 The Clarinet BBoard
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Author: kj2008
Date: 2015-06-19 21:26
I am curious what the purpose of this little screw is. I understand it is not supposed to be tighten up all the way. However, without out tightening up, I've noticed, time to time, it appears being moved by itself a little bit (by looking at the thread line) either direction (while there's still a little gap). Q1: What the reason for a little gap should be? Q2: Will the involuntary movement like I described of the screw, however small it was, impact tone quality or any adversary side effect from this?
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Author: kdk ★2017
Date: 2015-06-19 21:54
The G# key sits directly above the A key on a Boehm clarinet. When you play A, the G# key opens also, pushed up by the A key below it. The screw is meant to allow adjustment so the A key doesn't hold the G# up high enough at rest to interfere with closing the G# tone hole but without leaving a large gap that would cause lost motion when the A key is opened. The relationship between the two keys can be affected by pad thicknesses in either pad cup. In practice, it's much safer to leave a small amount of play so that the lost motion is minimal when A is played but there is no possibility of holding the G# key open when both are at rest (closed).
The plastic or nylon replaces the older metal screws, which required noise silencers (cork, leather, etc.) to prevent the metal-on-metal clicking that would happen when the A key hit the metal spacer screw in the G# key.
Karl
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Author: Paul Aviles
Date: 2015-06-19 22:50
and also,
If the screw is backing out more and more, it is possible to put in some "packing material" (ie a small piece of sewing thread) around the thread of that screw to prevent it from moving unintentionally.
And yes, you really want a little gap. Most pads will swell a bit with the changes of the weather and the presence of your condensation pouring down the bore. Since you cannot guarantee that both the "A" key pad and the "G#" key pad will swell to the same degree, the space will guarantee that you will not inadvertently generate a leak when/if the "G#" pad will not sit down all the way (as stated above) if the "A" key pad swells to a greater degree.
.............Paul Aviles
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Author: Chris P
Date: 2015-06-20 02:24
The tips of these nylon screws will benefit from being domed as they're often either square or have a worn groove in them, so mount the screw in a bench motor chuck and use 400-800 grit abrasive to dome the tip.
If the slot in the head has been mashed up by someone using the wrong sized screwdriver, then the screw can be replaced with a metal one with an M2x0.4 thread and a 2.4mm diameter head - Loree and Howarth oboe adjusting screws will do the trick but they will need to have the threaded end shortened.
And instead of having metal-on-metal contact which only creates noise or sticking a piece of cork or anything else in the slot on the A key which can wear out, drill into the tip of the screw and glue in, trim and shape a piece of nylon filament so it has a domed tip.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Jim22
Date: 2015-06-20 07:16
I have installed a styrene shim on the lower key on a couple of my clarinets that have metal screws. The styrene is still quiet but holds up better than the cork I found there.
Jim C.
CT, USA
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Author: clarnibass
Date: 2015-06-20 08:48
>> I have installed a styrene shim on the lower key on a couple of my clarinets that have metal screws. The styrene is still quiet but holds up better than the cork I found there. <<
Yes, cork is pretty lousy in most sliding linkages, especially with such a small contact surface that can dig into the cork. I usually use a type of synthetic leather for this linkage, if I don't use a plastic tip for the screw.
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Author: Steven Ocone
Date: 2015-06-20 16:53
If you continue to turn the screw in you will be opening the Ab key. You want to make sure the Ab key closes, with a tiny bit of play for security, in case of any changes in key play or pad thickness.
Steve Ocone
Post Edited (2015-06-21 23:30)
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Author: Chris P
Date: 2015-06-21 02:16
Some people check the adjustment of the throat G# screw by forcibly holding the G# pad cup down and making the adjustment with the pad held down. That in my books is a bad idea as that's only going to compress the pad which will later recover and make the gap too large.
I've even seen some forcibly hold down the throat A key pad cup which is even worse as that will compress the A key pad which will later recover and then prevent the G# pad from closing if the gap is made small. Where they got this idea from is a mystery to me and no-one should ever use this method - ever.
I test the adjustment by gently opening the thoat A key and feeling for the action (lost motion) between the throat A key and the adjusting screw, then adjust it to how much of a gap I feel is adequate depending on the types of pads used.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Paul Aviles
Date: 2015-06-21 06:35
Yes, exactly Chris, adjust according to what you have. I have the Valentino Masters on those keys and have been tempted to actually adjust the action like the 1and 1 "Bb" but that lasted all of five minutes. I just HAVE to leave some play!
...............Paul Aviles
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