 The Clarinet BBoard
|
Author: Ken Shaw ★2017
Date: 2012-02-10 15:03
On the Musical Instrument Tech board, there's been a good discussion of Bundy keywork, noting that while a wood body is relatively stable, a plastic body expands and contracts with temperature change. Therefore the keys, particularly the long ones, must be made shorter than the distance between the posts. Bundy keywork in particular is very difficult to swedge.
One solution is to twist a length of Teflon plumber's tape into a tight string. With a sharp blade, cut off about 1 mm. and push it into the screw hole. Reassemble and as you tighten the point screw it will drive into the pellet of Teflon. This won't close up the gap, but it will take up the slop in the pivot.
This works only for pivot screws. For rod keys, thin Teflon washers, available from optometry equipment suppliers, can be inserted between the post and the key body.
The problem is even worse on plastic basses and contras, leading to imprecise action, key clanking and even leaks.
A plastic instrument fixed up this way won't play outside, or maybe even in a cold concert hall, so the changes must be made with caution, but how many contras are there in a marching band?
Has any repair tech tried this? What do you think?
Ken Shaw
|
|
Reply To Message
|
|
Author: Chris P
Date: 2012-02-10 15:17
While plastic basses and contras won't be used for marching, they will still be used in concert bands playing in cold churches or outdoor concerts in adverse weather conditions as is usually the case, so a certain amount of end play is critical for these conditions.
During warmer months, plastic or teflon shims or spacers can be fitted to take up the slop and then removed again for playing in Winter when everything tightens up.
Bundys are good in they have parallel pivot screws so the keys should only move laterally between pillars (they act like pistons in the ends of the keys), but point screws with tapered or bullet tips will have play in all directions, so the action won't be as precise. But parallel pivot screws are only good provided they're a good fit in the ends of long keys.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
|
|
Reply To Message
|
|
Author: alto gether
Date: 2012-02-10 18:39
My tech said that, since the adjusting screws have to have slop to allow for body contraction, you put a dab of clear nail polish on them so they don't vibrate loose. I lost two screws from my Bundy contra alto in the first week, after winter shipping.
|
|
Reply To Message
|
|
Author: tictactux ★2017
Date: 2012-02-10 18:43
The proper solution would be to use minibal joints. Whether or not this is also an economical solution is a different question.
Another idea would be to modify some springs so that they not only re-open or re-close the keys but also push/pull against a default post, so that the slop is only on one side of the rod.
--
Ben
Post Edited (2012-02-10 18:46)
|
|
Reply To Message
|
|
Author: Paul Aviles
Date: 2012-02-10 23:01
The REAL solution to the "slop" would be Gerold's 'One side distance control.' In a nut shell the rod really only holds on the thread side, the other side is free to expand or contract as much as you want !!!
.................Paul Aviles
|
|
Reply To Message
|
|
Author: clarnibass
Date: 2012-02-11 05:57
Re the teflon in the pivot screw hole idea, I think I've posted about this before, I think it's not a good method. I've tried more than a few times to test. You put teflon until it's just right, then play the key a little bit and it's loose again. You put teflon untl it's just the tiniest bit too much, so there's some resistance actually, play the key a bit and it's already less resistance. Play it some more and it's loose! So even putting too much teflon will make it loose after a relatively short time IME.
I sometimes use teflon washers for loose hinges but only in emergencies or when budget is extremely small. There are a lot of disadvantages to this method. they are not super accurate, easy to lose when disassembling, etc. I don't use them unless it's absolutely necessary in a certain situation. Eventhough the pivot are pilot type, they are sometimes still loose around them (like a hinge tube).
|
|
Reply To Message
|
|
Author: Bob Phillips
Date: 2012-02-13 16:04
A local bassoonist lubes with 3:1 oil and STP to produce a very viscous (near grease) lubricant. It does help a bit. I think that the 3:1 oil is volatile and leaves behind the STP after helping the mixture wick into the space between key and pivot.
Bob Phillips
|
|
Reply To Message
|
|
Author: Ken Shaw ★2017
Date: 2012-02-13 19:12
François Kloc of Buffet appears, or at least used to appear, at KlarinetFest to do small repairs on Buffet clarinets. He used axle grease for lubricating keywork. He said that in small amounts the relative thickness doesn't interfere with key action, and it lasts longer.
Ken Shaw
|
|
Reply To Message
|
|
Author: Caroline Smale
Date: 2012-02-13 21:37
Grease is a standard substance for lubricating point screws as the contact area is so small that drag is virtually non-existant and the grease does not readily migrate away from the bearing as would oil in this area.
Oil should always be used on rod bearings, the ideal viscosity depending on the structure of the mechanism e.g. very light on flute pinned sections vs heavier on saxophone and bassoon with clarinet in between.
|
|
Reply To Message
|
|
Author: David Spiegelthal ★2017
Date: 2012-02-14 14:37
No solution is perfect or lasts forever. My personal preference is to cut small "washers" out of Teflon sheet (I have various thicknesses), to go between one or both of the posts and the key rod, with the screw poking through the middle of the sheet. If it's a pointed pivot screw I usually use a solid disk of Teflon and let the screw itself make the hole through it, but it it's a cylindrical pivot screw or a rod screw I'll pre-cut the hole through the Teflon shim using a sharp knife.
|
|
Reply To Message
|
|
The Clarinet Pages
|
 |
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
