caps off.
A quick final polish on the buffing wheel:
Followed by buffing with a soft cloth to remove the polish residue:
Here is one of my buttons next to the Wheatstone sample. The main difference is the increase in the diameter of the cross hole:
And here is my full first batch of buttons (I would have made more but I ran out of materials):
Here is the full lineup of tooling I made for this process:
This has proved to be quite a challenging project at times, and as always there are things I would make slightly differently if I knew then what I know now, but I am very pleased with the high quality of the resulting buttons and I’m looking forward to building an instrument that includes them.
Some future experiments:
Materials. I’m pretty sure this tooling would work with other non-ferrous metals. I have read that a fairly high percentage of the population is sensitive to nickel and might not be able to comfortably use an instrument with nickel-silver buttons. Alternatives include copper, various alloys of brass/bronze (some of which are more tarnish-resistant than others), or a silver alloy like sterling silver or Argentium. Aluminium could work but may be a bit soft and prone to oxidation. Titanium would be interesting but I’ve not yet worked with it and don’t know much about how easy it is to press. I’m not sure how well the tooling would cope with stainless steel, as it’s much harder.
Diameter. English-made concertina buttons have been made in a variety of sizes between about 4.5mm and 6.5mm (German-made ones were sometimes even larger). Preferred diameter comes down to each player’s fingers and playing style, though there are practical limitations too (e.g. there may not be room in a very dense action for large-diameter buttons). The most common size for English-system instruments seems to have been 3/16″, or about 4.75mm. I don’t think it’s a coincidence that the cores of the buttons I’ve just made are also approximately 3/16″, which gives a cap diameter of about 5.7mm. It would be interesting in the future to try making another final redrawing tool that produces 3/16″ caps, and possibly yet another one to produce 1/4″ (6.35mm) caps.
Tip shape. Another aspect of button design is the shape of the tip. From discussing this with players, it seems that some prefer very flat-topped buttons, others very rounded, and yet others are happy with a compromise somewhere in-between, with a very slightly convex top and more rounded corners, as in the caps I have just made. I think it would be fairly easy to make the caps more rounded by making a new final punch with the same diameter but a hemispherical tip. Making caps with a flatter top would be slightly trickier, because if the punch is too flat it causes a concentration of force at the corner which tends to burst the cap in the die. The answer might be to make the caps slightly rounded as above, then use a different tool that compresses the cap between a flat punch and a flat anvil (or perhaps the punch might even need to be slightly concave). More experimentation required.
Length. Not exactly an experiment, but just to point out that because I’m turning the cores manually and the caps come out of the press several mm longer than necessary, it would be trivial for me to make buttons that are up to about 4mm longer or shorter for different depths of action box/thickness of end plate, or for a player who prefers buttons that are extra long or extra short. I can also alter parameters like the length and diameter of the pin and the location of the cross hole if necessary.
I recently fully-restored a 40-button Lachenal Anglo. It was in pretty poor condition when I received it. The wooden ends were non-original, damaged, and not very well made.
The bellows may have been original, but they were worn-out and patched.
There was significant damage to the woodwork, including a couple of split reed chamber walls.
The pads were mostly dust held together with blobs of sealing wax, and the springs were mostly non-original and much too strong, probably in a vain attempt to make the knackered pads seal.
Step 1: remove the old bellows.
The bellows frames weren’t too bad underneath, apart from a few loose/missing corner blocks.
Next I dismantled the actions, laying the levers out on a piece of card so I could figure out which was which when it came time to reassemble the instrument. Quite a few of the action box walls had come apart at the glue joints, but the wood wasn’t too damaged.
Most of the end bolts and corresponding nut plates were worn out, probably due to somebody over-tightening them in an attempt to make the instrument airtight (unsuccessfully, because the various boards had all warped).
I already wrote an earlier blog post about making the new end bolts. I also made and fitted a new set of nut plates from thicker brass (3mm rather than 2mm), so they will hopefully be less prone to stripping in the future. The new wood screws are stainless steel and slightly longer than the originals. I plugged up the old screw holes with matchsticks before fitting the new screws.
The end bolt holes in the action box walls were worn oversized (particularly at the tops, where the screw heads had sunk through the end plates and worn a deep gouge), so I plugged them all with beech dowels.
I glued the walls back together in a band clamp using hot hide glue. Unfortunately the top and bottom halves didn’t quite match up perfectly, which I later realised must be because they originally came from different instruments (they are a different wood, and the pad gouges on the inside of the top walls don’t marry up with the positions of the pads).
