Pinning broken clarinets

[clarnibass]

I thought I'd post about this method I learned for fixing broken clarinet bodies, tenons and sockets. It was "invented" by Gordon Palmer. I use quotes because although he invented it by himself, others have also invented similar methods (though I'v enever seen anyone doing it exactly like this). Similar methods are also used in other fields like e.g. construction, dentistry, etc.

This started as a repair for broken plastic clarinet joints, but can sometimes be used for broken tenons and sockets too (with small differences). I'll use some of Gordon's explanations in addition to mine. IMO this method can have, in some cases, advantages over the (more or less) traditional method of grafting a sleeve part for the joint. Not that grafting is a problem, not at all, but sometimes there can be reasons to use pinning. For example:

- A graft has what is possibly (or maybe probably) a weaker area in some length of the body wall, where two thinner walls are glued together. The pinning method doesn't compromise the strength of the wall for some length beyond the break.

- Pinning usually doesn't require a lathe and never required the expensive and specialized accessories for grafting, which some repairers (DIYers) don't have. BTW I do have a lathe and prefer to do pinning when both methods are an option. If the instrument is too big for the lathe (e.g. a lathe too small to hold bass clarinets) pinning is also an option.

- In most cases, pinning doesn't require getting stock plastic material and shaping it, even when it is a tenon or socket that is broken. When a tenon or socket is completely crushed and can't be used, the lathe work is still much simpler e.g. just the new tenon/socket, as opposed to working on the entire instrument. The stainless steel pins are (IME at least) easier to get and don't require work on them (other than cutting to length).

- When pinning properly, it is probably at least as strong as a graft and likely even stronger.

- Pinning is, in most cases, probably faster.

- Both methods rely on a length of material supporting the two broken parts. One uses a plastic sleeve and one uses pins (I use stainless steel). The pins are stronger than the graft.

- With some breaks, to avoid remaking a long length of the joints, a graft is done with sleeves at both sides. This creates two glues supports as opposed to only ever having one with pinning.

- Usually no tone holes, post holes, etc. need to be re-drilled, re-cut, re-threaded, etc.

I have to admit a couple of disadvantages. When a repairer is used to grafting, has all the equipment to do it and used to working with it (e.g. does grafting regularly for whatever reasons), then grafting is probably easier/faster instead of learning/trying a new method. In addition, sometimes grafting has a bit less visual evidence (but sometimes more).

The method itself is pretty simple to describe. Stainless steel pins are inserted into both sides of the break. They are glued in in addition to the glued joint. But there are some details that are important.

- I usually use around 1.2mm pins for broken bodies. I sometimes use different (thinner) diameter pin for tenons and sockets. I file/sand the pins lightly for even more reliable gluing.

- It is super important to drill vent holes for the pin holes. These are small holes at the previously-dead-end of the pin holes, drilled from the side. I use a 0.5mm drill for this. This allows the hole and pins to be completely covered and supported by glue. Without vent holes you will have air pockets and unreliable gluing of the pins, which can fail.

- It is important to get good alignment of the parts and the pin holes. This just needs good hand and eye coordination. I use a micromotor for drilling but you can use a drill just the same. I start the drilling with more rigid, shorter, 2.35mm shank micromotor drills. You can hold these in a drill too. then continue with normal drills. Avoid tone holes, posts, etc. In some situations there are tricks to help alignment.

Here are some photos of an example I just did (not complete yet). Someone asked about gluing their bass clarinet tenon and socket since the socket had some cracks. Turned out the socket very end (the metal ring area) was broken and someone glued this to the tenon. The socket still got some stress and continued to crack and break.
I gave some adive and suggestions but also warning what can happen if they try to repair this themsevles, etc. A few days later I get an email titled "Clarinet repair goes horribly wrong" with these photos:

The socket was now completely ruined. The tenon, which was fine before, now had a lot of glue on it that needs to be removed. so in this situation I've used the pinning method but made a new socket since the original was unusable.

