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Author: LJBraaten
Date: 2024-12-03 09:17
My recently purchased used (Giardinelli) bass needs new tenon cork on the lower joint. It looks like I’ll need around 4.5” to be safe. My Bb soprano tenon cork sheets look a little short, so I will need to use something else. Web searches are not coming up with anything for bass, so I suppose I’ll need to just use a large sheet. I have a couple of sheets of all purpose cork, but they look too thick. What is the general thickness that I should be looking for?
Laurie (he/him)
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Author: Chris P
Date: 2024-12-03 12:16
There aren't any standard dimensions for tenon cork strips - you have to cut the strip according to the width of the slot from sheet cork. Typically most clarinets use 1.6mm thick sheet cork and others may require 2mm thick depending on how deep the slot is.
In some cases, you can always line the tenon slot with a layer of thin cork (around 0.5mm) or synthetic cork and then glue the regular thickness cork strip over the top of that if the slot is on the deep side. Make sure the overlapping joints on both cork strips are on the opposite side of the tenon from each other instead of both being on the same side.
A typical piece of sheet cork of 150mm long by 100mm wide will be sufficient to cut a strip the required length to go around a bass clarinet tenon. Bear in mind that thicker sheet cork will be more prone to breaking when bent around the tenon, so go carefully if you are using 2mm thick cork.
DO NOT BUTT THE FREE ENDS TOGETHER! Always do an overlapping joint (bevel the end of the strip that's to be glued into the slot) as that won't leak.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2024-12-03 12:23)
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Author: Chris P
Date: 2024-12-03 13:31
As for the shape of the tenon corks, barrel shaped is best for well fitting tenons and sockets if the cork strip isn't too wide (up to around 15mm wide). Anything wider than 15mm can be left flat in the middle with the sides neatly rounded off and made flush with the tenon rings. That's much easier to achieve by spinning the joints in a lathe while sanding the tenons to get a nice uniform shape/profile.
If you do prefer the American look of having flat-sided tenon corks (quite honestly why it's even a thing is anyone's guess), then do at least bevel or round the leading edges instead of leaving them square so the tenon corks won't get torn off during assembly.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LJBraaten
Date: 2024-12-03 20:36
hanks for the response! I have a full sheet of 1.6 mm which is long enough to cut several strips. I would also bevel the edge that is glued to the tenon at the overlap, like some cork is sold for the Bb soprano tenons. (Unfortunately my .3, .4 and .5 tech cork sheets are all too short for the top layer option.) Yes, sanding to round off the edges is important, and is usually the most difficult and labor intensive part of the job! (I do both edges.)
Since I won’t know what thickness I need I until I strip the cork off I will order a thicker sheet beforehand in case the 1.6 is too thin. Your information is very helpful for giving me a general estimate on what size to order since I’ve never replaced bass tenons. I can always sand it down (another labor intensive task) if it’s too thick.
BTW: my current stop gap is masking tape wrapped halfway around the tenon. (A full wrap was too thick.) The bell is now secure and doesn’t move every time it touches my ankle, and I think it also has eliminated an annoying vibration rattle.
Laurie (he/him)
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Author: Chris P
Date: 2024-12-03 23:32
You don' need a continuous strip of tech cork - you can always make a longer strip by cutting a bevel on one end and gluing another piece onto that, then once glued into the slot, it can be trimmed or filed smooth and then the tenon cork can be glued onto that (with the bevelled end stuck in between the joints on the tech cork).
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LJBraaten
Date: 2024-12-04 08:39
Would the old tenon need special cleaning? I’m wondering how well the glue would stick to cork that has cork grease on it. ( I use contact cement.)
Laurie (he/him)
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Author: Chris P
Date: 2024-12-04 11:50
Yeah - thoroughly clean all traces of old adhesive and degrease the tenon slot to be sure the adhesive will bond to it (using contact adhesive). Only use isopropyl on plastic clarinets and use either isopropyl or acetone on wooden clarinets as solvents won't harm wood.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: clarnibass
Date: 2024-12-06 10:37
>> my .3, .4 and .5 tech cork sheets are all too short for the top layer option <<
Because you used them? The smaller/shorter sheets usually come in 15cm lengths (6").
>> Yes, sanding to round off the edges is important, and is usually the most difficult and labor intensive part of the job! <<
I prefer to curve the corners instead of an exact barrel shape, and do most of the sanding before gluing the corks. It's pretty fast and not labor intensive. I have a lathe so it's not lack of tools, I just like the result better that way.
>> Would the old tenon need special cleaning? I’m wondering how well the glue would stick to cork that has cork grease on it. ( I use contact cement.) <<
I wouldn't call it special but it's important to clean them or it would glue poorly or not at all.
Not sure what you mean by "stick to cork that has cork grease on it"? Do you mean tenons that have some grease on them? If you really mean the cork itself, I wouldn't bother even trying to glue anything to greased cork.
>> my current stop gap is masking tape wrapped halfway around the tenon. (A full wrap was too thick.) <<
Try teflon tape. It is much thinner than most tapes and it's the best DIY stop gap for this.
As far as thickness in general, I prefer not to use anything thicker than 1.6mm, and often 1.2mm is good. I stock 1.4mm too and use the one that fits best.
This has been accused of being overkill... but I measure the diameter of the socket, subtract the diameter of the tenon and choose based on that.
I just don't really like the feel of cork thicker than 1.6mm. In the occasional case that this is not thick enough, I either use a layer of thin rubber cork (aka tech cork) under the cork and then 1.2mm cork (which I prefer over thinner rubber cork and 1.6mm cork, which also works fine).
Post Edited (2024-12-07 09:59)
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Author: Julian ibiza
Date: 2024-12-06 18:23
If you think " barrel shape " while sanding the cork, I would just warn that it's important to leave enough solid contact between the finer ends of the "barrel" to prevent the joint rocking laterally. One thing is that the joint is hermetic and enters with the right amount of pressure, and another thing is that it holds the sections in alignment. These are the two jobs the tenon must perform.
Julian Griffiths
Tel. 34 696 798 853
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Author: Chris P
Date: 2024-12-06 21:03
Ideally tenons should be as wobble free a fit in their respective sockets as possible even without the tenon cork fitted - the tenon cork providing the airtight seal as well as exerting outward pressure within the socket to keep the joints held securely.
You can't guarantee a wobble free fit if the tenon is undersize and a thicker tenon cork is fitted, especially the middle joint on all instruments and the bells on bass clarinets if you're using a spike with the fitting soldered to the bell socket. Also bass mouthpieces can wobble like anything if the tenon is significantly undersize compared to the socket and you're best sleeving the tenon to add stability than bunging on loads of cork.
I don't care for American style flat sided tenon corks as they just look amateurish - especially if the edges are left square.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: LJBraaten
Date: 2024-12-07 01:05
Thanks for the responses! I realized I asked the question incorrectly. By cleaning the tenon I meant cleaning off the existing cork before applying a thin layer of tech cork or teflon (I have both). The tech cork has had pieces cut off. Both the tech cork and Teflon are a little over 4 inches long. They would almost fit, except a layer of contact cement in each side is going to increase the circumference.
I just sand the edges, no barrel shape. The labor intensive part is sanding down the cork when it is too thick, especially my last replacement when I sanded off too much and had to start over, oy! 😣
Laurie (he/him)
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