I used a simple jig to re-drill the end bolt holes a consistent distance from the outside of the instrument.
Then I clamped the bellows frame to the bottom half of the action box and drilled the tapping holes in the nut plates.
Once I’d got a couple of them drilled, I used spare drill bits to keep them aligned to each other while I drilled the other four.
I took the plates off again to tap them, to avoid embedding a lot of greasy swarf inside the bellows frames for perpetuity.
As I mentioned previously, two of the reed chamber walls had split. I could have attempted to glue them back together but I doubt it would have held up for long, so I unglued them (hot water to soften the hide glue, and waggling until it suddenly came free like a loose tooth).
I glued new quartersawn sycamore walls in place, with hide glue again, using the reed as a wedge to hold it in place while the glue dried.
One reason why this wall was weak was that part of it needs to be cut away to make space for the valve in the next-door chamber. I thought it best to chisel this out in-situ.
I used a combination of needle file and skew chisel to undercut the new wall for the dovetailed reed slots.
Both the action boards were badly warped, so they didn’t seal properly to the tops of the reed pan walls. I cured this by painstakingly lapping them using a sheet of sandpaper glued to glass. I don’t seem to have a picture of it, but I also inlaid a piece of sycamore to repair the deep gouge visible in this one where the sound post screw goes through it.
On the right hand reed pan, it was so hollow near the sound post screw hole that I decided to glue a piece of veneer to the area to build up the thickness before lapping most of it away. This incidentally also filled in the oversized gouge around the screw hole.
The reed pans were warped too, though sadly not in a way that matched the warping of the action boards, so I also had to lap the tops of the walls. To avoid removing too much depth from the chambers, I had to glue tapered shims to the tops of about half of the walls near the outer edge.
After getting the tops of the reed pans flat, I replaced all the support blocks in the bellows frames. This is far easier to do without the bellows in the way, hence why I did all the above work prior to making the new bellows.
This shows why you sometimes find a block or two that isn’t right in the corner of the bellows frame.
The woodwork repairs done, I made and fitted new chamois leather gaskets. Not pictured, it was necessary to fit card shims to the inside of the bellows frames before the chamois to get the pans to fit tightly.
I have recently bought an old picture framing mat board cutter. This tool makes it much easier to cut the bellows card into strips, bevel the top edges at 45°, and with a simple jig, cut the strips into individual cards. Incidentally I switched from 1.5mm thick greyboard to 1mm thick millboard. It is a little more flexible but the reduced thickness really makes the bellows feel a lot less bulky. I think it’s a better quality material too, and likely to last longer.
After my experiment with self-adhesive hinge linen on the last set of bellows, I went back to Fraynot linen cut on the bias, attached with a bookbinders’ starch paste. The resulting hinges are thinner and much more supple.
Because I originally made my bellows mould to fit a set of bellows that came off a 6″ instrument, and this was a 6 ¼” instrument, I had to pack them out a little using strips of thin plywood between the core and the forms.
This time I prepared all of the leather parts before starting to glue them on. I also refined the shape of the gussets a little, and skived most of the parts slightly thinner than on previous bellows.
The bellows immediately after taking them off the mould! They are initially quite stiff and need to be broken in. In order to maximise their useful range, I spent the next few weeks while I was working on other parts of the restoration alternating between squeezing them fully closed in my bellows press and stretching them fully open using a couple of the forms from the bellows mould, exercising them a bit every time I handled them. I think this treatment along with other improvements really helped; the finished bellows are the most supple I have made to date.
A set of reproduction Lachenal bellows papers really helped them to look the part.
I recently bought a small Eclipse fretsaw frame that is the ideal size for concertina ends; much less tiring to use than a standard large fretsaw frame. I had to make new blade clamps because the old ones had stripped threads. I made the new clamps from scraps of tool steel and hardened them, so they ought to last pretty much forever now! I also made a new saw table with a nice big flat rigid top.
This shows why I made the top of the saw table so high; I prefer to do piercing standing up, and this height results in my arms being in the most comfortable position.
I cut the new ends from 22 S.W.G nickel silver (German silver) sheet, starting by roughly cutting them out oversize with a slitting blade in an angle grinder.
The fretwork design is based on photos I found online of a vintage Lachenal 40-button, but I redrew it and modified it a little (eliminating the redundant unused button holes on the opposite side from the thumb button on each side).
I drilled all the holes first. The bolt holes are actually transferred from the action box frames, not the template. I later realised the button holes should have been a bit larger to give more clearance around the buttons, so I had to enlarge them after I had cut all the fretwork.
