Finger pressure guage

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HMannfan
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Joined: Fri Nov 01, 2013 10:55 am

Finger pressure guage

Post by HMannfan » Wed Nov 29, 2017 2:53 pm

Is there a device to measure the amount of force required to close a key? Should the pressure required be the same for all the keys? I've read it should only take about 1 1/2 oz. of pressure to seal a pad against the chimney. Some of the springs are a heavier gauge which would lead me to believe there are differences, specifically keys that are normally closed.

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JButky
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Re: Finger pressure guage

Post by JButky » Wed Nov 29, 2017 6:07 pm

Yes, there are leaf spring gauges that measure this as well as air pressure gauges to actually measure the sealing of the pad to the tone hole.

The leaf spring gauges as far as I know are mostly homemade while the air pressure test machines are readily available in the industry..
Joe B

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JButky
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Re: Finger pressure guage

Post by JButky » Wed Nov 29, 2017 6:12 pm

HMannfan wrote:
Wed Nov 29, 2017 2:53 pm
Should the pressure required be the same for all the keys?
This is very subjective. You cannot have the same finger pressure simply because various key combinations activated by one finger are sometimes one sprung key and other times 3 keys in some cases. There is a blending and rule of thumb for adjusting spring tensions to hide the differences from tactile feel for these scenarios. So to be technical, yes, the same pressure can be applied to all keys to make them seal and yes you can still make an instrument feel even by compensating for different finger strengths and combinations..
Joe B

HMannfan
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Re: Finger pressure guage

Post by HMannfan » Thu Nov 30, 2017 12:03 am

Thanks, Joe.
The reason I started thinking about this is I have a professional flute player test play all my repaired instruments prior to giving them back to a student. I have large, very strong hands and fingers (I was a carpenter for 40yrs) and she plays with a much lighter touch. Occasionally she will remark on how quickly a particular flute will respond mechanically. I surmise this may be related to the action of the springs, given the related mechanical parts are in good shape. Might this indicate that some springs may be getting weak? How can I tell if a spring should be replaced? A lot of these instruments are 15 to 20 years old.

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JButky
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Re: Finger pressure guage

Post by JButky » Thu Nov 30, 2017 1:15 pm

HMannfan wrote:
Thu Nov 30, 2017 12:03 am
Occasionally she will remark on how quickly a particular flute will respond mechanically. I surmise this may be related to the action of the springs, given the related mechanical parts are in good shape. Might this indicate that some springs may be getting weak? How can I tell if a spring should be replaced? A lot of these instruments are 15 to 20 years old.
Springs only need to be replaced when they are broken. Spring tension is something that can be adjusted rather easily but pulling more of a curve in the spring. That will increase the tension. It is very subjective as to what a particular player likes. But if the spring is not broken, then you should be able to adjust it pretty easily. Phosphor bronze springs on some student instruments tend to be harder to increase tension sometimes. But most stainless steel springs are easily adjustable in either direction. (heavier or lighter feel)..
Joe B

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