 The Clarinet BBoard
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Author: TJTG
Date: 2014-03-15 00:36
So, when we seat a pad, we're trying to make sure it makes a good seal over the tone hole. Many people quickly test it by sucking and blowing on the joint while sealing all the holes and end of the joint. I'm curious, why do we test for suction at all(sucking on the instrument)? Shouldn't the test be on how much pressure is applied before a pad pops open (blow into the instrument)?
I just finished re-padding a clarinet and the top joint is not letting me blow air into it, but when I suck on the joint it allows for some leakage. Does it matter that one way seals and the other doesn't??? I'm letting the clarinet sit with all the pads closed to see what it will be like tomorrow, but I'd like to hear some opinions.
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Author: Paul Aviles
Date: 2014-03-15 03:41
First off, (you probably did this but I'm just making sure) you should let the pads develop a good crease overnight before taking the horn for a test drive (there are seating gizms available to facilitate this....reverse spring design).
Once the pads are "seated," a good positive pressure AND suction test are the best methods for checking the final work. Personally I find the suction test to be a better judge of the final product. It should hold a seal (like a coke bottle) for at least 5 seconds or ideally until you release an end or lift a finger. Positive pressure will help suss out a problem with the crows foot or whether the "Ab/Eb" pad has enough spring tension, but otherwise it's just not accurate enough.
Think about it, as you blow into the horn are you going to "feel" a very slow leak?
Once you determine there is is slow leak (like yours), careful use of a "feeler gauge" at each quadrant of each pad should reveal the culprit.
..............Paul Aviles
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Author: Caroline Smale
Date: 2014-03-15 03:47
The proper test for pad seating is to use a feeler guage made from say cigarette paper to check that it seats evenly at all points of the compass.
The blow or suck is a rather crude check but can give some additional confidence.
Small leaks are much more sensitive to a vacuum than pressure so thats why one uses suction - but it must be a VERY light suction since it's quite easy with high suction to pull the skin of a pad onto the tonehole rim and give a false indication of airtightness.
Similarly the finger pressures used should be no greater than for normal playing.
Leaving pads clamped closed overnight my give an indication of a seal in the morning but this is only short term as the felt under the skin will soon revert to it's original (faulty) condition some while after pressure has been removed.
A pad should seal correctly from the instant it has been properly installed and leveled.
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Author: cyclopathic
Date: 2014-03-15 05:45
+1
also leak light helps, but the paper feeler and very light touch is the best way to find small leaks.
It is amazing how much difference on how good your clarinet sounds small leak can make
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Author: TJTG
Date: 2014-03-15 13:15
Good points all around. With the Eb key. I notice on all clarinets it seems rather weak. When you blow air into the lower join the Eb key almost always the first to open up. I notice any adjustment to the spring does nearly nothing. This is normal yes? If the tension were too high it would make that key feel disproportionately more resistant than the others.
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Author: kdk
Date: 2014-03-15 18:21
Norman Smale wrote:
> The proper test for pad seating is to use a feeler guage made
> from say cigarette paper to check that it seats evenly at all
> points of the compass.
> The blow or suck is a rather crude check but can give some
> additional confidence.
This is certainly true, especially for checking a re-pad you've just done. A suction test gives you an overall assessment of the tightness of a joint. Testing with a feeler gives much more information about specific pads.
If you're trying to diagnose a problem in a clarinet with established pads rather than bench testing a new re-pad of a joint, feelers may miss a couple of sources of leakage. A porous pad or one with a small tear in the covering not visible without removing the key may seat well according to a feeler but still leak. Likewise a pad that seats on a tone hole rim that has a small irregularity. So if you're troubleshooting a clarinet because it doesn't feel right, you can initially test for cumulative leakage with a suction test to zero in on which section is leaking, and by pressing on specific pads while you test, maybe even find the specific problem pad. Once you replace a suspect pad with one of known quality and in good condition and inspect its tone hole, the feeler is used in leveling it.
Karl
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Author: Steven Ocone
Date: 2014-03-16 05:20
You will find get different information with different methods. Also, the force with which you suck or blow with makes quite a difference. Feeler gages are great for padding, but don't let you know if you have a leak. A leak can be the result of a crack in the wood, a ragged tone hole, a leaky pad skin, and they can occur at thumb tubes, register tubes and tone hole inserts. With a clarinet disassembled and the holes plugged up a vacuum should be strong and last a long time - until you get bored. It is good to get this base reading, so you can eliminate leaks from sources other than the pads. Then, the seal is tested after each pad.