Piercing in progress. I actually find this one of my favourite parts of the job; my mind goes into a flow state, and when I emerge some hours later I have made a beautiful thing.
I’m going to skip over a few days of toolmaking here; I may come back later and write a separate post about it. I made a press tool modelled on the one used by the Crabb company, which crimps the edges of a metal end plate one side at a time.
The side on the left has been crimped, the tool is about to press the side in the middle:
The end result. I found I had to do some manual cleanup work to neaten it where it hadn’t worked perfectly, particularly in places where the piercings were quite close to the border.
I polished the finished ends using my Bridek polishing spindle and various Menzerna compounds.
The button peg holes in the action boards were both worn oversize, and probably no longer exactly aligned with the button holes in the new ends, so I decided to plug them all with beech dowels and re-drill them.
I made this tool to drill the button peg holes; the brass bush is the right size to slide in the button hole and guide the drill bit to the right location in the action board. I used the depth stop on my drilling machine to make sure I didn’t quite drill all the way through the board.
You can see in this one that the new holes are sometimes slightly off from where the old ones were; if I hadn’t re-drilled them, the buttons wouldn’t have lined up right, which would probably have caused them to stick.
In order to bush the button holes, I needed to screw a piece of plywood to the underside of the end plate so I could glue the bushes into that rather than trying to glue them directly to the thin metal. (I later cut the board to match the fretwork.)
A different special tool used to accurately locate the pilot holes in the bushing board.
I fitted loudspeaker grille cloth below the fretwork. It proved a bit tricky to get the button holes in the right places; I settled on making a card template, then placing the template over the fabric, cutting around it with a rotary cutter, and punching the holes through the card and fabric both.
I glued the fabric to the underside of the metal with PVA (rather a fiddly job to avoid baggy areas or holes not lining up). One side-effect of this was that the acidic fumes given off by the glue oxidised the polished surface of the metal, and of course I couldn’t just take them back to the polishing machine because it would probably damage the cloth. I managed to clean it off with dry jewellery polishing pads but it was a bit annoying. Perhaps epoxy would be a better choice.
I laser-printed a replacement maker’s logo on archival paper and stuck it on with PVA.
This is a taper reamer I made from silver steel to slightly taper the holes in the bushing boards. By making the holes looser at the bottom than the top, they are better able to cope with any slight misalignment than if the sides of the holes were parallel.
Similarly, I made a new bushing reamer that is continuously tapered, thus making the bushes looser at the bottom. You can also see in this picture that I cut the boards closely to the outline of the fretwork and coloured the edges black so you can’t see them under the grille cloth.
Lachenal action levers sometimes wear in a way that causes them to twist as they pivot, causing uneven movement and pads not seating properly. The way I fix this is by building up silver (hard) solder on the worn area of the lever, then filing it back until it fits well again. Usually the post isn’t badly worn enough to need the same treatment. I had to do this repair to about half a dozen of the levers on this instrument.
Cleaned and rebuilt actions, with new springs, bushes, dampers, pads, etc.:
My first attempt at the elongated air hole pad was to cut it from the same leather/felt/card sandwich as the ordinary pads. It sort of sealed, but would leak when you pressed the bellows hard. I worked out that it was because the card was too flexible; the ends of the pad were flexing up and letting air leak out. I fixed this problem by making a special pad with a top layer made from thin stainless steel sheet instead of card.
Skipping over a bunch of toolmaking again; I made a set of dies to punch my own valves to a consistent range of sizes. I also got hold of some special thicker (very expensive) leather that is better-suited for the largest valves. I made the new valve restraint pins from 24 S.W.G. stainless steel spring wire. I have switched to using gum arabic to glue the valves to the reed pans; it is plenty strong enough when dry, easy to use and non-messy, and very easily removed with a little warm water on a cotton bud when you need to replace a problematic valve. I lightly cleaned all the reeds, and where necessary shimmed the slots in the reed pan to get the reeds to fit snugly.
The strap-adjuster thumb screws were the wrong ones for the instrument; the thread didn’t fit the captive nuts. To cut a long story short, I decided to make all new nuts and screws with an M3 thread.
Luckily I was able to reuse the tiny wood screws; finding replacements for them might have been tricky.
I’m quite proud of these thumb screws; it may seem like a trivial detail but the first ones I made were pretty bad in comparison, and I really think I have got the hang of them now. If you dig back through my Instagram page, somewhere in there is a post describing my process.
