Alternative für Windladen

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Piet Paardekam
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Alternative für Windladen

Beitrag von Piet Paardekam » So 12. Feb 2017, 11:19

I made a quick sketch of a membrane solution for pneumatic trackers such as in the Beijertje or the Höffle as a replacement for the complex windchests in the original design.
The solution consists of a block with holes, a wind inlet cap, and a membrane with membrane cap. See drawing. Making is quite easy and nothing can go wrong.
Drill the holes in the block. You can make as many positions in the block as you want. Make them as small and light as possible. You can even make one block per pipe, or a two-sided block for 20 pipes etc. For the way you place the pipe in the block there are a lot of alternatives. You may have the membrane lying or standing up, but not upside down. If you make a block for more than one pipe, you make only one wind inlet cap that feeds all the positions of course. Every membrane has its own membrane cap.
The depth of the membrane cap must be at least 4mm to have enough space for the lifting membrane. For the membrane ONLY use the first quality membrane leather of no more then 0,35mm thick (softly pressed when measuring). In the membrane is a hole for the lost air. Take a steel nail with a thickness of 1,5mm and grind off the point flat. With this nail you punch a hole in the membrane on the place where the inlet hole is in the block. Use a piece of hardwood under the leather while punching to get a sharp hole. The hole will shrink a bit after punching and will have the perfect diameter.
You can make the cap in different ways. But keep the dimensions of my drawing. I did test several dimensions and these did seem to be the best. On the photos you see a quick-and-dirty solution for my prototype and even that works excellent. Make the membrane as large as the cap. Use only two small screws for the cap. You also can cut two triangles from the membrane on the place of the screws in stead of making holes. Of course make some spare membranes.
Place the leather on the block and whipe it flat. Then press gently your thumb on the leather on the place of the holes, so that you just can see that a hole is below. No more. Close the cap and try. Normally it works directly. If not, take off the cap, stretch the leather, little press (or not if the leather is very flexible) and close again. You will be supprised how good I works in the first try.
So no regulation screws. To much works and absolutely unnecessary. In the unlikely case that a membrane does not work: open the cap, stretch or replace the leather and go. The hole of 1,5mm is optimal in practice. The dimensions of the hole in the block are 12mm. With this dimension you can feed a double row of melody pipes easily and single pipes until basses of 80 cm in length. I did test this widely with several pipes.

The big advantage (besides the simple construction) is that you can make as many blocks as you need and if something is wrong you only have to open that specific cap.

By the way: the holes in my trackers are 2,4mm. This is large enough for good pneumatic working and prevents leaking when the roll is not punched exactly “in track” .
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Zuletzt geändert von Piet Paardekam am So 12. Feb 2017, 12:37, insgesamt 2-mal geändert.

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Reinhard
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Re: Alternative für Windladen

Beitrag von Reinhard » So 12. Feb 2017, 12:26

Davon abgesehen,dass die umfangreiche Beschreibung sehr gut ist,möchte ich noch eine Ergänzung hinzufügen.
Wie beschrieben,zieht sich das Ventilleder (0,4-0,5mm) nach dem Lochen mit einem plangeschliffenen Nagel immer etwas zurück. Das bedeutet,dass der Nagel größer sein muss als das gewünschte Loch.Es ist also unerlässlich an einem Reststück einige Proben mit verschiedene Durchmesser vorzunehmen.
Ich habe mit einem 1,8mm Nagel eine Lochgröße von 1,4mm bekommen. Allerdings darf das Leder dann nur flach hingelegt nicht gespannt sein.
Daher könnte es sein, um das in der Skizze bezeichnete Loch von 1,5mm zu erhalten,hier einen Nagel von 1,9-2mm zu verwenden.

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Piet Paardekam
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Re: Alternative für Windladen

Beitrag von Piet Paardekam » So 12. Feb 2017, 20:34

I did test several hole diameters. When I punch with a nail of 1,5mm I had the best results. That is what I mean with 1,5mm in the drawing . As I said in the text, the hole will shrink somewhat. Punching with 1,2 was to small. Punching somewhat larger did not improve the working. A rule of thumb is that a membrame hole of half the diameter of the hole in the tracker is the optimum value. My tracker holes are 2,4mm. Holes of 3mm should work best with 1,5 actual diameter, so punch somewhat larger.
The thinner the membrane leather is, the faster it will react.
The best thing is to make a protype like me and start experimenting with different sorts of leather and diameters in the membrane. You will get feeling for it and find the best combination. Use a real flute and the wind from the bellows you will use the membrane for. Experimenting in practice is always better than theory with organ building.

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