Instrument Repair Inquiry

[cebrul]

I was just reading this post by Nancy Shinn online (https://www.jennifercluff.com/check.htm) about the adjustments for the back connectors of flutes. I noticed that when I pressed my F-key, the B flat key was maybe half a mm from sealing, which caused a leak if I do the third octave B flat (using the B natural key, whileas if I use the B flat key, it seals perfectly). My temporary solution was to put use a little piece of paper (a sticky note, but that doesn't really must of an adhesive on it on the metal side of the F/B flat back connector, so that the little piece of paper was enough to seal the B flat key when I press on the F key).

I sent it over to a band repair tech, and they completed the repair surprisingly fast. However their fix was to bend the F/B flat back connector just enough to seal the B flat key when the F key was pressed: https://imgur.com/a/qHaB3rj.

This results to the F/B flat connector to not fully lay flat on the F key connector as seen in the image attached. Is this a normal fix? I read on the article above that they use pieces of shims to adjust this height if there were no adjustment screws on the back connectors... I also noticed the tiniest scuffs on the F/B flat connector key that I assume was from them bending the key - and I just needed to know if that was something that was normally done by techs, since I would prefer something I spent 5 grand on to not be mishandled...

Anyways, do let me know your thoughts. I'm sure if the felt on the F/B flat back connectors doesn't compress anymore, I'd just wait a couple of years until I send my flute in to a professional flute tech for the connector to be bent (ever so slightly) back to the way it used to be. Again, I might just be OCD, but I'm unfamiliar if this is a conventional way of fixing this, or if I just had a bad tech.

[JButky]

You've got lots of factors here for that back connector. To answer your question indirectly, let me tell you how the mechanical design for this function should be setup.

The plates for each section in proper adjustment should be "FULL CONTACT" not tipped, twisted, etc. The full face of one part must meet the full face of the other..

Cushion, Never any more thickness for the rigidity of the material used to keep it quiet. Less is more if for no other reason than compression will occur requiring further regulation. It's a balance between material choice and how much you need to make up for proper regulation, LOTS of choices here..

Bending? Is it acceptable? YES, if it is done to achieve the goals above. When plates don't meet completely, they will bend out of regulation since force is applied to a singular point rather than spread out over the face of the plate. The greater the surface area in contact, the greater the force is spread over the surface. When concentrated on a point, further bending out of regulation will happen faster.

The Answer is not simple. There are many factors to consider and different repair people do what works without considering all of these things. The Bb side of things is tipped on your flute, and that felt will still compress. Will it work? sure, it's not outrageous, but can it be better? absolutely!

When the plates are parallel with a minimum of material just to keep it quiet, then you will have the longest lasting adjustment. That's the ideal techs should try to obtain. Sometimes that requires a lot more effort than not given how any particular flute was made. They all have their individual quirks...

[cebrul]

Thanks for the reply Joe! I mean, for the meanwhile, it seems like it works fine, but I am curious what you mean by "bend out of regulation"? You mean eventually it'll flatten out and it will be back to the way it used to be?

I mean I guess the best thing would have to be to have a little bit of a thicker felt, which would need to have to take everything apart. So I assume bending the plate slightly would be the quick fix. But for what it is right now, there's no point changing it yet, maybe not until the next COA when maybe it can be bent back parallel to the plate below, and maybe requiring a little bit of a thicker felt or something, right?

You've got lots of factors here for that back connector. To answer your question indirectly, let me tell you how the mechanical design for this function should be setup.

The plates for each section in proper adjustment should be "FULL CONTACT" not tipped, twisted, etc. The full face of one part must meet the full face of the other..

Cushion, Never any more thickness for the rigidity of the material used to keep it quiet. Less is more if for no other reason than compression will occur requiring further regulation. It's a balance between material choice and how much you need to make up for proper regulation, LOTS of choices here..

Bending? Is it acceptable? YES, if it is done to achieve the goals above. When plates don't meet completely, they will bend out of regulation since force is applied to a singular point rather than spread out over the face of the plate. The greater the surface area in contact, the greater the force is spread over the surface. When concentrated on a point, further bending out of regulation will happen faster.

The Answer is not simple. There are many factors to consider and different repair people do what works without considering all of these things. The Bb side of things is tipped on your flute, and that felt will still compress. Will it work? sure, it's not outrageous, but can it be better? absolutely!

When the plates are parallel with a minimum of material just to keep it quiet, then you will have the longest lasting adjustment. That's the ideal techs should try to obtain. Sometimes that requires a lot more effort than not given how any particular flute was made. They all have their individual quirks...

[JButky]

Thanks for the reply Joe! I mean, for the meanwhile, it seems like it works fine, but I am curious what you mean by "bend out of regulation"? You mean eventually it'll flatten out and it will be back to the way it used to be?

Yes, when the contact area is concentrated on one end and the rest of the plate is unsupported, pushing on it via the back connector will tend to flex it back since ALL of the pressure is concentrated on that one side. It is also far away from where it will bend, so leverage is working against you and in favor of bending it back to parallel where the pressure is spread across the plates

There are many ways to deal with it for a longer lasting repair. Adding non compressible material with a thin layer of cushion is one way, Adjusting one or both plates to have a small parallel gap is another. It depends on the flute and how it was constructed as to a method for making it more stable.

Of course there's the time and money aspect for the repair that also needs to owner to decide. I can do this, good, quick, inexpensive.... or I can do this... better, longer lasting, but more expensive and a bit more time...

Keywork design and quality of materials will also determine whether it will fail sooner or later.
Regulation is always an issue because of torque, pressure, compression and materials that need to function a certain way until they eventually fail. You can do 5 quick, cheap repairs or one during the same time frame depending on a whole lot of factors...But this is the nature of the beast..