 The Clarinet BBoard
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Author: Micke Isotalo ★2017
Date: 2024-03-17 02:00
Attachment: Body ring screw.jpg (389k)
Several screws on a body ring on the lower joint of a bass are loose, with the wooden threads damaged (see the attached picture, with the ring and one of the screws on it).
Suggestions about how to fix this?
How about some super glue in each of the damaged holes, and after it has hardened, drilling a suitable hole for the screw (outer thread diameter is about 1.82mm, inner about 1.77mm)? A difficulty would be to get the hole centered (I only have handheld tools).
Another possibility without superglue would be to unscrew all the screws and then turn the ring, say 20-30 degrees, and make new holes for each screw (6 in total) - with even more drilling to get centered.
Other possible ideas?
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Author: RefacerMan
Date: 2024-03-17 02:18
One solution would be to use J. B. Weld, which is an epoxy. I used it on an old Buffet E-flat clarinet where the threads for one of the screws that held the top trill key guide was stripped out. I mixed up the J. B. Weld and put some in the hole and then put the screw into the J. B. Weld. I used a piece of tape on the outside to hold the screw in place until the next morning when everything had set and was hard. It worked great.
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Author: Chris P
Date: 2024-03-17 03:59
I put a drop of superglue in the screw hole and then refit the screw while the superglue is still liquid. Just be cautious with nickel silver wood screws as you have there as they're much softer than steel screws and are more liable to breaking if you overtorque them.
With nickel silver screws it's always best to cut the threads in the wood before fitting them instead of screwing them directly into an untapped pilot hole in the wood to be sure the heads won't shear off.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Micke Isotalo ★2017
Date: 2024-03-17 11:56
Thanks for the answers, and thank you Chris also for the "heads up" concerning nickel silver screws.
A problem here is also that there is quite a lot of stress on that ring and its screws, since they keep together a two-piece joint. Thus, every time the instrument is played resting on a floor, there are considerable bending forces involved (that's of course also why the screws have gotten loose in the first place, with tightening needed at least about once a year - but now some of the threads have eventually become stripped out).
Thus I'm thinking that a solution that merely keeps the screws in place (with glue), but without the possibility of tightening them afterwards, wouldn't stand the stresses involved.
Gluing the whole ring on to the body parts would probably be a solid solution, but then I suppose that ring wouldn't ever be removable again - but perhaps that wouldn't matter (I suppose the same would apply also to glued screws)?
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Author: Julian ibiza
Date: 2024-03-17 16:32
I would be inclined to set both the ring and the screws with epoxy and hopefully be done with matter. Things tend to get like that because they weren't really strong enough in the first place , so a lasting repair means leaving them even stronger than they were originally designed . There's no reason I can think of why one would ever want to remove the ring anyway, but the prospect of it coming lose periodically is obviously a pain.
Julian Griffiths
Tel. 34 696 798 853
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Author: clarnibass
Date: 2024-03-18 11:53
The second method wouldn't work if there are other parts attached to the ring, like posts, etc. which is common on many bass clarinets. I imagine it doesn't but just to keep in mind.
Super glue by itself wouldn't work well that way and would strip from very mild tightening. Super glue with wood dust combined would be better but still likely not anywhere near well enough.
>> I mixed up the J. B. Weld and put some in the hole and then put the screw into the J. B. Weld. I used a piece of tape on the outside to hold the screw in place until the next morning when everything had set and was hard. It worked great. <<
This can be a good method if you don't mind essentially gluing the screws to the clarinet body and ring. For that purpose almost any good quality epoxy is fine.
A similar alternative is to lightly grease the screw before. This has a good chance of creating the threads and allowing the screw to thread out. That's the advantage, but epoxy is not that great at supporting threads like this, even the better ones like JB Weld.
You can also try just Medium thread locker. It works in wood too. It's a question how much it would prevent the screws from threading out but maybe worth trying.
If the ring itself is loose without the screws then it's better to fit it. I've posted a few times why I prefer to use shellac for this and not using a shim, but there are many options.
>> Gluing the whole ring on to the body parts would probably be a solid solution, but then I suppose that ring wouldn't ever be removable again <<
If you use shellac then it's pretty easy to remove it. If you use epoxy it's also ok. It requires higher temp, but once the epoxy gets to that temp it loses its gluing. Some of that temp would touch the wood, at least for a few second, so depends if that is safe (not sure). But yes, it probably doesn't matter if it's never removed. With maybe a few very rare exceptions, the only reason to remove a reason is to tighten it if it's loose.
