Key leaf spring repair

[Viking of Kiev]

Hi guys!
A while ago I found spring of my flute's F-nat key broken. It no longer presses well to its seat and doesn't seal. The flute is a Francois Baubet 4 keyed flute in mopane. It is 10 years old and it would need a bit of a repair but now I hardly can afford sending it to Francois from where I live and in all I'd prefer giving it to someone who goes to Ireland in person than to ship it by PS.
And I doubt I have any repairer here who can reliably fix my issue.
So, do you know any (temporary) amateur way to repair a broken leaf spring of a key?

The spring broke by the pin (or rivet) to which it is attached on the back side of the key touch. I lost the spring itself. I even found a substitute pieces of steel plate and cut it into right shape but revealed I can't attach it to the key as this backside pin appeared to be too short to be riveted to hold the spring properly.
You may see it all on the pictures. I often see keys on someone's flutes wrapped with rubber band. It seems same issue occurs from time to time. But the band works well only for those keys that placed longwise, the Fnat key being at right angle to the flute axis so rubber band here's next to no help.

Any ideas guys?

Here are links to pictures. Can't figure out how to insert them here, BBCode doesn't work for me.
There's the broken Fnat key on the first two.
Healthy Eb key just to imagine what that type of keys and springs look like when unbroken.
Current fix.

https://ibb.co/whRBnDf

https://ibb.co/vJdRvdr

https://ibb.co/2YzZnLM

https://ibb.co/gvyxQpn

[Loren]

Best options:

1. Write to Francois and explain the situation. He should be happy to have you ship him just the key which he can re-spring and send back to you.

2. Is there anyone near you who does woodwind repair work? Or a jeweler? If so, you could ask Francois to send you some already punched and formed springs (get a whole set - the proper spring for each key - so you are prepared the next time this happens), and take the key and the spring to the local woodwind repair person or jeweler. Either one should have no problem properly installing the spring on the key.

3. Get the spring from Francois and install it on the key yourself. He should be able to talk you through the relatively simple process.

[chas]

Temporary repair: put a rubber band around the flute body between the key pivot and the hole it goes to. Experiment with different rubber bands and how many times to wrap them around. I used that for a couple of years on an antique no-name flute and it worked great.

I hope you're able to stay safe.

[Julia Delaney]

The rubber band idea, above, is perfect. It is cheap and effective.

You will look like a totally authentic Irish flute player, and have genuine street cred!

[Nanohedron]

The rubber band idea, above, is perfect. It is cheap and effective.

You will look like a totally authentic Irish flute player, and have genuine street cred!

Totally.

[Terry McGee]

I'm not sure that a single rubber band is enough to deliver street cred. But toss in some electrician's insulation tape wrapped around the barrel, and a Cheney hose clip or two and you're there. Rather like jazz sax players - they would never want to be seen on stage with a shiny new sax.

Now, I don't think we should underestimate the task of respringing a Short F key and getting it working "just so". You want it to be light but snappy in operation, not heavy or sluggish. Achieving that is a delicate blend of spring thickness and width, and spring length and curvature are particularly critical. But Viking of Kiev, I think you should contact M. Baubet to see what he would recommend. If that isn't going to work for you, take the instrument to meet your local woodwind repairer and see what they can offer.

[Julia Delaney]

Nah. Just get a rubber band. Then adjust the resistance. It's trickier on the short F but it can be done.
And in any case, it's good to become comfortable with using the long F.

If it's good enough for Cathal McConnell it's good enough for you and me.

https://www.youtube.com/watch?v=lm3QDcE57_Y

[Viking of Kiev]

He should be happy to have you ship him just the key which he can re-spring and send back to you.

Strangely but this simple idea didn't come to my mind:). Possibly because I've been hoping to send Francois the whole flute for more thorough repair - there's a crack in the head going through the embouchure hole. It appeared when I had quit playing for about two years and was not paying attention to my flute at all. It was her revenge on me, evidently. But yet it still works - the head is lined and there's no leak despite the crack.

Is there anyone near you who does woodwind repair work? Or a jeweler?

Thought about that but who of modern woodwind repairers could fix a leaf spring of a key of an irish flute? Modern Boehm flutes mostly have needle springs - that's a different story. A clarinet and oboe repairers? Do they work with this kind of keys and springs? (I have no idea what kind of springs modern oboes, clarinets and bassoons have). So I have doubts.

