 The Clarinet BBoard
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Author: jim lande
Date: 2013-06-21 05:43
I'm working on a Wm Frank Co metal clarinet. (The William Frank Company operated in Chicago from 1910 at least through 1950.) The pivot screws thread into the long keys and rotate when the key is pressed. I have never seen this before. I have seen some pivot screws that end in rods instead of points, but the threading screws into the post.
Has anyone seen this on another make of clarinet?
Seems like there would be more friction with this arrangement and if the key is loose between the posts, the pivot screw won't keep it centered. However, I have seen pointed pivot screws that pinch keys if they are screwed in all the way. Won't be a problem on this clarinet. Any other thoughts?
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Author: Gordon (NZ)
Date: 2013-06-21 11:25
It sounds as if the inside of the post becomes a bearing surface for a moving part. Warn holes in posts are far more difficult and expensive to deal with than worn holes in keys.
(We get this situation when a pivot rods is frozen inside a key barrel, and rotates within the posts.)
Post Edited (2013-06-21 11:26)
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Author: Chris P
Date: 2013-06-21 12:38
Another type of screw B&H used on some of their old Regent and Edgware flutes (the ones with expanded sockets) for a limited time were rod screws but with the thread on the slotted end instead of at the opposite end.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Paul Aviles
Date: 2013-06-21 17:22
I just ran into a representative with Lohff & Pfeiffer who do really high end overhauls on clarinets. They use this very arrangement for their top of the line overhauls. One end of the key is a pivot that is actually fashioned into a short rod; the other side (as described above) is a screw that fastens into the key itself. The difference is that Lohff & Pfeiffer add a ball bearing mechanism to the inside of the post !!!! I guess this is where the expense comes in.
...............Paul Aviles
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Author: Gordon (NZ)
Date: 2013-06-22 12:02
Some top-end flutes also have ball bearings.
I don't think that actually adds any accuracy, just wear resistance.
After all, there is the fit of the entire bearing with the pin and the post, and the fir of the balls between the races, all adding slight play.
And for any pivot with a cylindrical pin, there has to be be play if the key has to be put into its position from an angle, especially if the pin is long. Otherwise the pin would have to be bent to get the key between the posts.
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Author: Paul Aviles
Date: 2013-06-23 00:22
To defend to Lohff and Pfeiffer, the cylindrical pin IS a screw in , pivot like device perhaps just a bit longer than a normal pivot. So you screw it into place; no angling of key into place is necessary.
The Gerold Clarinet has an even simpler approach where the "head" of the axle is over-sized. It inserts THROUGH the near post and becomes what the key-axle actually abuts (this arrangement is quickly and easily adjustable for compensation of wood shrink and expansion). This over-sized "head" also has gaskets around it to prevent it from backing out.
http://www.gerold-klarinetten.at/en/amadeus-de-luxe.html
hover over "one-side distance control"
...................Paul Aviles
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Author: clarnibass
Date: 2013-06-23 06:10
>> The Gerold Clarinet has an even simpler approach where the "head" of the axle is over-sized. <<
If I understand it correctly from that tiny photo, it seems to mean the rod screw has to be kept loose and not tightened all the way, relying on friction of the threads to stop it from opening.
>> This over-sized "head" also has gaskets around it to prevent it from backing out. <<
This seems to prevent that problem, but I don't see "gaskets" in the photo (not completely sure what you mean by that) or anything else "around" the head for that matter. Do you have a better photo or a more specific explanation of how this works?
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Author: Paul Aviles
Date: 2013-06-23 13:55
Attachment: one side distance control.jpg (12k)
Clarnibass,
I kept a copy of the image from an earlier version of Gerold's website. Hopefully this will help. It appears to be a double gasket design.
................Paul Aviles
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Author: Gordon (NZ)
Date: 2013-06-23 14:44
It would be particularly important that the threads were a really good fit to eliminate radial play.
Slight play in threads doesn't matter a lot in the conventional system, because they are screwed up tight and secure.
There seems to be two O-rings. Why 2?