My shop uses a magnehelic gage which puts pressure in the clarinet to determine how well it is sealing and to identify the source of leaks. This eliminates problems arising from sucking to hard and identifies leaks not found by sucking. Sucking pulls the pad surface down to the tone hole. It is rather expensive to buy for the home repair shop but worth it if you are serious.
Steve Ocone
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Author: Gordon (NZ)
Date: 2014-03-16 15:38
I don't use suction. I gently "squirt" a mouth full of air into the instrument at low pressure - not enough to lift a pad against its spring to the point of leaking.
My throat is blocked by the back of my tongue. So this is the opposite manoeuvre from sucking up a mouthful of drink through a straw.
The mouth is riddled with sensors that detect any loss of pressure. So this does the same thing as the fancy "magnehelic", but without the quantitative reading output.
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Author: eliotah
Date: 2014-03-16 19:34
look at this post that i put in clarinet pages
works perfect for testing and very cheap to make
http://clarinetpages.info/showthread.php?tid=441
Post Edited (2014-03-16 19:39)
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Author: Gordon (NZ)
Date: 2014-03-17 03:11
You mean http://www.amazon.com/gp/product/B0007VT...UTF8&psc=1 ?
For me the link does not work.
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Author: eliotah
Date: 2014-03-17 21:20
and it works amazing! i already overhaul a clarinet using it and it came out amazing.
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Author: clarnibass
Date: 2014-03-18 08:29
>> First off, (you probably did this but I'm just making sure) you should let the pads develop a good crease overnight before taking the horn for a test drive <<
I completely disagree with that. If I replace a pad and it requires waiting overnight until it is "ready" then it wasn't installed accurately enough in the first place.
Actually I consider it important to get the pad accurate and sealing before creating the "seat", for the reasons Norman mentioned.
I have a magnehelic machine too but don't consider it gets better results than using the method Gordon described. The critical point being "The mouth is riddled with sensors that detect any loss of pressure". This is different than simply sucking or blowing into the clarinet.
The main reasons I like the mag machine are that I don't need to put my mouth on many random instruments and that once I have it set up, it is faster and not tiring mouth/jaw muscles.
IMO the best method is... all of them. Sucking is a great way to get a very fast general idea. Squirting/blowing as Godron described is excellent.
A feeler is great to check one pad and almost always works but might miss a too porous membrane or leak more narrow than the (very narrow) filler.
A leak light is good too but difficult with more transparent pads and with clarinets where the side of the tone holes get in the way.
Post Edited (2014-03-19 01:26)
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Author: tictactux ★2017
Date: 2014-03-18 14:08
a great method to locate leaks, weak springs, investigate timing issues and required finger pressure is to attach a party balloon to the lower end of an individual joint or in lieu of the bell on the assembled instrument, and inflate it from the other end (with the keys closed, obviously). The large air reservoir gives you plenty of time to listen and locate tiny leaks (especially on the upper joint) and determine the correct ring height and all.
It certainly is no substitute for all other methods mentioned above, but a cheap additional method.
(For saxes, I use a latex glove over the bell.)
--
Ben
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Author: Gordon (NZ)
Date: 2014-03-18 18:21
Clarnibass, you might like to edit your post , replacing "filler" with "feeler". 
Re the party balloon: I reckon on many clarinets, that would be sufficient pressure to blow open spring-closed pads to the point of leaking, even when they did not normally leak.
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Author: tictactux ★2017
Date: 2014-03-18 17:12
I checked it - a fresh-out-of-the bag balloon might eventually pop the Eb/Ab pad open, but with subsequent fills, when the rubber is a bit worn in, everything's fine.
--
Ben
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Author: Gordon (NZ)
Date: 2014-03-19 10:11
So the reliability of the test is dependent on the lack of quality of the balloon material. I prefer to stick to my mouth-o-meter.
Post Edited (2014-03-19 10:12)
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Author: tictactux ★2017
Date: 2014-03-19 13:02
As I wrote, it's not meant to be a substitute.
When doing the mouth-o-meter thing (which I do as well) I can't determine the amount of required finger pressure as good as I can with the more relaxed test with the balloon.
--
Ben
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Author: Gordon (NZ)
Date: 2014-03-19 16:54
BTW I dampen my fingers first. Unless finger skin is quite tender, air can leak along fingerprint grooves over the ring key chimneys.
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