Norman Concertina Construction

[Howard Mitchell]

I had to take the end off my Andrew Norman Anglo to re-fit a bush. As it was the first time I'd taken it apart I took some photographs and put them on http://www.hgmitchell.plus.com/hgm/norman.htm

 

Howard Mitchell

[john]

Thanks for posting the photos Howard. I found them quite interesting. I wish I were able to see more different makes of concertina this way.

John

[Richard Morse]

There are some photos our Morse concertina innards here

[Ivan Viehoff]

Both the Norman and the Morse have what look like pieces of wire stuck onto the longer valve flaps (with the red disk), which is not something I have in my Lachenal, nor have I seen in pictures of the innards of other vintage concertinas.

 

On the other hand, the vintage concertinas have these thin pieces of wire sticking out of the side of the reed chambers, whose purpose appears to be to stop the valves in the chambers from lifting too much, though there is no restraint on the valves on the bellows side.

 

Why all these differences?

[d.elliott]

Ivan,

 

the wire sticking out of the chamber walls (valve pin(s)) is to restrain the tip of the valve from either catching on the chamber wall, or its gasket, and sticking open. Or perhaps even being drawn into the pad hole.

 

The wire on the accordian reed valve is to control the degree of movement (hence response) of those valves that need it, due to their size/ length by altering the stiffness of the valve and ensuring it shuts off.

 

On the classic concertina valve/ reed design, the valve pin in the chamber side of the pan performs this function more or less. However on big reeds, particulalry on double acting baritones or anglo baritones the very large leather valves on the non chamber side of the pan often had valve springs fitted see attached picture.

 

Dave

[Richard Morse]

The difference in valving is due to the difference between the qualities of accordion/concertina reed valves and the way their installed.

 

Accordion valves are typically cow leather, specially tanned, skived (thickness sliced) and cut along the grain for good flexibility, memory (springiness to return), and seal (to seat well to limit air leakage).

 

Accordion valves do all this quite well though due primarily to cost-savings concerns, they are rectangular (for minimal wastage fabrication) and made from cow hide (cheaper).

 

That strip of wire you see on the longer/larger accordion valves is a thin bit of spring steel (not round, but flat) "helper spring" than encourages those valves to seat (return to be flat against the vent hole) - a memory aid.

 

Concertina valves are typically made of hair sheep leather, specially tanned, skived, and punched out of certain parts of the hide along the grain for excellent flexibility, memory and seal.

 

Why does this make them better than accordion valves? To begin with, concertina valves are not rectangular but trapezoidal with radius ends. This lets the valve bend more easily from the tip to the butt which means that there's incrementally increasing memory capacity toward the butt, right were you need that return "strength" the most (as it has to deal with all the valve "weight" from there back to the tip).

 

Hair sheep is also less dense and has a spongier structure that cow. This allows hair sheep valves to be skived thicker which increases memory. Hair sheep "tooth" is also finer and softer textured than cow which makes for a better seal. And for some other reasons (I don't know why) hair sheep vavles seem to last a lot longer than cow valves (due to the type of leather? environment it's in? chemicals it was treated with?).

 

While both type of valves work well when brand new, you can really discern the performance difference when they age. Most of the bending of accordion valves winds up focusing near the butt eventually weakening the valve there so that it not so much flexes along the length uniformly (like it did when it was new), but now more like a hinged door where it flexes near the butt and the rest hardly flexes at all. All that weight stiffly flopping around on a more flexible hinged area. The helper spring is *really* essential here for the longer/heavier valves.

 

Concertina valves bend more near the tip and incrementally less as you get toward the butt, and due to the uneven flexure do not unduly stress the material near the butt to degrade as quickly as accordion valves do. There is always more strength near the butt and less mass near the tip of concertina valves.

 

There are also those bits of stiff wire found in concertinas which are valve limiters as Dave has explained, very different from spring helpers.

[Frank Edgley]

"Why does this make them better than accordion valves? To begin with, concertina valves are not rectangular but trapezoidal with radius ends. This lets the valve bend more easily from the tip to the butt which means that there's incrementally increasing memory capacity toward the butt, right were you need that return "strength" the most (as it has to deal with all the valve "weight" from there back to the tip)."

 

Except, maybe, for the original Jeffries valves which appeared, at least to me, to be rectangular, with square corners. I believe they were cut out by hand with scissors or similar tool.

[Richard Morse]

Except, maybe, for the original Jeffries valves which appeared, at least to me, to be rectangular, with square corners. I believe they were cut out by hand with scissors or similar tool.

Seems like they didn't have the punches at that point. If they had I'm sure they would have used them.

[Peter Brook]

Being new to concertina ownership I'm uncertain of whether the bellows should need leather food or anything?

 

Does anyone else put anything on their leather bellows?

 

I have a Norman Anglo which was made in February 1997, so it is 7 years old.

 

advice greatly appreciated.

 

thanks,

 

Peter

[JimLucas]

Does anyone else put anything on their leather bellows?

I have never applied any substance to "condition" the bellows of any of my several concertinas, and none of them has shown any deterioration in the time I've had them. In fact, some are over 100 years old (though I'm not) with no sign of any "treatment", and still supple.

 

I have a Norman Anglo which was made in February 1997, so it is 7 years old.

I expect that after 5 times that long, your bellows will be in just as good shape without "treatment" as with, and quite possibly better.