 The Clarinet BBoard
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Author: Karel
Date: 2003-03-26 08:05
Recently the screw that holds the R hand C key of my R-13 has fallen out twice, fortunately I was able to find it. What would be a simple and safe way of prevening recurrences please?
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Author: Gordon (NZ)
Date: 2003-03-26 11:04
It depends on the type of screw. Some need to be screwed hard in until the head seats. For some very similar-looking, headed screws, screwing it hard in will do serious damage. Sometimes a locking fluid is needed in the thread. That is why you get it attended to appropriately by a good technician. If you personally have sufficient mechanical nous to safely deal with this, then you probably would not have needed to ask the question.
A loosening screw can often be a symptom of a quite different problem.
Right hand C key??? That almost always has a long shaft, usually also holding on the Eb key. It does not "fall out". Several notes stop playing long before this shaft falls out.
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Author: LBViola04
Date: 2003-03-26 12:02
A very easy solution to this problem is to drop a small drop of clear nail polish on the head of the screw.
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Author: Karel
Date: 2003-03-26 14:43
Gordon, my mistake, I meant the L hand "C" key. What falls out is quite a short screw from the upper end of the "C" key assembly, with a sharply pointed end. If I screw it in (gently) as far as it will go it prevents movement of the key. If I loosen it slightly to allow key movement, the screw over a matter of a few days works its way out. My nearest technician is 400 Km away and unless really necessary, I try not to send the instrument away; when I go to the city, I take it with me for a "check-up". I do not see this as a complex mechanical problem since I can reassemble the mechanism easily enough, I was looking for advice on how to stop it from happening again, without causing other problems. I have heard of using nail polish but have no idea what locking fluid is, or how safe it is to apply.
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Author: BobD
Date: 2003-03-26 16:00
Probably the most common thread locking fluid is a product called "Lok-Tite" which you can find in the automotive section at any store. You apply this to the threads. My personal preference based on what you report would be to insert the screw as you usually do and apply nail polish over the head area and the end of the post. Gordon is usually "on target" with his analyses.
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Author: Gordon (NZ)
Date: 2003-03-26 22:53
If the screw is of the pointed type with a head, then ideally the end of the key should be appropriately counter-bored (special tool) to accept it without jamming.
However some screws like this are not actually designed to go right in - cost-cutting manufacture, but easier adjustment should this be necessary.
If the screw has a head and a cylindrical pivot end, then either this end is too long, or it is slightly bent. Often a tap on this end of the key with a soft hammer will stop the jamming.
The band-aid fix for both of the above is to use Loctite, available from hardware or engineering supplies. Unscrew the screw a little first, apply to thread, and then correctly position the screw. It wicks through the threads and within minutes, sets to a plastic.
YOU MUST NOT USE JUST ANY LOCTITE!! There are many varieties. Most are designed to set very hard, and a pivot screw would break before it came out again. The type you want is called "222". It holds small screws securely but still allows adjustment. "242" is firmer, and you could also get away with that.
If the screw is of the type with no head, then Loctite is definitely the answer.
Next best is nail polish on the slotted end of the screw. Nail polish snaps apart when adjustment is attempted, and typically secures only the end of the screw, often allowing the pivot part of the screw to wobble if the threads are 'sloppy', which is very likely if it works its way out.
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Author: Hank Lehrer
Date: 2003-03-26 22:56
Hi Karel,
I expect that your confusion with the RH and LH is a part of living "down-under."
HRL
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Author: Karel
Date: 2003-03-27 00:59
Cheers Hank,
Actually I was holding the darn thing upside down and forgot to apply double conversion before posting.
KV
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Author: Karel
Date: 2003-03-27 01:02
Thanks guys, and especially Gordon, for the detailed advice. It is a headless screw so I will use Locktite 222 as instructed, and later take it down to Perth to the "specialist".
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Author: Wes
Date: 2003-03-27 04:58
While on the subject of the LH c/f key, does anyone have suggestions on how to take out loose motion on the lower end of this key? It's hard to swedge this key. Unfortunately, they don't make it long enough to be easily swedged. Maybe, Gordon would be so kind as to comment on this.
Thanks a lot.
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Author: Gordon (NZ)
Date: 2003-03-27 10:15
Use some 'down under' ingenuity. Suggestions:
1. Use a washer. Some suppliers provide polymer ones for this purpose. I have never used one.
2. Grind away some of that surplus metal so that there is a cylindrical part of the pivot tube, and swedge the the key in that area.
3. Solder an extra piece of tube to the end of the tube. Rather, solder on an extra piece of rod, and then drill through it.
4. Solder (using 95/5 tin/silver which is reluctant to corrode) or silver-solder a 'blob' (of solder) at the end of the pivot tube, shape it, and drill it.
5. Similar to 4, but use superglue instead of solder.
I have successfully done 3 and both versions of 4.
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Author: BobD
Date: 2003-03-27 12:48
Gordon......thanks from me too. Reading your comments is always informative and one of the high points of my daily bb visit. BobD
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Author: Donn
Date: 2003-03-27 13:47
Whatever liquid you use, remove the screw and dry any oil first.
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Author: Gordon (NZ)
Date: 2003-03-28 07:55
Thanks, BobD.
Actually I'm looking forward to losing this information-sharing addiction, and moving on to another passion.
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Author: Wes
Date: 2003-03-29 06:32
Gordon--Thanks for your excellent comments. When I get moved from Torrance to Redondo Beach, CA next week, maybe I can try one of them. It would be good if the manufacturers could address this on new clarinets.
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