There’s quite a bit going on in these next two pictures. Firstly, notice the bottom half of the wall is ebony (original to this instrument), the middle section is mahogany (probably came from a different vintage instrument), and then there’s what appears to be another ebony section between the mahogany and the metal plate. I needed to add the second black section as a spacer to make the boxes a bit deeper, because the action levers were hitting the bushing boards. It is made from a manufactured ebony substitute called Rocklite Ebano. Although I needed to do this for mechanical reasons, I actually think the three-layer effect looks quite unique and attractive.
Secondly, I sanded and lightly French-polished the woodwork. I deliberately didn’t go overboard building up a high gloss, and I tried not to remove too much of the old patina in the process.
Thirdly, I made new brass strap rings (the loop thing that holds the strap down to the thumb rest), replaced the captive nuts in the ends of the handles with M3 ones, and made domed brass washers to hold the fixed end of the straps.
Fourthly, I made new leather hand straps. I don’t think I’ve quite got the pattern perfect yet (the ‘tails’ are about an inch too long), but I have figured out how to round and smooth the edges using an edge beveler and a burnishing spindle so they feel more comfortable on the hands.
When I received the instrument it was in C#/G#, old philharmonic pitch, which is about half a semitone higher than modern concert pitch. In consultation with the client, we decided I would re-tune it up to D/A concert pitch. Actually, I later realised that it may have originally started out as D/A old pitch and been tuned down to C#/G#, because the note stamps on the frames made more sense if that was the case. Most of the reed tongues were steel but there were a handful of brass ones in there too; you have to be very gentle with them as a tiny amount of filing can cause a big shift in the pitch, much more so than with steel ones.
The highest reed on the instrument was missing. I worked out from button charts that it was supposed to be a very high F#. I made a replacement, making an educated guess as to the length of the vent. It was so small that I didn’t have an end mill that could cut the vent slot so I did it by hand with a jeweller’s saw and tiny files (not as difficult as it sounds, though a little time-consuming to get it perfect). After experimenting with the profiling for a while, I managed to get it sounding remarkably well on the tuning bellows. Unfortunately once in the instrument, this reed, along with the other three or four highest notes, were pretty unresponsive, needing quite a high bellows pressure to get them to start. After quite a long time spent experimenting with them, I came to the conclusion that the problems mostly came down to the reed chambers being too large.
The worst one would barely speak at all (the one on the bottom side of this chamber; it is quite a lot higher in pitch than the corresponding top-side reed). I managed to significantly improve it by replacing the end wall with one closer to the vent slot so as to reduce the chamber volume.
My highest reed was in an inboard chamber. I managed to improve its response by making a little removable block that significantly reduces the dead volume in the chamber.
The finishing touch was to add my mark to one of the reed pans.
I had one or two bits left over after I finished putting it back together!
The finished instrument (photo courtesy of the instrument’s owner, Wallace Calvert). I am particularly proud of how nicely the new end plates turned out.
And now for a special treat, here is a clip of Wallace playing The Humours of Tullycrine on the instrument:
On my first instrument, the ends were held on with commercially-made stainless steel allen-head M3 screws. They work fine, but I felt they gave the instrument a bit of a modern, almost industrial look.
I am currently working on restoring a vintage Lachenal Anglo for a client, and the end bolts and captive nuts are missing or badly worn due to past over-tightening (probably from trying to cure leaks that were actually due to internal structural problems). Needless to say, it wouldn’t have been appropriate to replace them with modern screws. Rather than try to source a better second hand set from a parts dealer, I decided it was time to figure out how to make my own new brass end bolts from scratch.
I sourced some 4.5mm diameter free-machining brass bar. The finished heads want to end up about 4.5mm, so I need to avoid turning it any smaller in the process. It came in 330mm lengths, which I figured out would comfortably make eight bolts if I cut it into four sections.
One bit ended up too short due to a mistake. Incidentally I used to think junior hacksaws were rubbish until I got some better quality Sheffield-made blades and found this excellent frame for a pound at a car boot sale. It tensions the blade really tight, which prevents it flexing in the cut, and the aluminium handle is really comfortable.
If I’d only been making a small number of them I probably would have held the blanks in the three jaw scroll chuck and accepted that they would turn out slightly non-concentric, but since I needed to make a large batch and will be making more in the future, I decided I wanted to use a collet instead. Taig (the manufacturer of my lathe) sells a few standard imperial-size collets, and blanks that you can drill to whatever size you want. I’ve had this lathe for probably fifteen years and this is the first time I have ever used one of the blank collets! They are made from a nice free-machining steel that drills very easily:
The difficult part is holding the awkwardly-shaped piece of metal while you cut the slots in it. I settled on putting a piece of the 4.5mm brass in it, and holding that in the vice instead of the collet.