Now, I don't think we should underestimate the task of respringing a Short F key and getting it working "just so". You want it to be light but snappy in operation, not heavy or sluggish. Achieving that is a delicate blend of spring thickness and width, and spring length and curvature are particularly critical. But Viking of Kiev, I think you should contact M. Baubet to see what he would recommend. If that isn't going to work for you, take the instrument to meet your local woodwind repairer and see what they can offer.

It is quite evident - all of my four keys with leaf springs work differently for me - the Eb it a bit too tight for my pinkie, the G# is the same as well, being placed uncomfortably for me (my finger falls onto its block, not on its touch, that's why I often miss it while playing), the Bb is a bit too loose and clicking on being pressed. That's due to different work of their springs I suppose.
I hope still I will have my flute taken to Francois to fix all issues, springs tension included, as soon as the stars align.


Thank you all guys for your help - I got some new ideas for fixing the problem.

But I ended up this way - I took a piece of a coil spring from a retractable ballpoint pen - there are steel coil springs about 3mm in diameter and 25mm in length. I cut a 5mm piece, bent its loose end so it could fit into a tiny hole in the flute body under the key touch I pierced with an awl and inserted this piece of spring under the key touch. It works well. A bit too tight but seals well. Haven't yet played extensively but it works. I even feel there's some space for fine adjustment. Though, let's see for how long it can stay in this form.
The result on the picture below (under the link).

(As far as I remember, I played a 8 keys Hamilton about 10 years ago, pin mounted, with this kind of springs. Their action seemed strange to me but I understand it's a matter of getting used to).

[Terry McGee]

Sounds like it would be good to get the flute back to M. Baubet for a general tidy up, Viking.

The crack through the head is probably not your fault, other than perhaps to fail to keep it in reasonably balanced humidity. I imagine in your part of the world, indoor humidity particularly in winter is very low. This leads to cracking of metal-lined sections through the weakest point - which is often the embouchure hole. Keep in mind that this can affect the barrel section too, and a crack there is often more problematic. So if there is anything you can do to keep the humidity reasonably centred, it will reward you!

Well done on the ball-point-pen spring repair! You are right to observe that coil spring action is not the optimum in our application. The coil spring resists more strongly the more it is compressed. So pushing the key halfway open is easier than pushing it the second halfway. The simple long, flat leaf springs you see on clarinets are similar. They just rely on bending the spring. But the curved leaf springs used on early and 19th century flutes, and that we continue to use, are much sneakier. As you push down the key touch, the tip of the spring (the only bit that should contact the flute) slides forward towards the fulcrum (the pin), reducing the spring's leverage, and countering the spring's natural tendency to feel stiffer. So the key can feel snappy, rather than increasingly resistant. It's a beautiful thing when you get it right! Equally, it's not an easy thing to get right!

Because sliding of the spring tip is involved in the spring action, it's good to lubricate that point on each key from time to time. And ideally clean out any gunge that might have collected there. Cork grease, or any other similar grease lubricant should be fine. Flute spring tips do need a metal plate or something similar to slide on - some old flutes didn't have that, and the tip of the spring digs a hole in the wood until it gets itself stuck, and then the key really becomes sluggish! Keep that plate clean but lubricated.

[GreenWood]

The "rivet" is likely solder where silver is brazed through a hole in the spring.


Black is key, orange is spring, red is solder

I don't recommend, but you could file off the "rivet", prepare a new spring (which would have to be good enough steel or it will end up fatigued and not springy), and then with the lowest temperature silver based solder possible (because you do not want to melt the key) braze the new spring on. It is possible to do this at home with a small propane or butane torch, but I don't think you would want to learn how to on a key. A jeweler would do this for you easily if you presented him (or her) with the material and instructions. I like your solution though






Your images do upload to the page, you just have to open the image in your link till it ends with jpg, then paste that into the nescessary brackets.

[Terry McGee]

There are a number of things that could go wrong in attempting to braze the spring to the key. The key could melt (unlikely unless you really overheated it), or, if it turns out to be made in two pieces (cup and shaft) unsolder at that joint. Also hopefully not likely to happen, but possible. But I'd worry about losing the temper of the spring material. Brass or its alloys would certainly soften too much, but I'd fear that even spring steel would be likely to.

