New Tool/Method for Improving Reed Response

[BeePee]

Hello Brothers and Sisters of the Free Reed...

 

Here's a nifty new process I'm applying to my harmonica reeds. It's easy, quick, and effective at reducing air loss at the reed base and improving response. I've tried it on a couple of accordion reed blocks and it works, so should do the same on concertina reeds. It's nondestructive and reversible, so why not some if you more techie types give it a try and see what you think? I'm interested to hear!

 

https://youtu.be/eQP6tZRXbTU

 

Brendan Power

 

 

[Wolf Molkentin]

Hi Brendan, let's see what more qualified members will have to say to your suggestion; I'm not sure that "true" concertina reeds are having this air-loss issue, but can well imagine that (concertina) reeds of lesser quality might benefit from your method. Guess I will inspect some reeds and possibly give it a try.

 

In any event - thanks a lot for sharing your findings and putting it up for discussion here!

 

Best wishes - ?

 

P.S.: I have been considering the use of such sticks for reed tuning: applying some material at the top and then filing the added material (similar to adding solder, but possibly more accessible when the reeds are not just very slightly, but also not very much sharp).

[alex_holden]

Interesting idea, but it's a workaround for inaccurately fitted reeds. It shouldn't be necessary on high quality concertina reeds and would probably increase the likelihood of reeds sticking and buzzing due to reed pan movement. That said, it might be worth a try to 'soup up' a very cheap concertina particularly if it contains harmonica-style reed plates.

[BeePee]

@ Alex: By 'high quality concertina reeds', I presume you mean the reed/shoe combination? I'm interested to know what is considered to be high quality in terms of reed/slot tolerances in concertinas. Harmonica customisers would aim for 5 to 10 microns at most after embossing (0.005 - 0.01mm). If concertina reeds have greater tolerances than that, then I think they would benefit from the nail polish as long as they are secured in a well. But from what you say,that security is not a given - because the pan is wood and warps slightly according to moisture in the air, I presume. Does anyone make pans of stable non-absorbent materials, such as plastics?

 

@Wolf: A good reversible tuning solution for free reeds is Blue Tack (the stuff you use to stick pictures on the wall). I've been using it since the 1980s for harmonica reeds. Once on the reed it will stay there for years, but can be lifted off instantly. I use it to get various tunings out of one harmonica. Once you have the right amount for, say, a semitone lowering, you can take the piece of Blue Tack and put it back on the reed repeatedly to get accurate pitch alteration depending on which note you want that reed to play. Just keep it handy by the base of the reed ready to re-stick.

[Chris Ghent]

17 hours ago, Wolf Molkentin said:

I'm not sure that "true" concertina reeds are having this air-loss issue, but can well imagine that (concertina) reeds of lesser quality might benefit from your method.

 

The clearance issues are the same with concertina reeds. I have seen on a highest quality Wheatstone concertina the frame tapering in towards the reed in the last few mms to the point there seemed to be no clearance and when this was shown to me it was understood to have been done for precisely the reason the polish is applied in the video. Any gap around the reed is essentially a necessary leak. It is not a surprise only best quality reeds might have had this; apart from the technical difficulties, lesser quality reeds could be more easily improved by lifting the quality of the clearance all round.  Once this was done I can imagine someone saying, what else can we do? Do we need this clearance where the reed doesn't really move? 

 

I do wonder at clearances figures like 5 to 10 microns at the most?  BeePee, how is this being measured? On a harmonica red plate there are not be the forces which shift clearances according to the weather but even so. In a concertina reed you would be asking a reed to not deviate sideways over as much as 20-30mm. Perhaps a surface ground reed might pass this test but a hand filed one?

[alex_holden]

7 hours ago, BeePee said:

@ Alex: By 'high quality concertina reeds', I presume you mean the reed/shoe combination? I'm interested to know what is considered to be high quality in terms of reed/slot tolerances in concertinas. Harmonica customisers would aim for 5 to 10 microns at most after embossing (0.005 - 0.01mm). If concertina reeds have greater tolerances than that, then I think they would benefit from the nail polish as long as they are secured in a well. But from what you say,that security is not a given - because the pan is wood and warps slightly according to moisture in the air, I presume. Does anyone make pans of stable non-absorbent materials, such as plastics?

