 The Clarinet BBoard
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Author: David Lee
Date: 2009-09-21 15:58
I play on a Buffet R13 and do minor repairs myself. It seems that every three to six months I have to replace the small cork pad on the C key that is actuated by the rocker on the LH key. It seems to be a glue problem as the cork while a little beat up is still intact but has come loose. I am using contact cement that came with a clarinet repair kit I bought. I am letting the glue set for 10 minutes before putting the cork pad on and I rough up the key a little with emory. Is there a better material than cork for this little pad? Suggestions please.
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Author: tictactux ★2017
Date: 2009-09-21 16:08
I use rubber-backed teflon or cork, and either hot-melt glue or superglue. (when using hot-melt glue or shellac, be sure to sufficiently heat the metal so the glue melts on the metal, else it won't last).
IME contact cement doesn't really do well with tiny surfaces, especially metal. It's great for cork on tenons, but not for silencing keys.
(edit: replace "thoroughly" with "sufficiently")
--
Ben
Post Edited (2009-09-21 16:13)
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Author: Chris P
Date: 2009-09-21 16:33
The linkage on these isn't the best design, and the choice of silencing material is important for it to function well without being too spongy or too noisy - there's too much of a gap between the linkage so the underlever from the LH lever can chew into and through the silencing material on the underside of the RH F/C linkage. You want a tough material that won't compress or break, though still retains silencing properties. Natural cork is no good as it compresses too easily under such conditions.
Make sure the gap between the LH and RH parts of the linkage are parallel when at rest and find a suitable hard wearing material of the same or similar thickness to fit the gap (better being too thick than too thin) such as hard leather or 'tech cork' (high density gasket cork) - you can check the thickness by 'dry fitting' it to get the thickness right.
The cork bumber glued into the body under the LH F/C underlever will most likely compress if it still happens to be too thick, so that will save a lot of hassle having to sand things down once the silencing material has been glued in place.
Then once you have the thickness of the material right, remove the F/C key, remove any adhesive on it and thoroughly degrease the linkage thoroughly with solvent or alcohol before glueing the silencing material onto the underside of the linkage. Use a good impact adhesive for this.
I've even seen clear plastic trimmed from a reed holder used in this linkage on Buffets, it makes the action nice and snappy but creates too much noise.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LesterV
Date: 2009-09-22 17:24
I had the same problem with my R13 - the cork would permanently compress, forming a notch that caused problems. After having to replace the cork several times, I gave up on cork (including synthetic cork) and experimented with several other materials - finally going with PTFE filled Delrin held on with superglue. I cut a piece that was slightly too big, glued it on, then trimmed it to size with a sharp blade This material is available in .020 inch thick sheets from McMaster-Carr over the internet. This seems to be the ideal thickness and required no adjustment.
The problem is caused the sharp corner that presses against the cork on an R13. My old Selmer CT uses a similar linkage but has a rounded corner rather than a sharp one and has never been a problem. I sometimes think Buffet has a reverse learning curve when it comes to instrument design.
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Author: LesterV
Date: 2009-09-22 18:58
The 0.020 inch thick Delrin material I mentioned in my previous post is difficult to find by searching the McMaster-Carr on-line catalog <www.mcmaster.com>
Use the catalog number 2636T11 to find it on the first search.
The material's description is PTFE-Filled Delrin strip. It is 1 inch wide and the shortest length sold is 5 feet @ $1.29 per foot. Probably a lifetime supply for most techs.
In their printed catalog, page 3533, it is listed as Ultra-Wear-Resistant PTFE-Filled Delrin. This page can be viewed by clicking on "catalog page" on the left side of the screen after searching for 2636T11.
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Author: Chris P
Date: 2009-09-22 19:29
The gap between the linkage should be small (say between 0.5-0.7mm) and parallel to get the best action, and the silencing material filling this gap completely should be hard wearing.
But only few and far between instruments have this critical gap - others are most often too wide when they're made parallel, though increasing the thickness of the key cork on the LH F/C lever foot will tip it so the end of the underlever is in contact with the linkage from the RH F/C key - it may not be parallel anymore, but contact between the underlever tip and the underside of the linkage will be achieved so the action doesn't feel sloppy due to lost motion.
Provided the shape of the top side of the LH F/C underlever is good (in that it has a sightly rounded leading edge instead of being square) it won't chew through the silencing material on the underside of the linkage.
But this design is as old as Boehm system clarinets themselves and could be improved with some thought (at the moment it still employs such short levers due to the lack of space) - such as fitting a lever key like the other LH levers as Buffet do on their basset horns.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: clarnibass
Date: 2009-09-23 05:12
There are usually problems with the design of this linkage. There are a lot of options for materials to use there, and also other possibilities.
First about the shape of the linkage. Gordon (who also post on this forum) sent me a link showing the best shape for this linkage, it is of involute gear. See the animation on the right here http://en.wikipedia.org/wiki/Involute_gear
I haven't seen any clarinet with this shape. It is probably (maybe significantly?) more expensive to make. But a good design of sliding linakge is ok too. The main two problem like other mentioned are too big gap and a corner chewing into the material.