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Author: Chris P
Date: 2013-06-23 15:08
If double O-rings were good enough for the space shuttle, then why not?
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: mk
Date: 2013-06-24 01:05
I like the ball bearing concept from the standpoint of wear, but wood constantly expands and contracts consequently adjusting end play would be an issue. Fflutes are more stable in this respect so I can see it as more practical. Additionally, the price points of flutes are much higher. I can imagine shims working if they came in a variety of thicknesses so they could be added or removed to correct this endplay. I really am quite sure micro ball bearings could be manufactured without difficulty but I doubt there is any money to be made from the added cost of manufacturing.
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Author: clarnibass
Date: 2013-06-24 06:17
I live in a city where it gets close to 40C in the summer and sometimes snowing in the winter. Sometimes during the year the weather varies a lot in the same day e.g. almost have to be naked in the morning-noon to needing a coat in the evening-night and sleeping with a thick duvet. In addition I often go to another city where it's much more humid (my city is very dry). I play soprano and bass clarinets regularly and see many instruments of many other players.
That said, how often keys getting stuck or loose is a problem? I'd say, very rarely, almost never really, and even less when considering only situations that affect playability.
So, this extra mechanism is IMO unecessary except in possibly even more extreme weather changes than what I have, and even then I'm skeptical. That's even before considering all the other issues that would come with that mechanism.
BTW, a great use of ball bearing, with very good advantages, is used on the Eppelsheim instruments. They are used in a different way that helps with their design, very different to using them on regular soprano and even bass clarinets.
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Author: Paul Aviles
Date: 2013-06-24 10:14
I am more inclined to live without the Lohff and Pfeiffer "extreme makeover" just based on the old law-of-diminishing-returns, however I feel (since I kinda raised that aspect) a responsibility to correct some misconceptions of it.
The ball bearing side can be adjusted for ANY tightness or looseness since that "pivot" screws directly into the axis of the key itself (when the key moves, the head of the screw moves). So wood expansion and contraction is one of the main reasons FOR this configuration.
The ball bearings give it an incredible gliding feel (is this necessary? you must decide), as well as ability to last a long time.
Finally there is a very silent, foam pad (impervious to oils so I am told) that renders the sound of keys COMPLETELY without noise.
Even a visit to their website does not do it justice. You'd have to play with a sample to understand what the overhaul does........I'm sure they'll be in Italy next month !!!
...................Paul Aviles
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Author: Gordon (NZ)
Date: 2013-06-28 16:36
Are you referring to the pivot for which you provided a link?
You seem to say it screws into the key, but that photo shows a thread beyond the key, clearly intended to screw into a post.
(With the key rotating around the shaft, and the head part of the shaft adjustable to the very end of the pivot tube to remove any axial play. The screw would not be screed tight, but rather, adjusted to remove the axial play, with the O-ring looking thing holding it reasonably secure against turning after that adjustment.)
I don't understand you. What have I missed?
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Author: Paul Aviles
Date: 2013-06-28 18:45
There are two distinctly different mechanisms to which I refer above (sorry for the confusion).
The L&P version is very involved mechanically. One side is features a screw that goes through the post and directly into the key axle. As you tighten it, the key axle becomes more firmly brought up against a ball bearing on the inside portion of the post (you REALLY have to see an example to get it!). The other side of the key is a short rod (rather than a pointy pivot) that protrudes beyond the post and into that side of the key axle about a quarter of an inch.
The image is from a Gerold Angerer clarinet (he only makes German system alas). In this version of the same idea, the "head" of the rod becomes what secures the key axle in place, AND what holds up the key, AND what prevents the rod from unscrewing from the near post (as you stated). I only put that out there becomes it seems to address the L&P fix without too much mechanical complexity.
.................Paul Aviles
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Author: Gordon (NZ)
Date: 2013-06-29 11:45
For both systems, it seems that the gain of any significance, for all that complexity, is to avoid the need to ever swedge a key's pivot tube in order to better fit the space between the posts.
And over a (say) 70 year life of a clarinet, I don't see this as a big issue.
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