 The Clarinet BBoard
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Author: David Lee
Date: 2005-09-11 17:47
I just recieved a used wood LeBlanc which I purchased from a web site offering refurbished horns. The upper joint top tennon has a metal cap, which has five cracks ditributed non uniformly around the cap in the portion which is fits tightly to the clarinet body tenon. They are about an 1/8" long (full height of cap)and do not penetrate into the top portion of the cap. My first thought was that they were designed that way until I noticed the non uniform spacing and under a magnifying glass they appear jagged. The cap is tight on the tennon. How important is this defect?
There is also a small ding on the inside edge of the tenon that fits into the bell, maybe a 3/32 inch wide 1/16 deep on the top blending into the horn cylinder on an angle of 45 degrees. This wouldn't bother me that much except that the site says that these type of things are repaired as a matter of course. This probably isn't a serious problem, right?
A leading restorer or used wood clarinets who did not supply this instrument states in their write ups on specific used wood clarinets
" tennons still sharp" are they referring to the inside dia or the outside. How important is this?
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Author: Chris P
Date: 2005-09-11 18:04
It's better the tenon caps are tight than loose, but here it seems the top joint has swollen up and cracked the metal tenon cap, as the metal is very thin on these tenon caps.
Or that the barrel had tightened up against the top tenon when it was still newish and the top tenon was turned down to fit (along with the metal cap), and the top joint has since swollen.
Without seeing the clarinet I couldn't tell you what the marks on the bottom joint tenon could be. As long as the tenons are sound, not too tight or too loose and don't wobble, there shouldn't be a problem.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2005-09-11 18:18)
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Author: Gordon (NZ)
Date: 2005-09-11 21:29
Multiple-split damage to tenons, and very likely caps too, is possible when the joint is mounted on a lathe and a large conical centre is used on the tail-stock. If this centre is wound in too far, then there is ample force available to result in multiple splits.
I have come across ex-factory, top-brand instruments where this is almost certainly what happened.
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Author: Chris P
Date: 2005-09-11 21:32
It can be replaced with a thicker gauge one (with a narrower inside diameter), but if it's not loose or binding against the socket, or even damaging the socket then it should be alright, but do keep checking it to be on the safe side.
Only way to tell if there's any underlying damage is removing the cap.
Has the top joint previously split and then been repaired at some point? Check between the top tenon and the two trill holes or the speaker bush for signs of repair work.
I've only seen tenon caps split around the circumference at the top before with maybe only one split running up the side, but not several splits running up the sides.
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Author: Gordon (NZ)
Date: 2005-09-11 23:01
I have not seen splits up the side before either.
I wonder if they were done deliberately by whoever installed the cap, because such person did not have a better means of forming flat metal into a cap.
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Author: Chris P
Date: 2005-09-12 09:05
Mind you, they're already work-hardened before they're fitted, and it's likely there's metal fatigue on the sides as these have had to stretch more during forming, I doubt they anneal them after being stamped and before fitting and finally turning down to size once they're on.
And as the top joint has swollen up, the splits happened.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2005-09-12 09:06)
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Author: Gordon (NZ)
Date: 2005-09-12 13:58
Hmm. I wondered about that, but then I thought about how the forming process actually puts the sides into compression... hardly a situation for splitting, which needs tension.
I actually make these form sterling silver sheet.
1. Select an appropriate thickness, to fill the gap between tenon and socket.
2. Cut a strip on my guilotine (or use scissors), a few mm wider than the tenon lip.
3. Aneal the strip.
4. Cut the strip to length, including a small overlap.
5. Taper off the overlap areas with a file and lap the ends together with silver-solder, to form a ring.
6. Gind off any excess metal where the lap is.
7. Coax the tight-fitting ring over the tenon lip.
8. Use a burnishing tool to form the excess width over the sides of the lip.
9. Adjust diameter if necessary (I use a linisher with a VERY fine belt, tidy up, and polish.
Sometimes I include epoxy glue between the metal and the timber.
It looks very professional.
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Author: BobD
Date: 2005-09-12 14:47
The jagged appearance of the cracks leads me to suspect stress corrosion cracking. Stress corrosion cracks occur when metal in a stressed condition is exposed to a liquid(or gas?) that contains ions the particular alloy is susceptible. Brass alloys, for example, in a work hardened state and exposed to ammonia can crack. If you have some Flitz brass polish around you will notice the label says, "contains no ammonia". You have not stated what alloy you believe the cap to be made of and I don't recall offhand the situation with nickel-silver alloy as recards SCC. IF someone tried to clean the metal tenon cap with an ammonia base cleaner/polish this could possibly explain the cracking.
Bob Draznik
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Author: Chris P
Date: 2005-09-12 20:01
That'll be nickel silver - I don't know if the later Leblancs used a thick, solid tenon tip ring that was half the thickness of the tenon wall, or if it was made in the normal manner from sheet metal, but the top only went half the thickness instead of completely covering the top to the bore (with the remaining wood being turned flush with the metal), I've never had to remove one of the later Leblanc ones to find out, though the '30s Buffets (w/artic. G#) had a sheet metal one of this type, the top of the tenon cap only coveing half the thickness of the tenon.
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Author: BobD
Date: 2005-09-12 20:08
"That'll be nickel silver "
That would surprise me as I've never seen nickel silver any color other than the dull gray appearance.
Bob Draznik
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Author: Chris P
Date: 2005-09-12 21:31
Dull grey?
I've only known nickel silver to be a very pale yellow colour when compared to brass.
Only cupro nickel (eg. Yamaha flute bodies) has a grey appearance that I know of.
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Author: Gordon (NZ)
Date: 2005-09-12 22:47
There are many variant of nickel-silver. For example the flute alloy used by Gemeinhardt is more yellow and far more likely to corrode than the alloy used for Yamaha flutes.
Some (most?) nickel silver, if it is freshly buffed, would fool most people into thinking it was silver. It is very shiny and quite white, like nickel-silver coinage when it is new. It gets more dull and yellow as it tarnishes.
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