 

Hi Brendan, I tend to use "reed' as a shorthand for "reed assembly comprising a frame, clamp, two screws, and tongue". I don't have an accurate way to measure the clearance - I fit the reed tongues to the frames by eye, looking at the light coming through the gap under a backlit microscope. I aim to get it as tight as I can without the reed misbehaving if I apply moderate finger pressure to the frame while I sound it on the tuning bellows (simulating what happens when the reed pan expands due to humidity and squeezes the frame). The tip to frame clearance can be very small because the frame doesn't tend to distort lengthwise. The side clearances have to be a bit wider if the reed is to perform reliably. As Chris suggests, it's possible to go tighter near the clamp than near the tip, though ideally you want to always have some clearance all the way to the clamp or the reed may be prone to misbehaviour (I've seen this on vintage reeds where a microscopic bit of oxide or dust or something is interfering with the almost-zero clearance near the clamp). The clearance should be even on both sides for good pitch stability. Shorter reeds can get away with tighter clearances than long ones because long frames are more easily distorted. As a very rough rule of thumb, I'd guess good concertina reeds have approximately 1-1.5 thou side clearance (25-40 microns) on the sides near the tip, tapering down to a bit less near the clamp, and they have maybe 0.25-0.5 thou at the tip (5-10 microns).

 

There are one or two South African makers making acrylic reed pan boards for stability. There is some debate as to how this affects the tone of the instrument.

 

Incidentally in the video there's a part where you refer to the shim blade thickness as "0.01mm or 100 microns". By my calculations that would be 0.4 thou or 4 thou. Did you mean "0.1mm or 100 microns"?

 

This discussion gave me a thought. What if the clamped part of the tongue sat in a rebate that was milled a thou or two below the surface of the frame? I think it would have a similar effect to the harmonica "reed shaping" technique without the need to form a tight downward bend at the root of the tongue.

[Richard Mellish]

1 hour ago, alex_holden said:

 

Hi Brendan, I tend to use "reed' as a shorthand for "reed assembly comprising a frame, clamp, two screws, and tongue". I don't have an accurate way to measure the clearance - I fit the reed tongues to the frames by eye, looking at the light coming through the gap under a backlit microscope. I aim to get it as tight as I can without the reed misbehaving if I apply moderate finger pressure to the frame while I sound it on the tuning bellows (simulating what happens when the reed pan expands due to humidity and squeezes the frame). The tip to frame clearance can be very small because the frame doesn't tend to distort lengthwise. The side clearances have to be a bit wider if the reed is to perform reliably. As Chris suggests, it's possible to go tighter near the clamp than near the tip, though ideally you want to always have some clearance all the way to the clamp or the reed may be prone to misbehaviour (I've seen this on vintage reeds where a microscopic bit of oxide or dust or something is interfering with the almost-zero clearance near the clamp). The clearance should be even on both sides for good pitch stability. Shorter reeds can get away with tighter clearances than long ones because long frames are more easily distorted. As a very rough rule of thumb, I'd guess good concertina reeds have approximately 1-1.5 thou side clearance (25-40 microns) on the sides near the tip, tapering down to a bit less near the clamp, and they have maybe 0.25-0.5 thou at the tip (5-10 microns).

 

There are one or two South African makers making acrylic reed pan boards for stability. There is some debate as to how this affects the tone of the instrument.

 

Incidentally in the video there's a part where you refer to the shim blade thickness as "0.01mm or 100 microns". By my calculations that would be 0.4 thou or 4 thou. Did you mean "0.1mm or 100 microns"?

 

This discussion gave me a thought. What if the clamped part of the tongue sat in a rebate that was milled a thou or two below the surface of the frame? I think it would have a similar effect to the harmonica "reed shaping" technique without the need to form a tight downward bend at the root of the tongue.

On that last point, I had the same thought myself at the start of this thread, but on reflection I think what matters is only that the gap should be as small as possible without risk of fouling, not whether it is at the corner of the slot or inside the slot, because the part of a reed near the clamp hardly moves anyway. Further along, the reed moves into and out of the slot, so some of the time there are large gaps and some of the time just the tiny clearance at the sides.

 

But others know more about how a reed works than I do, even if my background was as a physicist.

[BeePee]

My mistake on the video: I said 0.01mm was 100 microns when it is actually 10.

 

I emboss over a backlit plate under a microscope. If a 0.01mm shim starts to jam but the reed still swings I know gaps are close.

 

Thanks for the info. My friend Eddy Jay has made an acrylic pan for a concertina he's working on, still to be tested I think.

 

There are similar arguments in the harmonica scene about comb materials: wood vs. metals vs. plastic... To me the airtight seal and reed/slot tolerances are the main things to get right, materials are secondary, but others are passionate about one or the other.

 

 

[David Barnert]

On 1/17/2019 at 7:43 PM, BeePee said:

@Wolf: A good reversible tuning solution for free reeds is Blue Tack (the stuff you use to stick pictures on the wall).

 

Amazing. Within 25 hours of each other, two mentions of using Blu Tack for very different applications in concertina maintenance. Brendan uses it for tuning reeds and Simon uses it as a quick-qnd-dirty fix for pads that come unglued.