alex_holden

I'd forgotten about that post. Last year I turned a set in stainless steel, which was much harder to work with than free-turning brass (my client wanted silver-coloured traditional slotted heads, but didn't want nickel due to an allergy). Coincidentally I will need to turn up a fresh batch of brass bolts soon. Maybe I will try making one of Theo's hollow cutters first. I ran into several problems making the tap, mainly due to limitations of my lathe, and after some unsuccessful attempts I put the idea on the back burner thinking I might try again if I ever upgrade to a better lathe. To be honest I'm happy enough with 8BA, and you can still buy taps and dies for it. The closest metric thread is M2.2x0.45. The only reason you might want to use the traditional 'concertina thread' on a new instrument is that it is a very coarse pitch so you don't need to turn the screwdriver as many times to remove the ends.

I think the image came from a previous topic where somebody was discussing a bass G/D layout. The instrument in this thread doesn't sound like a bass to me.

Yes, that's right. Incidentally Whitworth thread and its descendents (BSF, BSP etc) also have a rounded form.

As I understand it the BA standard was based on the Swiss Thury standard, which was in turn based on a study of various non-standardised threads in use at the time by Swiss watch makers. Louis Lachenal was a Swiss watch maker before he came to England. An important feature of this family of thread forms is the rounded crest and root, which reduces stress risers. I think it is fair to describe the 'concertina thread' as having a form like BA, approximately the same major diameter as 8BA, and approximately the same pitch as 5BA. That doesn't mean it is a BA thread. A complicating factor is that there are slight differences between the various manufacturers which make them incompatible with each other. e.g. a die for Jeffries end bolts probably won't make bolts suitable for Wheatstone nut plates. A few years ago I tried to commission a specialist firm to make a tap and die set to replicate Wheatstone threads. They were quite difficult to deal with and quoted me an astonishing price (I suspect they simply didn't want to take the job). I also briefly experimented with making my own tap but was much less successful than Adrian. @4to5to6: you don't need/want an acetylene torch to harden tool steel. A propane torch and a few fire bricks arranged around the part gets plenty hot enough for hardening. You want to heat it gently and sustain the temperature for a while so it has time for the molecules to rearrange all the way through, but don't overheat it because that causes large crystals to form. You can temper it either with a low flame and watching the colours, or you can do it in a conventional kitchen oven if you trust the thermostat (I've also used a deep fat fryer!). I also have a proper temperature-controlled electric heat-treating oven but rarely use it because it's a bit of a faff to set up and takes a while to get up to temperature.

There seem to be two major styles of concertina music in South Africa, played on very different instruments. This style (Zulu?) is based on cheap 20 button German concertinas, but tuned in an unusual way. David Jenkins performs and makes new concertinas of this type: https://www.davidjenkins.co.za/concertina/ The other major style (boeremusiek?) is based on a 40 button Wheatstone C/G: It's possible to find vintage concertinas of this type, or you may be able to commission a new one.

I would guess that's the most likely reason it has them. The ability to tune them differently in non-equal temperaments is an incidental benefit.

We're reaching the limits of my tuning theory knowledge so I may be wrong, however I'll have a go... The reason temperaments were invented is that Just (Pure) Intonation on a fixed tuning instrument only really works for one key. Tempering the tuning means making the intervals less pure in a way that allows multiple keys to sound acceptable. There are lots of different temperament schemes. Equal temperament is the most popular today; the idea is that the intervals are all the same size and it sounds equally good/bad in every key. The main drawback of ET is that thirds are quite impure. Other temperaments make different compromises. I think the idea of meantone is that it sounds equally good in several keys, until you reach the wolf interval, at which point it sounds horrible. Making an instrument with more than 12 intervals in an octave increases the number of keys you can play before you run into the wolf. There are other temperaments (e.g. Well Temperament) that don't have a wolf interval, so you can play in any key, but each key has a different 'flavour', some of them sounding sweeter than ET and others more dissonant. You're right that modern ECs are almost always tuned to ET because most other instruments are also tuned in ET by default, it's the simplest and easiest option if you're using an electronic tuner, and modern listeners are used to how it sounds and generally aren't bothered by the impure thirds. I'm not sure any of that was true back when the EC was first invented.

Indeed. I have noticed a significant uptick in sales inquiries in the past six months or so (and my waiting list is not getting any shorter). I believe the shortage is currently worst for Duets; at least there is a handful of Anglo makers, and in my experience there isn't much demand for new English concertinas.

It comes down to the fact that there are 14 buttons per octave rather than 12. Basically you can use a non-equal temperament if you are able to tune Ab and G# differently, and the same with Eb and D#.

They were bored out and capped to reduce their weight, and probably also because they could make the caps from tiny discs of thin silver sheet without the expense of making the entire button from solid silver. The caps are only soft-soldered on and it's quite common for them to fall off.

The reeds in the photo look like steel to me. If it's consistently only a couple of cents out it might have been tuned at some point in the past few decades. The pads look original, and could be due for replacement. The two damaged buttons in the first photo can be repaired by a reasonably skilled metalworker (e.g. a jewellery maker), by soldering new silver tops onto them.

The document attached to this comment may be useful:

I believe the reeds were salvaged from accordions, making it a hybrid IMHO.

I'm a bit surprised they went to the trouble of giving it metal-capped buttons and slotted brass action posts (expensive to make and typically signs of a better-quality instrument), but didn't fit any button cross-hole bushes (even a cheap bone-button Lachenal has those).