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Author Topic: Tuning reed plates (rather than individual reeds)  (Read 4118 times)

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Theo

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Re: Tuning reed plates (rather than individual reeds)
« Reply #20 on: October 13, 2016, 10:58:55 AM »

. . . . .    And I just want to see how they do it with the reeds in the box.   . . . .   ;)

I can't visualise how you could show that on a video.  The tools are tiny, the workspace is restricted, in part the work is done by feel, and as diatonix says  so much if what goes on is down to experience of how little force to use, how to prepare tools and so on.

I'll attempt a brief explanation, and I assume you know something of how reeds are tuned outside the box.   This is my method, and there are many variations.  First step is to sound the reed in the box.   I use the instruments own bellows, because I work on many different sizes of box and this works for me.  I have a plate projecting from the edge of a bench that fits into the bellows folds and holds the open end of the bellows facing upwards.  The lower end of the bellows hangs down and has the other end of the instrument attached.  The reeds have to be stopped off so that only one reed plays at a time.  Masking tape under the reed block is the main way of doing this if the box does not have built in registers.  Place the instrument on the bellows, sound one note, check pitch on Peterson tuner, lift off, tune reed tongue up or down as appropriate, replace and test the same reed again and repeat till you reach the target pitch. And so on.  The tools I use are the same as for tuning on the block outside the instrument: scratcher, file, reed lifters, support plate.
« Last Edit: October 13, 2016, 11:01:02 AM by Theo »
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Theo Gibb - Gateshead UK

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Stockaryd

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Re: Tuning reed plates (rather than individual reeds)
« Reply #21 on: October 13, 2016, 08:33:49 PM »

Thanks for your patience.
I have to think for a long time. And slowly!   

I think the one that best illustrates what I wondered about is the image  "final tuning" by bellingersbuttonboxes.com 

Impressed by the tuner in plexi although I do not fully understand how to switch from blowing to suction, . . .  but that is another question.

Thank you all!

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diatonix

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Re: Tuning reed plates (rather than individual reeds)
« Reply #22 on: October 14, 2016, 09:45:17 AM »

The video made by Hickory-wind is quite interesting. But I still think that a manually operated tuning bellows (the instrument to be tuned makes, as suggested by Theo, an excellent tuning bellows!) is a vital part of the process, allowing you to tune the reeds A) much faster B) more accurately since the reeds are in their natural habitat and C) under the many different conditions the box is actually used by the player, from pp to ff.
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hickory-wind

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Re: Tuning reed plates (rather than individual reeds)
« Reply #23 on: October 16, 2016, 11:43:26 PM »

The video made by Hickory-wind is quite interesting. But I still think that a manually operated tuning bellows (the instrument to be tuned makes, as suggested by Theo, an excellent tuning bellows!) is a vital part of the process, allowing you to tune the reeds A) much faster B) more accurately since the reeds are in their natural habitat and C) under the many different conditions the box is actually used by the player, from pp to ff.

To elucidate for diatonix, I have developed an air tuning table that is highly repeatable, accurate and considerably faster than bellows tuning. I started by modifying an old Hohner two row 'parts' box by adding a tube to monitor the internal pressure and vacuum (pic 1). I procured several very low pressure gauges that measure both positive and negative pressure (pics 2 & 3). To give you an idea of how sensitive they are, the first one reads full scale at 2 inches of water column. That is the same as taking a drinking straw and sucking up two inches of water-very sensitive. The second meter reads +/- 5 inches of water column that I use for small bellows area instruments like concertinas. Pressure is equal to force divided by area (P=F/A) so the smaller the area the higher the pressure for a given human squeeze force. I then played the instrument quietly, normally and stridently to see how the pressure varied. Next I developed (many trial and error steps and different blowers tested) an external blower system that can provide the exact same pressures and vacuums measured in the instrument. The blower is in an adjacent room in a soundproof enclosure so all that is delivered to my tuning table is quiet constant air pressure and vacuum. (continued next post)
« Last Edit: October 16, 2016, 11:58:04 PM by hickory-wind »
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hickory-wind

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Re: Tuning reed plates (rather than individual reeds)
« Reply #24 on: October 16, 2016, 11:56:35 PM »

These pictures shows the table with the blower on in both pressure and vacuum settings. In the upper right is a laboratory DC power supply with a 10-turn potentiometer for voltage. With this arrangement I can vary the pressure/vacuum very precisely and repeatably simulating anything between pp to ff.

