 The Clarinet BBoard
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Author: johnhcl
Date: 2015-04-11 23:38
Hi, can someone explain to me what a facing length is and how it is measured?
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Author: kdk
Date: 2015-04-12 02:02
The facing length normally means the distance down the rails of the mouthpiece from the tip to the point where the reed (or any flat surface) resting on the table of the mouthpiece meets the rails - the point where the reed and mouthpiece separate. The significance is that it gives the length of reed that is free to vibrate.
It's measured most accurately by holding a glass plate marked with a measuring scale against the mouthpiece table and recording the length (on the glass's scale) a thin flat object slid (carefully and unaggressively) down between the mouthpiece and the glass stops.
The standard equipment is a glass gauge marked off in 2 mm units. The entire curve is measured using specific standard feeler gauges (like the ones used back in history to measure spark plug gaps). The feeler normally used to approximate the meeting place of the reed and the mouthpiece rails is .0015" That feeler stops with most French-style mouthpieces anywhere between 15 mm (30 on a standard gauge) and 18mm (36), with some facings nudging past that.
Karl
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Author: Tony F
Date: 2015-04-12 14:38
I think you meant half millimetre units, not 2 millimetre units.
Tony F.
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Author: kdk
Date: 2015-04-12 18:49
Yes. Thanks for the correction. The examples I gave were right. 34 on the gauge equals 17 mm. The markings are at 1 mm intervals, but each mark represents 2 units of curve length, the even numbers. You read odd numbers between the marks.
Karl
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Author: WhitePlainsDave
Date: 2015-04-13 03:07
http://test.woodwind.org/clarinet/BBoard/read.html?f=1&i=214286&t=214242
Here's one of many useful threads that somewhat translates facing length into the categories of short, medium, and long used within the industry.
There are no hard standards to my knowledge on facing length, and people may differ on whether the ranges cited here are appropriate.
Posters above have done well to explain what facing length IS--which may be all that you're looking, and seemed to ask for, but there's also its practical affect on play, and the "well, how do such measurement's translate into their affect on play" factor.
Take two mouthpieces with equal tip openings, all else equal, (which by the way is almost never the case, as all else is rarely if ever equal in the world of mouthpieces,) the mouthpiece with the longer more gradual facing *may* require harder reeds.
It really depends upon really the facing curve, which as discussed above is measured with feeler gauges, and is the complex curve unique to that facing. The further back from the tip of the mouthpiece the curve causes the reed to seperate from these rails, all else equal, the weaker the reed you can play on. But it also depends, once the facing seperates from the reed, on the extent of its curvature, and where along the facing it does more or less of this curvature. Early curvature will require weaker reeds than late curvature.
So, if all else is not equal, what else is there? There's rail width, and the curvature with which those rails curve to become smaller towards the tip (in other words the sliming of the rails you see looking down on the mouthpiece window, not the aforementioned curve you see when you look at a side view of a mouthpiece), there's the distance between the rails and their symmetry with one another, the size of the window, the materials the mouthpiece is made of, the nature of its internal structure and thickness in various parts, just to name several attributes.
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Author: kdk
Date: 2015-04-13 05:14
WhitePlainsDave wrote:
> The further back from the
> tip of the mouthpiece the curve causes the reed to seperate
> from these rails, all else equal, the weaker the reed you can
> play on.
Other way around - the longer the curve (the farther back from the tip of the mouthpiece the reed and mouthpiece separate) the stronger a reed can be used. At least in theory. Of course, all the other variables you mentioned tend to confound this relationship to an extent.
To the OP, if you're looking for discussion of the effects of different facing shapes and measurements and the advantages of long vs. short curves (and open vs. close tip openings), there is already a major mountain of the stuff available here via the search utility. You can certainly ask more questions and get fresh discussion in this thread - it's one clarinet issue that seems never to cause discussion fatigue, but I doubt if there's anything much new to say that hasn't already appeared here in the past.
If you want to see a gauge you might look at http://musicmedic.com/products/repair-tools/mouthpiece-facing.html.
What piqued your curiosity about curve measurement?
Karl
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Author: WhitePlainsDave
Date: 2015-04-13 07:10
I see your point Karl.
Mine was that the sooner this curve begins, all else equal, the larger we can normally expect the tip opening and the business end of the reed to be. And the larger the tip opening, all else equal, the weaker the reed often needed.
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