 The Clarinet BBoard
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Author: ffrr
Date: 2005-04-02 22:14
OK - armed with warnings and advice from here, I tackled my clarinet pivot screws. My reasoning for attempting it are ...
1. I agree that a player should learn as much about their instrument as possible (including maintenance)
2. I am not 'hamfisted' and have worked on lots of other delicate mechanisms before
3. It is NOT an expensive instrument (Vito) so scope for damage is limited :-)
So, I went over each pivot on the clarinet. I found...
- one screw about to fall out - needed quite a few turns to tighten
- a few screws that caused the mechanism to get stiffer as I advanced them, so I backed them off a quarter turn
- All the side screws for the pivots for the levers that run up and down the instrument seem to have had loctite (tm) or something applied.
The one screw that was about to fall out, when tightened fully, did not tighten the associated pivot at all. When screwed hard up, the pivot was still very free - not sloppy, so it does not need further attention yet.
I was wondering what the mechanism is that tightens a pivot normally. I haven't removed this one yet, to find out how it works - thought I'd ask here first. Is there a taper that the screw is pulling the mechanism against - thus providing some measure of adjustment, and when this isn't working (as in this case), what is the usual method of fixing it?
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Author: Gordon (NZ)
Date: 2005-04-02 22:49
There are quite a variety of pivot systems.
The pivot 'RODS' (sometimes called 'steels') that you could not undo (e.g. for the side keys and low 'levers') are probably just well tightened (as they should be), such that they need a screw driver with a more substantial handle, &/or more finger strength to undo.
Technicians use 'grunty' screw drivers such as ...
http://www.krausmusic.com/handtool/screwdri.htm
The other possibility is that through lack of lubrication they have rusted either into the respective pivot tubes or posts. They could also be seized because of an unsuitable lubricant that has polymerised, resembling set varnish.
BTW pivot rods are sometimes called 'hinge rods'.
Pivot point screws (as opposed to rods) - on a Vito - are tapered at the end. You screw this tapered part into a hole drilled in the end of the rod part of the key. This hole may be either cylindrical or shaped roughly to the taper of the screw.. I've forgotten which is the case for Vito. So as you tighten the screw it securely positions the key both laterally and longitudinally. If you turn the screw in too far it forces the key away from the post, possibly damaging the mounting of the post.
"...When screwed hard up, the pivot was still very free - not sloppy, so it does not need further attention yet."
My guess - I've forgotten the exact Vito details - is that this particular pivot is probably the left first finger key - the F# key. This one consists of a combination of a pivot ROD for the F# key, and a POINT pivot incorporated at the end, for the D/A key. At the end of the rod part there is a shoulder, which is screwed tight against the associated post.
This system is common, indeed the norm, because it means that the screw can be well tightened and thus not work its way out. A locking fluid such as Loctite can be used on other point screws (and usually is for the headless type, which are used to make adjustment easier as on Vito) but for this particular key there is too much risk of it getting between the F# key's pivot tube and rod, and jamming the key.
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Author: jbutler ★2017
Date: 2005-04-02 23:44
Gordon, as always gives great advice. Vito pivot screws are "headless" and have a "nylock" insert to prevent them from backing out. A low strength thread locker such as Gordon suggests (Loctite #222) should keep them from backing out.
jbutler
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Author: ffrr
Date: 2005-04-03 00:41
["...When screwed hard up, the pivot was still very free - not sloppy, so it does not need further attention yet."
My guess - I've forgotten the exact Vito details - is that this particular pivot is probably the left first finger key - the F# key. This one consists of a combination of a pivot ROD for the F# key, and a POINT pivot incorporated at the end, for the D/A key. At the end of the rod part there is a shoulder, which is screwed tight against the associated post. ]
Close, it's the F key (I should have mentioned this in my post, sorry) It shares a common post in the middle (of 3 posts), with the G# key. It is the lower section with the screw coming up from the bell end of the clarinet.
Thanks again for the advice, I'm glad I was able to prevent the loss of this screw (and maybe others in future).
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Author: Gordon (NZ)
Date: 2005-04-03 09:42
Not close really. That pivot is always a simple pivot ROD, with the threaded part in the post ABOVE the G#/D# key. The G#/ D# key would actually fall off long before that long rod actually came right out of the F/C key.
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