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Author: Chris P
Date: 2024-03-18 14:51
I've superglued them in on countless instruments with wood screws going into a blind hole to prevent the socket rings from turning and had no problem with that method. As I said, add a drop of superglue into the screw hole and fit the wood screw while the superglue is still liquid, then the superglue will set around the screw threads and bond it in place.
All these wood screws are doing in this instance is preventing the socket ring from shifting about as they have pillars soldered to them and aren't there to secure the socket ring to the socket, especially on wooden basses where you want to be able to adjust the tightness of the socket ring depending on the humidity levels.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
Post Edited (2024-03-18 17:05)
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Author: Micke Isotalo ★2017
Date: 2024-03-19 01:37
Attachment: Bass lower joint.jpg (414k)
This ring isn't a socket ring, but a ring keeping together a two-part lower joint (see the whole joint in the attached picture, with the ring approx. at 1/3 of the total length from the bottom). No posts or anything else are attached to the ring.
Glued screws would surely keep the ring from turning, but since no torque at all would be possible to apply to such screws, I suspect that the current rocking of the two body parts at that joint would continue.
I'm leaning towards gluing the ring itself to the wood underneath, and then merely for "cosmetic" reasons putting back the loose screws with some glue.
How about oiling the screw threads, instead of greasing them prior to the gluing - to be able to unscrew them, in case the gluing of the ring to the body would come loose one day, and thus had to be redone? I'm thinking that grease could be too thick (and messy), and hinder the screws to attach sufficiently to the glue. Maybe with key oil?
Post Edited (2024-03-19 14:07)
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Author: Chris P
Date: 2024-03-19 02:12
It IS a socket ring as that's exactly the purpose it's serving which is supporting the socket and reinforcing it, even though the two sections of the lower joint are both glued together. There's still a tenon and socket joint there which has been made semi permanent so it can be separated if it really needs to be.
It's always better to reinforce this type of joint on clarinets - whether it's a two-piece lower joint on Leblanc bass clarinets or basset horns as well as Buffet Prestige low C basses (which have a decorative turning to disguise the joint), or clarinets that had a socket graft done to the top end of the lower joint to be sure the new section doesn't split at the lower end, although that's best done with a carbon fibre band to make it far less conspicuous than a metal socket ring.
I don't know where this notion of oiling wood screws has come from, but it's a bad idea and shouldn't be entertained. If you want to remove a stubborn wood screw, then heating it up with a soldering iron with the tip made to the required size to fit in the slot will help do that.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Julian ibiza
Date: 2024-03-19 11:32
It's my bet that with all the screws removed there will be a little sideways wobble between the two sections. This can't be, because then the screws will be subjected to an unfair strain and their countersinks will act like a wedge, uprooting them out and tearing the wood or whatever you try to repair the holes with.
Ie. the lifting screws are a symptom of the real underlying problem.( hopefully not bad design).
Julian Griffiths
Tel. 34 696 798 853
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Author: clarnibass
Date: 2024-03-19 12:32
>> I don't know where this notion of oiling wood screws has come from, but it's a bad idea and shouldn't be entertained. <<
It's not oiling the screws in that sense. It's just a mold release, in case someone wants to mold the threads rather than gluing the screws in place. Grease just happens to work great for that purpose, usually. This depends on the material you use for the "casting" and how tight you tighten the screws... so whether it works or not is debatable, but worth mentioning the method and could be worth doing.
>> How about oiling the screw threads, instead of greasing them prior to the gluing - to be able to unscrew them, in case the gluing of the ring to the body would come loose one day, and thus had to be redone? I'm thinking that grease could be too thick (and messy), and hinder the screws to attach sufficiently to the glue. Maybe with key oil? <<
You could use oil, but make sure to basically wipe it "all" before. If it's a bit runny and sort of mixes with the epoxy it could ruin it that critical area of the threads. It's all very small so doesn't need much to happen. Grease isn't too thick or messy if you use a good type of grease. You need a soft and relatively non-sticky type of grease (some grease is sticky and gummy, wouldn't be good at all). Smear a little on and remove most of it, leaving just a very thin layer. I prefer grease over oil for that reason, but if you don't have a grease that would allow that then yeah, it wouldn't work well.
You also need a type of epoxy that would work as a threaded hole... most are not. JB Weld is decent for this and even that is questionable. If you don't mind gluing the screws in place then I would just do that. I just threw that "thread casting" out there as an option, not necessarily what I'd recommend.
If the root cause of the issue is that the ring is loose then most important to tighten it, just glue it in place, then do whatever you prefer with the screws.
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Author: Micke Isotalo ★2017
Date: 2024-03-20 01:33
Attachment: 1 Body joint.jpg (489k)
Attachment: 2 Screw hole splinter.jpg (402k)
Attachment: 3 Plumbers tape.jpg (399k)
Attachment: 4 All covered up.jpg (497k)
Chris was right about the ring being a socket ring (of course  ) - see the first attached picture.
