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 Excessive Slack in LH C/F Key (YCL 72)
Author: LJBraaten 
Date:   2014-03-03 10:28

Edit: the problem has been fixed, see my Apr 18 post.

I own a few clarinets, but none of them has the excessive slack in the left hand C/F key as found in my Yamaha 72. The key depresses nearly to the body of the clarinet as the cork on the key mechanism wears and compresses with age. I can get by with it unless I have to play a fast passage, then I either can't depress the key quickly enough to get a clear note, or my finger slips off the key. New cork solves the problem for a few weeks, but after that I am once again fighting the slack.
Has anyone else had this problem, and if so, how did you solve it? For those not familiar with this model, the long shaft on this LH key turns a cam which strikes a flat lever on the shaft attached to the key on the lower body. This flat area has thick cork on it, but as mentioned above, it begins to depress quickly and the slack returns.
I've had two good repair techs look at it. One said that it looks like this is a design flaw since the upper lever appears to be too high (which makes me wonder if a replacement part might be the answer). Both techs are hesitant to try to correct it by bending. One said he could try to carefully solder a piece on it to make it thicker, but it would be risky. I wonder if I could get the same results by gluing a thin piece of hard material on it (Twice I've tried stick-on Teflon to make the lower cam thicker, but it eventually works loose and gums up the mechanism). The other tech suggested that he add an adjusting screw to the upper foot, like he has on one of his clarinets. This would eliminate the need for cork. So far this seems to be the most appealing option, but I wonder if there might be other solutions.
I would be interested in thoughts or opinions by those that have tackled a similar problem.

Laurie

Laurie (he/him)

Post Edited (2014-04-18 23:17)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: donald 
Date:   2014-03-03 11:07

Check out the reccent post "another buffet botch up". At first it might not seem relevant- but some of the postings include photographs of the solution your tech suggests
dn

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: Gordon (NZ) 
Date:   2014-03-03 14:29

For any Yamahas I work on where the F/C lever (the left hand-operated part) has chewed through the linkage cork on the F/C key (right hand operated part), i.e. most of them eventually, I do the following:

- Solder (using 95/5 tin/silver solder for tarnish-resistance) a strip of 0.4 mm thick sterling silver sheet under the linkage surfae of the key, and trim & polish it so it is barely detectable.
- SLIGHTLY round off the sharp edge on the lever (that operates the key.)
- "Cork" the new surface of the lever with 0.35 mm thick, incredibly tough, low friction, "microfibre", synthetic leather pad material used on one of the top models of sax pads made by Music Center (previously Pisoni). An inferior substitute would be 0.4 mm "techcork".

Result: fantastic, clean action. Problem solved for the life of the instrument.

This is one piece of design that Yamaha botched up and has not put right. At least it is easier to correct - about 10 minutes - than the Buffet version!

For the much worse Buffet Botch-up in the same location that I wrote about in the other thread, I have just got the clarinet back and soldered in not a bit of sheet metal, but a carefully shaped wedge of sterling silver. Very successful, but quite time consuming to get the taper and thickness right.



Post Edited (2014-03-03 09:32)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: LJBraaten 
Date:   2014-03-03 16:35

Thanks Gordon, that is very helpful! I hope you don't mind if I pass along your post to my repair tech.

Laurie

Laurie (he/him)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: RAB 
Date:   2014-03-03 17:37

There is a synthetic material, Tec-Cork, that is very dense and does not compress. I would try putting that on the C/F lever where the left hand pinky key strikes when it is depressed. I would leave enough room to put a med thin piece of Teflon sheet on top of the Tec-Cork. I use the Teflon that is etched on one side so it will accept contact cement and not fall off. These products can be purchased from JL Smith or Music Medic. I am sure there are other sources but these are ones that I use.

Hope this helps

Rod

Rodney Berry
Repair Dept
Muncy Winds Music Company
Boone, N.C.

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: LJBraaten 
Date:   2014-03-04 03:38

Thanks Rod, that sounds like at least a good temporary solution that will buy me some time until I can get it into the shop. If it holds up I may just stick with it.
Just found a bunch of other stuff I "needed" at Music Medic, oh well.

Laurie

Laurie (he/him)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: Gordon (NZ) 
Date:   2014-03-04 17:21

Yamaha actually already uses that tech-cork, or an almost identical product under a different name.

I make my modification because the lever quickly chews through that "techcork".

I have little confidence in a teflon laminate helping. It, too, is a quite "chewable" material.



Post Edited (2014-03-04 17:22)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: Chris P 
Date:   2014-03-04 18:14

Yamaha call it "Hycotex" in their repair manual.

Former oboe finisher
Howarth of London
1998 - 2010

The opinions I express are my own.

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: Gordon (NZ) 
Date:   2014-03-04 23:59

It is of a slightly more refined nature than that which other sellers typically sell.

There is a wide variety of this stuff manufactured and sold for the industrial gasket industry, eg gaskets for oil-filled transformers.

That was my source for top quality material about 40 years ago, long before I saw it used by others on instruments. I still have bulk of this and most of it still has no sign of the plasticiser leaching to the surface that renders substandard look-alikes useless for glued applications.

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: LJBraaten 
Date:   2014-04-18 23:15

I am pleased to report that the problem has been corrected, kudos to Gordon for posting the helpful repair tip.
I asked one of the repair techs I know to look at Gordon's post. He said he liked that fix better than his own suggestion (install an adjustment screw), and he would be glad to do it. The only variation is that since he has silver plating equipment he soldered in a piece of brass (instead of silver sheeting) then plated it. I have looked hard and cannot detect the repair. But more importantly, the lever now works like it should, there is no excessive slack, and I don't have trouble with fast passages (at least none that I can blame on the keywork  :) ). The repair guy liked it so well that he is going to the same thing on his Bundy Bass clarinet.

Again, a big thanks to Gordon!

Laurie

Laurie (he/him)

Post Edited (2014-04-18 23:16)

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 Re: Excessive Slack in LH C/F Key (YCL 72)
Author: tictactux 2017
Date:   2014-04-18 23:43

a more temporary solution may be using rubber-backed teflon (often used as furniture feet). The rubber backing is actually quite stiff, and I've used a thusly modified RH F/C on my Bundy Bass, and it's still doing fine after five years of regular use.

YMMV, but at least this fix is easily undone if it doesn't work.

--
Ben

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