With standard bellows tuning one reed (either push or pull) is being tuned at a time so 50% of the bellows motion is unproductive. Depending on how many listen/scratch-file/listen cycles are needed this can amount to 10 to 30 seconds per reed of wasted time. Not a lot but for a standard 124 reed Pokerwork that adds up to 20 minutes to an hour.

The air table is completely hands/knees/feet free and provides consistent source of air. I can very precisely determine the exact pressure/vacuum where the reed starts to speak by slowing increasing the voltage to the blower while monitoring the inches-of-water-column gauge. This is vital for proper tuning so that all reeds start to sound at the same time.

Having started out with a bellows tuner and now compared the two methods I would have abandoned this air table concept had either the tuning duration or accuracy been inferior to the bellows method. I found quite the opposite to be true. Regardless of the tuning method the final result that counts is how the instrument sounds and plays after it is back together and in the hands of its owner. The reader can come to their own conclusion by listening to a demonstration of all the notes on a Pressed Wood Hohner tuned last week. The button demonstrations start at 2:10. I only wish my playing skill can catch up to my tuning skill:)

https://youtu.be/Ziitd8SBvJM

To bring this discussion back to the original thread, the air table in conjunction with the longplate fixtures shown in pictures several messages before this provide a very easy method of troubleshooting and coarse tuning both the inner and outer reeds on longplates. The final tuning occurs after the reedplates are remounted onto the instrument. The last picture shows some of the many fixtures (hanging from the ceiling) that support and seal the instrument end being tuned while on the table using the instrument buttons.

I have nothing against bellows tuning tables and completely agree they can work beautifully and accurately. I did feel the need to respond to the suggestion that an air table is either slower or less accurate than a bellows setup. I invite any tuner or box enthusiast to visit my shop and try the table first hand if you are ever visiting western New York, USA.

Scott

BellingersButtonBoxes.com
« Last Edit: October 17, 2016, 12:02:24 AM by hickory-wind »
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Peter Courtney

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Re: Tuning reed plates (rather than individual reeds)
« Reply #25 on: November 27, 2016, 09:21:53 AM »

I Have tuned a lot of these. I take the reed plate out so I can tune the reeds facing rather than pushing through especially if they are brass.
I remove the keyboard and make an adaptor with a hole in it, leather glued to both sides to fill the void between the box and the a tuning table so you can pass the air through.I find if i want concert then depending on the box have tune about 12 to 15 cents flat. This allows for the leakage as the plates are no longer waxed in. Just hold them down as firmly as you can Takes some practice and patience but I have done done boxes well over a hundred years old this way with good results. I us a Petersen digital strobe tuner
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RPr

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Re: Tuning reed plates (rather than individual reeds)
« Reply #26 on: November 28, 2016, 12:52:43 AM »

I have a similar situation. Mine is a Czechoslovakian box with a reed plate. The plate is not glued in, it is held with a few inverted L shaped staples then waxed in place.

I need to get to the reed leathers on the underside, so I intend to pull the staples and lift the reed plate out of the wax. The box is tuned to G# plus 50 cents so I have no idea what pitch A was used.

To tune the reeds in place would require removing the button board and clappers and finding a way to direct air into each reed hole for the pull note and isolating each reed on the other side for the push note.

It is the kind of project you do because you simply want to do it, there is no way to cost justify it nor should you have to. Sometimes it is just fun to get the creative juices flowing and here is a project already at hand.         
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