 The Clarinet BBoard
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Author: DMcCool
Date: 2021-01-11 13:03
Hi all,
I'm returning to the clarinet after a 20 year break. Money's tight, so we waited around until a used E11 (~2008) in good shape popped up used for €180. It plays quite well but is still using the original pads. Additionally, a tenon cork had rotted through. I've spent the weeks since Christmas reading all I could on how to go about these repairs at home and decided to get myself a beater clarinet to practice on before I attempted the cork repair on my E11.
I dropped €20 on a 1990 Vito 7212 and went about disassembling it carefully. The last bit was a stubborn stuck screw pivot rod for the thumb ring. I followed some advice online and "gently" heated the post after applying some key oil, which worked to offer enough space to unscrew the pivot rod, but when I had finished the process, I noticed I had created a hairline crack that extends about halfway around the body. And according to my highly-advanced suck-on-it test, it apparently goes through to the bore. Dumb me!
Which leads me to my question: does anyone have advice on repairing a crack in an ABS clarinet? I've found precious little online about a clarinet-specific process and have cobbled together steps from people discussing other plastic repair. I don't need it to be aesthetically pleasing -- I just need an instrument that is intact enough to judge whether my repadding and recorking efforts have been sufficient.
My plan now is to
1) Sand over the crack
2) Clean the crack through with isopropyl alcohol
3a) Dissolve a black lego block into some methylethylketon, keeping it very viscous so that it can enter the crack
3b) Maybe only use the MEK since it's a hairline crack? I'm still not sure.
4) Paint over the crack with the substance from step 3
5) Wait
6) Sand it and test it
I had difficulties sourcing ABS cement cheaply in my country, which is what led me to the MEK solution.
I've also seen people who advocated heat sealing, but I'm a little wary since my only tools are a butane torch and a soldering iron. Also, isn't that how I got into this mess in the first place?
Lastly, a related question:
In the final steps of repadding, I know I need to reheat the pad cups while they're on the instrument so that I can make fine adjustments. I can't find anyone discussing repadding plastic instruments specifically and I'm worried that I may need to proactively take some steps to prevent damage from heat transfer through the metal where the pad cups are small and close to the posts. Am I being silly? Was it just because I applied direct heat to the post that I caused the original problem?
Thanks!
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Author: Chris P
Date: 2021-01-11 13:44
The immediate area by the thumb tube is notoriously weak and many plastic clarinets will crack there.
The problems are made even worse as plastic will shrink and expand a lot with temperature changes compared to metal which is relatively stable, so when plastic gets cold, it will shrink and the metal thumb tube will put stress on the plastic. You also have two toneholes (thumb tube hole and side F# tonehole) at the same level within close proximity and that will also be a weak point where the joint can crack.
Another plastic clarinet that has been known to break at this same point are Artley/Armstrong clarinets. They used to have a plastic thumb tube but changed to a metal one and that caused more of them to crack. The older plastic thumb tubes expand and contract at a similar rate to the plastic joint and that puts far less stress on the injection moulded joint.
In essence, plastic and metal just don't mix. If you can successfully weld the crack, then by all means do that - otherwise it's often a lost cause and better to replace the top joint. As well as the weld, you can mill out slots and fit ties across the cracks to reinforce things (like butterfly joints), then hide the ties with filler.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: DMcCool
Date: 2021-01-11 15:59
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Thanks Chris. The clarinet was very cold which may have exacerbated the shock of heating the post.
In this case, the crack does not extend to the metal thumb tube, but rather extends through a number of different posts which presumably were weak points for the same reason.
Do you have tips on attempting a weld? I've attached pictures that better demonstrate where the crack occurred.
Any links to where people have fit ties across the cracks?
I think you're right that if the weld doesn't succeed, I'm likely better served by just replacing the top joint or finding another cheap clarinet with which to practice, so it's largely academic at this point.
Post Edited (2021-01-11 16:03)
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Author: Chris P
Date: 2021-01-11 17:06
I haven't seen butterfly joints used even though it's a viable repair, but have seen metal ribs screwed across cracks which were either set into slots milled across the crack or just screwed to the surface and left proud.
I don't like the look of that crack, but it's good to see if it can be fixed. I'd look for a donor clarinet - probably one with a broken lower joint socket or tenon but with a good top joint and transplant that onto your clarinet.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: DMcCool
Date: 2021-01-13 12:29
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An update:
Cleaned the Vito Reso-Tone 3 with alcohol along the break. I put some MEK (methylethylketone) in a small glass jar and painted it along the crack using a non-plastic-haired paintbrush. I waited for it to dry, painted again. Waited for it to dry, painted again. Then I washed it off with water. The crack is still visible, but when I apply suction along it, I can no longer pull in air.
In theory, the next steps ought to be dissolving some black ABS (like a lego block) in the MEK and painting over the crack so that it fills the surface, then sanding it down.
It's not a pretty process. It's unlikely that I come out of this with a clarinet that looks as good as new, but initial work looks like it just might play.
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Author: m1964
Date: 2021-01-13 20:59
It's probably too late, but would it be possible to apply slow drying crazy glue and just suck the air out of the joint in order to pull the glue in ?
In any case, since it was a trial clarinet it served its purpose.
Did you use a soldering gun or a torch on that rod screw?
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Author: DMcCool
Date: 2021-01-13 22:00
I think that method might work, but I imagine it would require having the pads on, and working around them to get at the crack might be difficult. For a crack that's quite clear of all the keys etc, that might be a good way of handling it.
For the rod screw, I used a torch. It's easy to imagine that a soldering iron would have had better results, but since I was applying the heat directly to the post, it may well have been too much either way.
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Author: PeterD
Date: 2021-01-16 18:16
An interesting post please let the members know how you get on with it Thanks
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