The tenon cork there felt bone dry, and appeared shrunken - with a lot of wobble, at any position while sliding the tenon off the socket (this now 40 year old instrument was in for a general overhaul about 10 years ago, but obviously this joint was overlooked). Can't imagine this joint being airtight either.
Second picture shows exactly what Julian said, about the wobble acting like a wedge through the ring on the screws - eventually uprooting them (after a lot of fiddling under a magnifying glass I managed gluing that splinter back into its place).
Probably my new cork wasn't thick enough (though about 0.95mm thick, compared to the original 0.8) - perhaps since I stretched it while putting it on the tenon - as the joint was still wobbly. In a whim I then went against all common sense, resorting to .... plumbers tape (third picture)! Nevertheless, four layers eliminated all wobble, so no glue between the ring and the wood underneath. Just a dab of superglue in one of the screw holes, enough to keep its screw in place - but still removable if needed, I believe.
Last picture shows everything "covered up".
Don't think my original plan about gluing the ring to the wood had been a good solution, since there were just too much play. Time will tell for how long this plumbers solution will last, but if not for too long, then a proper tech could still easily take everything apart again - for a proper solution.
Post Edited (2024-03-20 01:40)
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Author: Chris P
Date: 2024-03-20 02:56
The tenon cork was probably reasonably fat and left 'American' style with square shoulders when the sections were first fitted together, then the cork perished over time due to being permanently compressed. The same happens under the top joint socket section as there's a tenon cork under that as well.
One thing you can do is replace the tenon cork with a thick one (1.6mm thick cork) and also seal the end grain of the tenon and the socket with a generous amount of beeswax so it oozes into the bore when fully assembled (and is then scraped off afterwards). You can also carefully and gently heat the tenon and socket with a hairdryer to help melt the wax to create a better seal when the sections are assembled.
With the top joint socket being metal, that's much easier to heat up due to it being a far better conductor of heat compared to wood.
Another thing you could do is fit silicone rubber O rings on the tenon either side of the cork (Yamaha 221 bass style) as they will last far better than natural cork when left assembled for decades. I once tried using tech cork for this joint, but it compressed and didn't recover while left assembled and the joint began to wobble.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Chris P
Date: 2024-03-20 03:01
What would be better in this application of a socket ring is instead of having screw holes going through it and in close proximity, metal straps could be hard soldered onto the socket ring that in turn will be screwed into the wood - maybe three or four on each side and staggered instead of all in line with each other. And use two wood screws per strap and that will keep things held nice and tight.
Take a leaf out of oboe or cor anglais socket rings which have these exact straps which not only help lock the socket ring in place, but also prevent it from turning.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: clarnibass
Date: 2024-03-20 12:11
>> Time will tell for how long this plumbers solution will last <<
The thing with Teflon tape (and coincidentally I just learned the English translation of the definition recently) is that it's very susceptible to creep. Google it if you like. Basically it will slowly and gradually lose its usefulness for this purpose over time. Long before I knew that, I tested it in various woodwind mechanisms for removing play and found that it is exactly what happens.
>> Don't think my original plan about gluing the ring to the wood had been a good solution, since there were just too much play. <<
Most epoxies would work very well for this, filling the gap, and not only gluing them but giving support. Important to not go with one of the epoxy types which stay more flexible, which wouldn't (not specifically a flexible epoxy, some regular ones are just a bit softer when dry, not to the point where you can easily feel it, and would just give less support in this case).
>> Just a dab of superglue in one of the screw holes, enough to keep its screw in place - but still removable if needed <<
If the Teflon tape covers the screws, as it is now covering the holes, then the glue wouldn't really glue to them (Teflon is mostly non-stick). You could puncture holes and do it, or just see if the squished Teflon itself is holding them better (but then that creep again...).
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Author: Julian ibiza
Date: 2024-03-20 17:47
I get the feeling that there is maybe some confusion about how to apply Teflon tape. It should be wrapped very tightly..... just below breaking point. The stretched turns becoming only microns thick and clinging to one another.
Not sure what you mean by " susceptible to creep" Clarnibass. Teflon tape is "self distributing" however, which means it will displace from where it's under higher compression to areas of lesser compression, which I guess is what makes it so good for certain applications.
It's impervious to water and oil, and does not otherwise degrade over time in my experience. Also its lubricant quality makes it particularly good for the assembly and disassembly of surfaces under pressure.
That at any rate has been my experience of the stuff.
Julian Griffiths
Tel. 34 696 798 853
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