 The Clarinet BBoard
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Author: john cole
Date: 2001-04-23 05:48
I have a Yamaha wood clarinet with frozen bis-Eb/Bb key (the banana key between 2nd & 3rd LH finger holes). When the key is operated, the whole pivot shaft moves. You can see this at both ends. It sticks when pad fully opens, and closes sluggishly when opened a bit less. (Previous owner's solution: plug the tone hole with piece of cork.) I think it's rust. All other screws turn fine.
A screwdriver moves the whole key, so it isn't frozen threads. Penetrating oil did nothing. Forcing it would break the slot. I think a torch might damage the wood, ruin the spring, and probably do nothing to the rust. I've done repadding and I have freed a lot of screws so I can FEEL when something is stuck for good.
I think I need to locate a capable repair shop. But first I want your help defining "capable" . The least destructive way I can see would be to cut between the key tube and the post with a thin jeweler's saw , sever the steel pivot shaft, then rotate the other post slightly so the key can be pulled off the shaft. Then reassemble with a new pivot shaft.
I want to know the recommended approach before I let anyone touch it. Two questions--will a jeweler's saw cut steel ? Do pivots have a standard thread so they would interchange? (I've never lost one so I never had to replace one.)
Does anyone have specific suggestions or experience? Thanks.
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Author: George
Date: 2001-04-23 12:33
Two thoughts:
1) Often, penetrating oil (and there are lots of types, of different efficiencies) will often get into the joint much better if you warm the hinge gently with the side of a flame. You may want to try several sessions spread over a number of days - you are waiting for the oil to diffuse into the space, and diffusion is a slow process.
2) If you saw the pin, you will shorten the hinge tube to the point where it won't fit the space. If you did this, you would probably have to replace both the hinge pin (and its key) and the post which would also have been damaged by sawing.
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Author: Anji
Date: 2001-04-23 12:45
Don't screw around with this... the sliver keys are so close to the tenon that you could cause more problems.
This one definitely calls for the attentions of an experienced tech.
Pads and springs are one thing, this is entirely more complex.
Tap Dave Spiegelthal and John Butler for recommendations or appointments.
anji
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Author: Gordon (NZ)
Date: 2001-04-23 12:54
You can heat the pivot quite a lot - at least 100 C - with no problem for the timber. This allows penetrating oil to do its thing better, and normally the pivot frees far easier WHILE it is hot. By the way are you useing a large headed, long screw driver to push down hard and hold the pivot STILL while you rock the key. This way there is FAR less chance of damaging the head because thread friction is helping rather than being fought. A really appropriate screw driver is an indispensible, expensive, specialist item. The best I have used are from Kraus.
If you are very careful you can drill along the shaft at least the thickness of the post, from the threaded end of the shaft, with a drill, say 1.2 mm diameter. Then the key/shaft unit can be rotated as you describe, breaking through the remaining steel. I use a dental burr to go through the hole and further weaken the remaining steel if necessary. If a drill bursts out the side of the steel it will far prefer to 'wander' into the softer metal of the post and make a real mess of the post. Removing the remaining steel thread in the post is usually easy by screwing the appropriate tap or a screw through the post, or by using a 'broach' jammed through the hole.
Jewelers saws will cut steel, and they are available quite thin. However on the rare occasions I use the sawing approach I use a dental diamond wheel. These are available down to about 0.2 mm thick. After this cutting method the pivot tube will need 'swedging' to again fit neatly between the posts.
Different makes of clarinet use dozens of different threads, some very obscure indeed. Yamaha pivot threads are pretty consistent and 'standard' though. The shaft is probably 2 mm diameter and the thread is probably metric 1.7 mm x 0.35 mm pitch.
Pivot rods vary so much that I have found it preferable to stock the gear for quickly making them, including a huge range of threading dies, rather than trying to stock them. The stocks I do have from earlier repair days have a turnover of only about 0.5% per year!
The task you ask about really is a job for a good technician, but I have seen plenty jobs of this type that have been butchered by technicians. I would certainly research for a technician you can trust.
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Author: jbutler
Date: 2001-04-23 13:36
Patience......
Sometimes it takes awhile for the oil to work. I once let a frozen (rusted) rod on a clarinet soak for over a week. I kept applying nitro solvent and heat periodically. Finally, one day my trusty screwdriver backed out the offending rod with success. It was a very dark brown from all the rust! It doesn't take a lot of oil either. Don't use so much that it soaks the wood especially around the posts.
John
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Author: Willie
Date: 2001-04-23 19:42
I get a lot of wood winds like this because of the wet climate here on the Texas gulf coast. I've found that "Rust Eater" works good, but don't try to spray it on the key. Spray into a small container ( I use an old glass iodine bottle) and apply with a tooth pick or needle. I heat the key lightly and let the cooling process draw the penetrant inward to the affected area. This may take a few tries. If this doesn't work then look for a good (experienced) repair tech. I just did this last night on the octave key mechanism on a sax for one of the high school kids. Marching in the rain does terrible things to woodwinds.
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Author: Willie
Date: 2001-04-23 19:44
Forgot to mention that Rust Eater is sold at AutoZone stores.
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Author: Donn
Date: 2001-04-23 22:40
Ferree's sells an excellent penetrating oil they call "Corrosion Cracker" which has done a very good job for me.It will penetrate to an opening of only a few millionths.
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Author: jbutler
Date: 2001-04-23 23:59
Donn,
I have "corrosion cracker", but find that any nitro-solvent from a gun shop (Hoppe's/Outers/et.al) outperforms the "corrosion cracker" every time. I really prefer the "Rust Proof" brand.
John
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Author: ron b
Date: 2001-04-24 02:50
Corrosion Cracker is good but, personally, I second the recommend for Hoppe's.
Hoppe's, heat and patience will get it every time.
- ron b -
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Author: Gordon (NZ)
Date: 2001-04-24 14:06
Thanks for the tip, John. I have not been too impressed with "corrosion cracker" myself. I have heard raves about a product from mechanical engineers tooling supplies, but I've forgotten the name.
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