 The Clarinet BBoard
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Author: hans
Date: 2019-04-30 18:51
Earlier this month, I wrote about a Selmer N that I was considering.
I bought it and took it to my repair tech to put it in better playing condition, for the minor issues described earlier, but he found that the middle tenon (at the bridge) is worn and replacing the cork won't remedy the wobble at that joint. The excess play could have been caused, I suspect, by excessive/careless sanding during earlier cork replacement so that I'm looking for an effective way to remove the wobble.
Replacing the entire tenon looks like very major and specialized surgery for a 70 year old instrument (although it is otherwise in good condition, IMO), but dental floss or teflon tape wrap seems too temporary.
I was wondering if the heat shrinkable tubing used by electricians might work and be more durable, if any BB members have tried it, and if so, was it successful.
Alternatively, has anyone tried lining the joint mortise with thin wood veneer (I have some teak veneer) to tighten a joint?
Thanks for any suggestions or comments.
Hans
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Author: John Peacock
Date: 2019-04-30 19:19
Hans: I have had some success in fixing wobbly tenons using superglue. The problem is usually that the wood below the cork is worn - i.e. the "shoulders" are rounded rather than square and sharp edged. They need to be built up again so that they match the dimension of the socket at the top of the lower joint. You can achieve this by putting a drop of superglue where the shoulder should be and rotating the joint while it is horizontal, so that gravity pulls the glue into a continuous ring of superglue around the bottom of the tenon. This can be repeated until you have the desired size. If you overdo it, it's easy to file down the excess. It doesn't take much of this to cure the wobble, and the result seems permanent - i.e the superglue is about as hard as the original wood. It's not even that obvious to the eye that anything has been done.
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Author: Tony F
Date: 2019-04-30 19:19
I've never tried it myself, but I once saw a clarinet centre tenon that had been lined with a very thin metal sleeve to fix this problem. The metal used was thin brass shim. I don't know what thickness was used, you'd have to do some careful measuring to work that out.
Tony F.
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Author: kdk
Date: 2019-04-30 20:28
I've seen the brass tenon caps that Tony refers to. I'm not sure there haven't been some clarinets that were manufactured with them. They seemed to work well. I have an old R-13 from the 1950s that had become wobbly in the middle, and my repairman simply mounted a new cork that extended all the way down to the end of the tenon, covering the wood shoulder. It still does a good job of stabilizing the joint - although on an instrument in regular use it probably would need to be redone periodically. It isn't the clarinet I regularly use, so it hasn't had much stress put on it since the repair was made.
Karl
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Author: Ed
Date: 2019-04-30 23:04
I have seen the same as what Karl mentioned (extending the cork). It works well and is an easy fix
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Author: hans
Date: 2019-05-01 00:41
Thank you all for the superb suggestions. It was very gratifying to have so much creative help so quickly. I have asked my repair tech to do what seems like the simplest repair first; i.e., extend the cork. Like Karl's, this is not my main clarinet so that a less durable repair should be adequate for my needs.
Best regards,
Hans
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Author: MichaelW
Date: 2019-05-01 23:30
Attachment: Nach Überholung.jpg (466k)
Frank Meinert, Markneukirchen, in 2012 did a general overhaul with my F.A.Uebel 8642 from 1936 and strengthened the upper joint upper tenon with epoxy. It is in good fashion since then (photo).
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Author: Chris P
Date: 2019-05-01 23:32
I build up ill-fitting tenons with superglue and wood dust, then machine them down so they fit the socket like a tuning slide on a brass instrument.
They should be a rock solid fit in the socket even without the tenon cork fitted - the tenon cork is there to create an airtight seal as well as applying the outward force within the socket to ensure the joints stay together.
Also make sure the upper tenon ring (by the shoulder) is made much wider than they usually are as that will guarantee far more stability than a narrow tenon ring.
Just adding more cork isn't going to cure the problem and can ultimately cause more harm if it's too thick and exerts too much pressure within the socket.
A wobbly tenon can also cause harm as it will put undue pressure on one side of the socket when it's at an angle and in a worst case scenario it too can crack the tenon down the front and the crack will run into the C/G tonehole.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: clarnibass
Date: 2019-05-02 16:38
>> machine them down so they fit the socket like a tuning slide on a brass instrument. <<
At least here, if I machine them to that fit, they would get very resistant, if not impossible to assemble and disassemble by the player, as soon as they play or weather changes. Even a looser fit than that, by not enough, can make the tenon too tight part of the year, or with enough playing.
Most of the time I use the method Chris described. I've never had a problem with it. Sometimes it can even save a significant amount of time since the cork doesn't have to be replaced (if it's good).
I've made sleeves but it takes longer and after more than a few, I think it is rarely necessary. If it's for the inner shoulder the cork would have to replaced too.
I've also done the metal tenon rings, using both silver and brass (I prefer silver). It just takes longer and I don't think it's better really, so more often than not it's not worth the effort.
>> Replacing the entire tenon looks like very major and specialized surgery <<
...and completely unnecessary for a loose tenon. It's like replacing a panel on your car because of a scratch This is only necessary when a tenon or socket break off, and even then in some cases it's not.
A heat shrink tube is likely to peel the moment you assemble it and almost certainly is too thin or too thick anyway.
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Author: Steven Ocone
Date: 2019-05-03 20:32
I have taken some thin silk cloth (from a torn swab) and glued it on to the end of then tenon with super glue. Then made sure the outside was coated with super glue. Then trimmed the excess and filed it down. It's similar to the super glue methods - helpful if there is a lot of space to fill.
Steve Ocone
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Author: hans
Date: 2019-05-08 21:46
Attachment: Brass shim repair.JPG (115k)
I retrieved my repaired clarinet today. The repaired joint is tight and it plays well so that the brass shim repair was successful.
Thank you again to everyone for their comments and suggestions.
A picture of the repair should be attached.
Hans
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Author: clarnibass
Date: 2019-05-09 06:55
Using a metal shim, it is usually attached to the tenon and not the socket, because almost always the tenon wears a lot more than the socket.
Is that stuff smeared near the top cork grease or some left over epoxy from the gluing?
I guess that darker area on the right is the brass ring joint? Is it smooth and completely filled, just the photo and colour make it look lower? If there is a gap or channel there it can cause a leak. You could feel that by play testing, but some leaks are hard to notice, it would still feel fine until the leak is fixed and it then plays better.
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Author: hans
Date: 2019-05-09 07:19
It did seem counterintuitive to line the mortise instead of building up the worn tenon but it was left to the technician to decide on the best way to solve the problem and he has decades of experience.....
The smear is indeed cork grease; the cork is new and I applied a bit more than necessary when I tested it.
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Author: clarnibass
Date: 2019-05-11 07:45
The extra cork grease makes it look uglier than it is... but there are issues to consider... that the top is smooth and won't peel/grab the cork, and that the joint doesn't have a channel that might tear the cork or even leak.
Other than maybe looking nicer, there is no real reason to have a metal sleeve cover the top of the socket, as long as there is no edge there to grab the cork.
I almost never shim the socket because the wear on tenon and socket joints is usually more at the tenon side. Also the two shoulders of the tenon don't wear evenly (the outer end often much more) so I build up each separately.
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