Why Are Concertinas Hexagonal?

[rob carr]

I expect concertina ends were intended to be round originally, but as most of the bellows makers were also leather bookbinders it must have been easier for them to work in hexagonal shapes than making expanding round tunnels. So a compromise was found that would work with the reed layouts being set around in cheese segments which must have evolved as the best acoustic solution at the time.

 

Nothing to stop them being circular now with modern manufacturing . But who would buy one? A hybrid round one would be slated so much by us traditionalists you could only play it in secret.

[Dan Worrall]

Dunno the answer to the question, but I do know that the Germans were into all sorts of end shapes by the time of this picture, from 1855. Round, square, rectangle, hex, octagon....whatever anyone wanted.

[RAc]

.

Edited March 4, 2016 by RAc

[Chris Ghent]

Geoff Crabb has made a lovely concertina with 16 sides; as I recall it has facets but no gussets.

[rob carr]

When I said modern manufacturing, I was not thinking leather. There must be some type of airtight material that can replace the leather, something along the lines of an artificial rubber compound and carbon fibre 'walls' already moulded in. More than likely something on the space station already flexing away for eternity. Everlasting bellows! I should patent that.

[Jack Campin]

Surely the apparent hexagonality is because you're looking along a diagonal at a four-dimensional cubical concertina. Which explains

 

(1) why they cost so much

 

and

 

(2) how the cat gets inside.

[Terry McGee]

Why hexagonal? Because 360 divided by 7 is 51.428571428571428571428571428571º?

Edited August 28, 2014 by Terry McGee

[Chris Ghent]

Oh, way too technical; it is so they won't get lost..!

[JimLucas]

Hexagonal is just the most organic shape, I beelieve.

[Terry McGee]

When I said modern manufacturing, I was not thinking leather. There must be some type of airtight material that can replace the leather, something along the lines of an artificial rubber compound and carbon fibre 'walls' already moulded in. More than likely something on the space station already flexing away for eternity. Everlasting bellows! I should patent that.

 

10 metre lengths enough?

[JimLucas]

When I said modern manufacturing, I was not thinking leather. There must be some type of airtight material that can replace the leather, something along the lines of an artificial rubber compound and carbon fibre 'walls' already moulded in. More than likely something on the space station already flexing away for eternity. Everlasting bellows! I should patent that.

 

10 metre lengths enough?

 

I hope that's not quite what rob was trying to describe. My experience with those "worms" is that they're like springs. If I push one "closed", I can't relax. I have to keep pressing just to keep it there.

 

I can imagine having some difficulty stopping a note (or chord) by simply holding the bellows steady at partly closed rather than by letting up on the button(s). Vibrato, instead?

 

(To remove any doubt, I'm not being entirely serious with the above, but I'm not entirely joking, either.)

[Terry McGee]

Heh heh, I was teasing a bit, but there might be some possibilities in that general approach. Some of my dust extraction tubing is similar to the above, except that the skin is not poly but a sort of plasticised fabric. It's much more free, and doesn't exhibit the springiness you mention. Indeed, it might suffer the opposite problem - when you suddenly change direction (eg in the case of an Anglo) it would spend an excessive amount of time and motion in reaching pressure again, as the fabric balloons.

 

I wonder if anyone has ever employed a spiral for a bellows?

 

Terry

[Alan Day]

We discussed in the past the possibilities of "Plastic Blow Moulding" the bellows .There are modern plastics which would stand the requirements of concertina bellows.In fact the ends were thought to be part of the moulding.Not necessarily cheap and nasty if the right plastic was used.

Al

[Geoffrey Crabb]

Well, a lot could be written in reply to some of the content within these posts but returning to the original simple query and I hope a simple answer will suffice.

Have look at this

 

Geoffrey

[Anglo-Irishman]

Hmmm!

 

As has been stated, a hexagon, or - if you've got a bit more time or money to spend on it, an octogon - is an approximation to a circle, only easier to make bellows for (in the days before those springy plastic tubes).

 

On the other hand, a hexagon is just a single step of development away from a rectangle.

 

The Germans, who originally built their concertinas rectangular, soon twigged that the Anglo-German, with its hex ends, just looked more classy, and began building their concertinas hexagonal, too. Mind you, they left the innards as they were, with the buttons, levers and reed-chambers forming a rectangle inside. I suppose that's why the early 20-button Germans had the button rows parallel to a straight side - they utilised the oblong within the hexagon!

 

So my thesis is: A hexagonal wooden box is almost as easy to build as a rectangular one, but just looks so much cooler, more expensive. Octagonal is even cooler, 12-sided even more so, and more expensive looking - thus a good status symbol!

 

Then I remembered a visit to the Grinan of Ailish, a well-preserved Celtic fortification on a hilltop in Donegal, Ireland. This structure is completely circular, and consists of a thick, dry-stone wall. The archaeologists point out that (in pre-artillery days) the circle is the perfect shape for a fortification, because it encloses the maximum space with the shortest perimiter. So the number of men you needed to defend the wall (or to build it in the first place) could live comfortably with their families inside the fort.

 

The idea of maximum area with minimum circumference also applies to the concertina. On one hand, we need as much air as we can get in the bellows, but on the other hand, we want as little mass as possible in the ends, so that we can reverse the bellows direction easily. The greater the area of the bellows cross-section, the more air we have for a given number of folds; and the shorter the frames of the action-box and bellows, the less mass we have to shove in and out.

 

So, for me personally, the physics win over the coolness factor, and I now regard the hexagon (in the case of the concertina) as an approximation to the circle, rather than to the rectangle. After all, Sir Charles Wheatstone was a physicist!

 

Yours interdisciplinarily,

John

[Geoffrey Crabb]

Geoff Crabb has made a lovely concertina with 16 sides; as I recall it has facets but no gussets.

 

More correctly, No individual gussets, no small external leather hinges and no papers.

 

 

 

 

I'll write more when get the time.

 

Geoffrey

Edited August 28, 2014 by Geoffrey Crabb

[Terry McGee]

On the other hand, a hexagon is just a single step of development away from a rectangle.

 

Sir, I must protest!

 

A hexagon is two single steps of development away from a rectangle. (This program bought to you by the number 5.)

 

While I did come down a bit hard on the number 7 ( 360 divided by 7 is 51.428571428571428571428571428571), the number 5 is actually reasonably friendly.

 

Number of sides: Included angle:

3 120

4 90

5 72

6 60

7 51.428571428571428571428571428571 (etc)

8 45

9 40

10 36

11 32.727272727272727272727272727272 (etc)

12 30

 

Terry

Edited August 29, 2014 by Terry McGee

[Jnr Concertina]

Speaking of shapes.....ever seen a three-sided concertina? Or a picture of one?