For the gap, it is possible to improve by adding a rigid material to the lever side. For example soldering a small piece from sheet silver or brass, or maybe even gluing it, or gluing some type of plastic (I've only tried the former).
Instead of trying to get around the sharp corner, it is possible to just shape it better. Just have to be careful exactly how to shape, and not too much. Rounding it too much could mean loss in the motion of the linkage and need to press the lever more. So just round it to not chew the material.
After the linkage is better, you have many choices for materials.
One method is drilling a small hole and gluing a small nylon rod into it. If you do this then it is important exactly where it is. Personally I don't like this method for several reasons, and prefer gluing a material.
Materials that I have seen or tried for this linkage are cork, synthetic cork, felt, rubber-cork (aka tech-cork), synthetic felt, leather, microfiber imitation leather, any of those alone or with very thin teflon glued on them, or (slightly thicker) teflon by itself.
IME the cork and felt are too soft, and I haven't found a synthetic cork that I like for this linkage either. I don't like teflon alone since I consider it too noisy. Leather is possibly good but I don't bother with it simply because the microfiber imitation leather I have is the same but better. So I use either that, or rubber-cork, or synthetic felt. Sometimes with and sometimes without thin teflon glued to it. I haven't decided that one of those is definitely better than the others since some are slightly more accurate but slightly noisier, and vise versa, and there are other reasons too.
I disagree that contact glue is not a good choice. I've tried about ten types of contact glue and they vary a lot. IMO it's very important to use a good type. I don't consider this too small surface for contact glue. For me contact glue is the easiest to work with and also I think it is more resistant and likely to last longest. I only sometimes use super glue for tiny surfaces e.g. steps of left pinky E/B and F#/C# levers. I never like hot melting glue for key silencing materials.
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Author: Malcolm Martland
Date: 2009-09-23 10:38
I agree with Chris P - it really is time to redesign this link but maybe not as an involute gear or even solenoid operated. I find that as I press the key down it moves to an awkward angle and my finger has a tendency to slip off - especially on hot sweaty days playing outside. I stick a fabric piece of elastoplast (or similar) on the key to reduce this problem.
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Author: Chris P
Date: 2009-09-23 12:35
On the early Buffet Elites (late '80s), they used a ball and socket type linkage - the LH F/C lever had the socket on the end (perpendicular to the key barrel - similar to the existing key foot but with a slot through it) and the RH F/C key had the ball joint connection where the linkage would normally be.
Though from what I've seen in subsequent instruments (that's seen and not touched) that design was short lived - maybe it felt too sluggish or maybe weighed or slowed down the action of the RH F/C key - though I'd like some insight on this from anyone that had an early Elite as I've never had the opportunity to work on any.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LesterV
Date: 2009-09-23 14:35
I don't understand the concern over noise from this linkage - but then my hearing is very poor above 4000Hz. I am sitting here with my R13's lower joint, operating the linkage being discussed, and the major noise source is the slap of the pad closing. If I hold the pad closed and operate the LH key, the noise from the linkage is barely perceptible - and this is with a large gap due to the pad being already closed, a condition that should generate the most noise. Of course, as I previously mentioned, I replaced the cork with the PTFE (Teflon) filled Delrin and my hearing isn't good. Does anyone with good hearing have a linkage that actually makes a noise that isn't dwarfed by the pad slap?
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Author: Chris P
Date: 2009-09-23 14:57
It's not the linkage that makes the noise when in use (that's using the LH F/C key), but the noise from the RH F/C key returning to rest (open) position that can cause noise when it contacts the LH F/C lever foot if the silencing material is very hard. Though this kind of noise is picked up when playing quietly or picked up by a sensitive and close microphone.
Though there are far noisier woodwind instrument mechanisms out there - mainly oboes and bassoons, so in recordings of Strauss, Mozart or Dvorak wind ensemble works played on modern instruments you'll always hear the clatter of keywork.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LesterV
Date: 2009-09-23 18:25
Chris,
Thanks for the explanation - it's not my hearing after all.
On my R13 there is a few thousanths of an inch clearance gap when the LH key is not depressed. The mechanical stop for the returning RH key becomes the crows foot which does make noise when either the LH or RH key is released. If the RH key did make contact with the LH mechanism when returning, I see that it would contribute to the noise as you have described, eliminating the noise from the crows foot.
My Selmer CT is set up so the LH key mechanism, rather than the crows foot becomes the mechanical stop for the returning RH key and the noise when the key is released is about the same as the R13. From a noise standpoint, there doesn't seem to be an distinct advantage of one way over the other.
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Author: Chris P
Date: 2009-09-23 19:12
On my old CTs I reversed the spring on the LH F/C lever so it was lightly sprung to 'open-standing' as it were (instead of being sprung 'closed') - the spring tension on the RH F/C key was set slighly heavier to be sure it returned and it didn't matter how thin the felt on the F/C lever foot was (but was there to prevent it clattering against the wood) or the silencing material on the RH F/C linkage.
In this way both parts of the mechanism were fully engaged at all times so any lost motion was eliminated, and when you closed the RH F/C key the LH F/C lever would move as if it was connected to the RH F/C key.
Though I later dropped this idea and sprung it in the usual manner.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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