I have done emergency repairs by soft soldering a brass spring back into place, using lead-based electronics solder. But it leaves a mess for others to clean up later. You don't want the lead in the solder to migrate around to the visible sides of the key, and lead loves flowing over silver! Conceivably, an epoxy glue might be strong enough to hold the spring in place, especially if the rivet end of the spring was cut larger than normal to give more surface (gluing) area. And perhaps domed a little to fit the inside curvature of the touch.

I would approach the job the old fashioned way, but I'd be happy to hear alternative suggestions. I'd flatten the stub of the old rivet by filing, centre punch the centre of it and drill right through the key touch at the size of thick silver wire I had available. Then, using jeweller's (not plumber's!) silver solder, solder a short length of such wire into place to act as a new rivet. I'd roughly file off any excess on the touch side, file the rivet to the right length, prepare the replacement spring then rivet it in place. I'd then get the spring working to my satisfaction, then return to smoothing off the touch side (it tends to get a bit flattened in the riveting process), and polish the whole key back to "as-new". It should be an invisible repair. Then repad the key and make any final adjustments to the springing, and then glue a patch of cork under the touch to stop the key from clicking on the wood.

I think any competent silversmith could manage the old fashioned way, but it's a bit of an ask to expect them to get the springing working right, and to manage the repadding and corking!

I have seen flute key repairs where, instead of soldering in a new stub for rivetting, the top of the hole is countersunk, the wire is rivetted on both sides, and then the top smoothed. Hard to make the top look perfectly smooth, but such repairs can work mechanically.

And I've seen repairs where the rivet is replaced by a tiny screw, tapped into the touch and screwed up from below. This needs to be filed off at the top and smoothed, but being steel it's always visible as a little grey dot.

[an seanduine]

Here is a possible repair suggestion. . however I must hasten that this suggestion is speculative. I am always trying new materials as they become available. In the past 10+ years the Dental field has seen seen the deployment of a variety of UV photo-sensitive hardening resins. I recently became aware that some analogues of these resins have become available for home repairs. The resins do not ordinarily harden/bond until they are exposed to certain UV light frequencies. . .then they ''kick'' after a brief exposure. . .5 to 8 seconds. Here in the States it is marketed under the name Bondic. Just like the introduction of cyanoacrylate glues, there are now several competitors of varying quality.
It might be possible to put a dot of this on the underside of the spring and have it bond through the rivet hole to act as a 'mushroom'
rivet head. The strength and bonding ability of these resins is impressive. It holds up to the rigors of chewing and when used as a 'filling' material compares well with the calcium apatite that makes up our teeth. It is machinable and can be shaped with abrasives after hardening. It bonds to a wide array of non-oily surfaces and can be built up in layers. It is not overly expensive and may be worth a shot.
My tuppence from the fringe.

Bob

[GreenWood]

@ Terry

The only reason I thought it might not be riveted is that any play at all would gradually wear out the hold...but that is a guess on my part..brazed should give a firm hold ? I don't have much practical experience at riveting so concede to whoever does.

When brazing it is the area around the join of the key (in this case the whole key because silver transfers heat fast, and especially if thick) that reaches temperature, as well as the steel at point of braze. Steel conducts heat poorly, and it is also common to cool areas of a work (by various means) to avoid various effects, so I don't think the spring itself need be affected. It is really for a jeweler or someone with experience though, because there are a hundred details worth knowing.

My thought on what I would do without heating was also to bolt it on. I would use two small bolts along the axis, would drill pilot holes that did not surface on the outside of the key, tap the spring and holes, loctite in two small bolts, then file flat.

[david_h]

And I've seen repairs where the rivet is replaced by a tiny screw, tapped into the touch and screwed up from below. This needs to be filed off at the top and smoothed, but being steel it's always visible as a little grey dot.

The springs are fitted that way from new on my Burns flute. What took me longest in replacing a spring was finding a source. A flute fettler of this parish (thanks jemtheflute) directed me to a source so I bought a bunch at less than 1USD each to allow a choice of pressures and in case I work hardened my first attempt by fiddling with it too much. I had to scrape across by the hole a tiny bit so that the screw came flush on the top of the touch. A lighter spring I tried would have needed a shim.

I would have thought a woodwind technician could tap the hole. Or if not then a clock repairer - who could probably find or fashion a spring as well.