Once I had sawn the first slot, I turned it 90° and used the slot in the brass bar to guide the saw while I cut the second slot. Then I flipped it over and cut the other two slots.
The finished collet. Not too bad for a junior hacksaw.
The first step in machining the bolts was to put the blank in the collet with enough protruding for a single bolt, then turn down the shaft to 2.25mm. Before doing the job, I spent a long time worrying about how I would do this without the shaft flexing away from the tool towards the end, resulting in it getting fatter towards the tip. This wasn’t as much of a problem as I expected it to be. Getting the tool bit really sharp and running the lathe at its maximum speed was a good starting point.
The first method I found was to turn the first third of the shaft to finished diameter a bit at a time, then move along and turn the second two thirds to finished diameter. This worked fine but took a couple of minutes per bolt. I found I could take heavier cuts on the second section, then I got to experimenting to see how far I could push it, and to cut a long story short, it turns out that it’s perfectly possible to turn the entire thing to finished diameter in one pass! Once I figured this out, it sped things up quite a lot. It’s important that you do it in one pass, because you need the full diameter of the bar to the left of the tool to support the cut. If you try to do a second cleanup pass, however light, the bar will flex at the end. Here’s a video clip to prove it:
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Next I used a fine single-cut file to put a blunt point on the shaft.
Then I used a tailstock die-holder and a good quality sharp HSS die to cut the threads. I used a dab of cutting oil (it really makes a noticeable difference to how easily the die cuts) and turned the spindle by pulling on the drive belt, using a ruler to measure when the tailstock had moved far enough for the desired length of thread. The video above also shows the thread cutting operation.
A brief digression about the threads: the original Lachenal bolts are about 2.25mm major diameter, but a relatively coarse pitch. I haven’t been able to find any standard thread that matches it. Since I don’t have a screw-cutting lathe, to copy it I would have had to commission a specially made tap and die set, which would have been very expensive. I instead decided to use 8BA, which has the same diameter but a finer pitch. I don’t think this is a problem for the restoration because I am replacing all the bolts and captive nuts at the same time. From what I have read, the Crabb company used 8BA bolts in their instruments too. BA threads are mostly obsolete now apart from a few niche applications, but you can still get hold of new taps and dies for them.
After doing all the above steps to one end of the blank, I turned it around and did the same to the other end. I probably could have used slightly shorter blanks, it just worked out this way when I cut the bar stock into four.
Next I needed to cut the piece into two and form the domed heads. To do this efficiently I got a ¼” HSS tool blank and ground a special profile onto it. This profile first parts off the stock to length, then you carry on plunging it and it forms the domed shape.
Here’s a video of the process showing how quick it is:
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Next I cut the slot in the head using a HSS slitting saw, 50mm diameter by 0.6mm thick with 100 teeth. I didn’t have a mandrel with the right centre diameter, but Taig sells blank mandrels that screw onto the headstock so you can turn a custom spigot to fit your saw blade. Luckily I have an older-model Taig milling machine that has the same headstock on it as my lathe; newer mills come with an ER16 collet chuck instead, which makes this sort of thing a bit more complicated because you can’t just transfer something straight from the lathe headstock to the mill.
A nice snug fit on the mandrel:
Next, I needed to make a special fixture to hold the bolts on the milling machine while cutting the head slot. I made the top part from aluminium, and the nut bar from mild steel. Tightening the set screw clamps the shaft of the bolt tightly.
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Although I did it with a short hand-written CNC program because I have a CNC mill, this operation would be dead easy on a manual mill or even a milling attachment on the lathe. I found that with the CNC mill, I could load a bolt in, hit Start, go back to the lathe, turn the head on the next bolt, and return to the milling machine around the time it finished cutting the slot.
Next I put the bolt back in the lathe and used 800 grit emery paper and the top speed to smooth out any tool marks and burrs.
Finally to the polishing spindle to give the head a shiny finish. This Menzerna 480W compound is very effective on brass.
I had to use a screwdriver to clean excess polishing compound out of the slot of each one.
Here’s the first one I made between a couple of different ones from the vintage Lachenal. My head is more closely based on the shallower one on the right.
I made a batch of about seventy bolts; enough for the Lachenal restoration and my next few instruments.