Reed dimensions

[david fabre]

Hi all

 

Could somebody here give me typical dimensions for reeds (concertina, or accordeon, or both)

In particular : the thickness of the reed and that of the plate/shoe, and the size of the "clearance" (is that the right term ?) between reed and plate, at the tip and the sides.

 

I'm presently designing research projects on fluid mechanics in free reed instruments and may at some point perform some numerical simulations of the air flow through a reed. I'll tell you where we get...

 

David

Edited December 17, 2012 by david fabre

[Chris Ghent]

Hi all

 

Could somebody here give me typical dimensions for reeds (concertina, or accordeon, or both)

In particular : the thickness of the reed and that of the plate/shoe, and the size of the "clearance" (is that the right term ?) between reed and plate, at the tip and the sides.

 

I'm presently designing research projects on fluid mechanics in free reed instruments and may at some point perform some numerical simulations of the air flow through a reed. I'll tell you where we get...

 

David

David,

 

every pitch is different, and every manufacturer makes their reeds with slightly different dimensions. However as a token answer to your question, here is one pitch, with two examples, taken from a 1917 Wheatstone Model 22 English. It was copied from an xls file which the forum would not let me load as an attachment.

 

note A440

reed length 24.5mm

root width 2.85mm

tip width 2.5

Frame thickness 2mm (Jeffries are closer to 2.3mm)

Clearance between frame and reed at best 1 thou (.025), bad Lachenal around 4 thou (.1)

 

What follows is the profile of a simple reed. I call it this because it is not a much of a taper (which the reeds higher than it are) and it is not a valley which the reeds below it are. The rows of numbers are:

1-23 is the distance from the root in mm. 1mm has no reading because I could not measure that close to the clamp.

 

The numbers under the 1-23 are the thickness of the reed at that point for two examples of A 440, expressed in thou (.025). I use thou here because I find .025s are unwieldy. Plus I was brought up on thou.

 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

 

14.8 13.8 12.5 11.3 10.9 10.2 10.0 10.0 9.7 9.3 9.2 9.0 8.9 9.0 8.8 8.5 8.5 8.4 8.4 8.4 8.4 8.3

 

14.2 13.2 11.9 10.7 10.3 9.6 9.4 9.4 9.1 8.7 8.6 8.4 8.3 8.4 8.2 7.9 7.9 7.8 7.8 7.8 7.8 7.7

 

 

 

Hope this helps...

 

Chris

[Chris Ghent]

David,

 

Just logged back in and realised the formatting of the above has been lost a little.

 

I'll work out a way to display it more clearly...

 

Chris

[jenovak]

Chris,

 

So what you are saying is that the reeds taper in thickness from .0148 or .0142 near the clamp to .0083 or .0077 at the tip for these two A440 reeds. Values are in inches.

 

I'm surprised that the root to tip width is tapered, I thought that they were all straight.

[Chris Ghent]

Here is a better setout. The top numbers are mm, the bottom ones are .001".

[Chris Ghent]

Chris,

 

So what you are saying is that the reeds taper in thickness from .0148 or .0142 near the clamp to .0083 or .0077 at the tip for these two A440 reeds. Values are in inches.

 

I'm surprised that the root to tip width is tapered, I thought that they were all straight.

I am not sure where you have missed my meaning, the taper you refer to in my quote is thickness. I suspect you are referring to width, and many modern makers are using parallel widths because reeds then can be ground to width in bulk on a surface grinder which is a very accurate method. Or they are using wire EDM which is similarly accurate. In the old days the width taper (in this case 2.85mm to 2.5mm) was an aid to getting a tight fit. It would always fit, if you made it too narrow you could always cut the end off and put it further in. With a parallel reed if it is too narrow it qualifies for the final trajectory, over your shoulder towards the scrap bin, or into it if you have had plenty of practice.

[david fabre]

Thanks Chris , this is extremely helpful !

 

So, the average thickness is about 8 thou, which is about 0.2 mm.

(btw it's the first time i hear about this strange unity. French translation seems to be "mil")

 

I'm also surprised by the strong variation of thickness. Is it only a result of filing, or are the steel plates of which the reeds are made already tappered ?

 

About the slight tapper in width, i had not noticed that. I'll have a closer look at my wheatstone. It's curious that this taper was lost on concertina reed while it is still present (and much more pronounced) for accordeon reeds. Any thoughts ?

[inventor]

You need to get in touch with "Ukebert" on melodeon.net . He is an engineer and musician who has done similar research on free reeds, and may be able to help.

Inventor.

[Chris Ghent]

 

So, the average thickness is about 8 thou, which is about 0.2 mm.

(btw it's the first time i hear about this strange unity. French translation seems to be "mil")

 

I'm also surprised by the strong variation of thickness. Is it only a result of filing, or are the steel plates of which the reeds are made already tappered ?

 

About the slight tapper in width, i had not noticed that. I'll have a closer look at my wheatstone. It's curious that this taper was lost on concertina reed while it is still present (and much more pronounced) for accordeon reeds. Any thoughts ?

The reed profile taper is from filing.

 

I wouldn't read too much into the historical path, as in parallel versus tapered reeds.

 

There is a relationship between the amount of taper in the frame under the reed and the taper in the width of the reed. Accordions do not have much relief taper in the frame under the reed, but a lot of taper in the width, which may perform the same function (you have to think how the gap between the reed and frame increases as the reed goes down through the slot). I think modern makers who use parallel reeds do so for manufacturing reasons, though there might be a technical performance advantage I have not understood.