 The Clarinet BBoard
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Author: Jazzy04
Date: 2004-11-05 13:35
hey everyone...
just wondering if anyone else has had this problem. in extreme heat... my rc prestige's corks seem to swell... which is a normal thing to do right?? what then is bizarre, is that no matter how greased the corks are... the rings that are meant to stop the clarinet getting stuck together, MUST expand when they are inside another joint... so my clarinet gets stuck and i cant do anything except keep my clarinet in air con for a couple of hours...
help??? what do i do... its really annoying...??
thanks heaps
jazz
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Author: John O'Janpa
Date: 2004-11-05 14:24
I'm sure the rings do expand slightly when they are heated, but I suspect the wood, in the socket the rings go into, is expanding even more due to absorbing moisture, and being warmed. Sometimes, if you are pulling the joint for tuning, using tuning rings will decrease the amount of moisture getting into contact with the wood in the socket.
If tuning rings don't help, and this is a recurring problem, a technician can carefully remove a small amount of wood from the inside of the socket.
If the instrunet is new, see if it can be done under warranty.
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Author: Ken Shaw ★2017
Date: 2004-11-05 15:30
As John says, the swelling is 99% certain to be iat the deep end of the barrel's lower socket. When cork grease doesn't solve the problem, then it's wood binding against wood, the top of the upper joint tenon against the barrel socket.
This can lead to cracks in the upper joint and should be taken care of immediately. It's tempting to file down the top of the tenon, since it's easy to get to, but this loosens the joint if you ever change barrels. Go to the trouble to ream out the socket. That way, all you can ruin is the barrel.
Best regards.
Ken Shaw
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Author: Bart Hendrix
Date: 2004-11-05 19:25
Expansion of the wood in the socket (likely) would have to be from moisture effecting the fibers of the wood. Physics dictates that thermal expansion of the material around a hole causes the hole to get larger -- not smaller.
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Author: BobD
Date: 2004-11-05 21:05
"Physics dictates that thermal expansion of the material around a hole causes the hole to get larger -- not smaller".......
Hmmm......I wonder!! For some reason that doesn't seem 100% true. Just what physics are we talking about? Do you suppose the wall thickness is a factor?
Bob Draznik
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Author: Mark Charette
Date: 2004-11-05 22:12
BobD wrote:
> For some reason that doesn't seem 100%
> true.
It is, and it's true for any ring as long as the coefficient of expansion is positive (which is true for most substances we're familiar with. There's one major exception, but you'd have a heck of a time making a clarinet out of it if you expected the instrument to last past a cold winter ...  )
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Author: BobD
Date: 2004-11-06 12:50
Thanks, Mark, guess I was having a senior moment...
Bob Draznik
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Author: Gordon (NZ)
Date: 2004-11-06 14:15
Mark, all my physics/mechanics education says the same thing, agreeing with you.
However timber, perhaps because of its tubular construction and perhaps other properties, may behave differently.
I had to consider this serious when a forum writer pointed out that if I drill a hole through timber, such that a rod fits freely through the hole, then the rod will jam after the timber is soaked in water. I think it will come free again after the timber has dried out, although once surface fibres have been wet they seem to be raised, making the surface rougher.
It is possible also, that when the timber tube expands within a restricting metal ring (which has insignificant relative expansion), it does tend to expand into its bore. I'm not sure.
However, I have noted that mouthpieces never jam in barrels, suggesting that it is only a timber TENON that jams,, rather than the socket. The other writer's response to this was to state that mouthpieces are always a looser fit than other tenons. I'm not sure about that either.
I once measured the ID of a tenon socket of a barrel, and then soaked the barrel for days under water. On re-measuring, I could detect no reduction of ID.
BTW most tenon sockets are not cylindrical. They tend to be narrower at the ring end. I guess this is a result of either slight oval distortion of the open end during machining, or compression of the timber when the ring is jammed on.
Interesting topic.
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Author: Mark Charette
Date: 2004-11-06 14:52
Gordon (NZ) wrote:
> I had to consider this serious when a forum writer pointed out
> that if I drill a hole through timber, such that a rod fits
> freely through the hole, then the rod will jam after the timber
> is soaked in water.
Is that true, or is it what someone told you?
Also, the physics formula holds true where the coefficient holds true in a homogenous substance; in cases of inhomogenous substances, including wood, it's positive in varying degrees depending on orientation. That causes warpage and could possibly explain what the rod gets stuck, if indeed it does.
> It is possible also, that when the timber tube expands within a
> restricting metal ring (which has insignificant relative
> expansion), it does tend to expand into its bore. I'm not
> sure.
Again, the physics works for a material free to expand. If you stop the expansio other things will happen; whether or not it actually changes the bore dimension or just increases the internal stresses would really depend ... and I don't know the answer ...
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Author: Gordon (NZ)
Date: 2004-11-06 21:01
"Is that true, or is it what someone told you?"
Somebody wrote it, but it is true to the memories of my own experience assembling framing for support of my kiwifruit vine. Of course memories are unreliable.
"...in cases of inhomogenous substances, including wood, it's positive in varying degrees depending on orientation. That causes warpage and could possibly explain what the rod gets stuck, if indeed it does."
Yes, perhaps the 'hole' gets a bend along its length, causing the jamming.
"...whether or not it actually changes the bore dimension or just increases the internal stresses would really depend ... and I don't know the answer"
Me neither.
Note that if you sand some timber smooth, then wet it and dry it, it will no longer be smooth. This effect could be another parameter affecting timber but not other materials.
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Author: BobD
Date: 2004-11-07 16:13
I take it we are making a clear distinction between thermal coef effects and dimensional changes due to moisture content. Surely both can be interacting in some instances.
Bob Draznik
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Author: BobD
Date: 2004-11-07 16:17
p.s. looking at the title again.....and not being familiar with the Presitge.....where do the copper rings occur?
Bob Draznik
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Author: Mark Charette
Date: 2004-11-07 16:35
BobD wrote:
> I take it we are making a clear distinction between thermal
> coef effects and dimensional changes due to moisture content.
> Surely both can be interacting in some instances.
Yes, but if both are positive then then any ring, no matter what the material, will expand.
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Author: Gordon (NZ)
Date: 2004-11-07 21:03
With metal and grenadilla, I would suggest that THERMAL expansion is so small as to be irrelevant.
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Author: Jazzy04
Date: 2004-11-08 05:30
the copper rings on my prestige are meant to STOP the joints getting stuck together in the heat... they are around the inserts (i dont know what they are called... the bit that goes into another bit) on the top and bottom joints (the keyed joints only)
thanks for all the suggestions
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Author: Jazzy04
Date: 2004-11-08 05:31
ps... i have no idea what everyone is talking about in terms of thermal expansion and so forth... but thanks anyway!!!
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Author: Gordon (NZ)
Date: 2004-11-08 09:29
"Thermal expansion" is expansion(i.e. getting larger) on account of an increase in temperature.
The "copper rings" are probably brass (if they have a definite yellow look) or "nickel silver" (if they have an almost silver look). Copper has quite a red colour.
The "bit that goes into another bit" is called the "tenon". It has a cork on it. It goes into a "tenon socket", sometimes called a "tenon receiver".
"the copper rings on my prestige are meant to STOP the joints getting stuck together in the heat... " Almost correct. They are supposed to stop the joints getting stuck when the timber absorbs moisture - not heat.
If the joint is jamming then it means that perhaps it was made with too much precision. That is a lot better than being too sloppy!
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