Here are the tenon cleaned from glue and the new socket partly made:

Here is the new socket with the metal ring on it and the pins sticking out (temporarily, since they will be removed before putting the glue in the holes):

 

[jbtsax]

Thank you for that very informative post Nitai. What type of glue do you use on plastic clarinet bodies? Is the same glue used to glue the plastic to plastic that is used to secure the metal pins to their plastic holes.

Just from your description it seems that the tricky part would be to align the holes in each piece to fit the metal pins. Do you make the holes slightly oversize to compensate for slight differences in the angles or positions?

The tech that I trained with uses carbon fiber sheets to reinforce stringed instrument necks that have been broken and glued with epoxy. He also uses carbon fiber thread reinforce tenons that have broken off at an angle. The body section with the part glued back on is turned on a lathe to cut a channel around the circumference that touches both parts. Then the very fine carbon fiber thread is wound tightly around the body inside the channel while adding either epoxy or superglue. When dry, the built up carbon fiber wrap is sanded down to be flush with the body and is a nearly invisible repair.

 

[clarnibass]

What type of glue do you use on plastic clarinet bodies? Is the same glue used to glue the plastic to plastic that is used to secure the metal pins to their plastic holes.

I use a very strong slow setting epoxy. I use it for both the pins and for the plastic and they are glued at the same time. Some glues are supposedly especially for a specific material but when I've tried a plastic "welder" it didn't seem better than good epoxy. In addition, in this case the metal is glued to plastic.

Just from your description it seems that the tricky part would be to align the holes in each piece to fit the metal pins. Do you make the holes slightly oversize to compensate for slight differences in the angles or positions?

Yes, it's tricky, so there are some tricks to get this right (not really tricks but just ways to help). The holes are always slightly oversized e.g. start with 1.30mm holes if using around 1.15mm pins, usually end up with 1.40mm holes, but enlarge holes or more often part of holes (just the beginning) if necessary. In some cases there are more ways to help with alignment.

 

[pete]

I have a practical question: what about cost effectiveness?

I understand that you did this procedure on a plastic bass clarinet, but just consider any instrument. Would it be less expensive buying a new joint from the factory? Looking at the bass clarinet you have pictured, for instance, that'd reduce the repair to just removing the extra bit stuck into the top joint.

I'd also ask if this would be cost effective for one piece plastic instruments, like an Eb soprano, for instance.

 

[tictactux]

I have a practical question: what about cost effectiveness?

IME *any* non-generic (such as a spring or a pad) spare part costs 10..50% of a brand new instrument here, if they are available at all. (plastic Bundy side trill: $100. Plastic clarinet joint, unsprung: $300)
Depending on your own cost structure, repairing can be *very* cost effective.

 

[Groovekiller]

Claribass,
WOW! We have been using exactly the same pinning method in our shop on plastic clarinets. When the manufacturer won't replace a shattered tenon receiver, this is often the best solution. On soprano clarinets, as few as 3 pins will solve the problem. I've seen some of my work survive for 10 years or more.

It takes practice and good "aim" to do the pins properly, but when you get good at it, you can do 3 or 4 pins in half an hour.

 

[clarnibass]

I have a practical question: what about cost effectiveness?

It's usually worth it

I understand that you did this procedure on a plastic bass clarinet, but just consider any instrument. Would it be less expensive buying a new joint from the factory? Looking at the bass clarinet you have pictured, for instance, that'd reduce the repair to just removing the extra bit stuck into the top joint.

It depends how much the repair costs and how much the part costs. The simplest version of this repair (just gluing the parts and pins) take me approx. 45 to 90 minutes (depending on how slow I have to drill the plastic, etc.). Including the (relatively small) expensnses, total usually around $100 (and consider that in my country almost everything is a lot more expensive than USA).

With more "complicated" cases (i.e. that take longer and/or have more expenses) it will be more, but usually still way less than replacing the part. Remember that usually, a replacement joint comes with no keys, so all the old ones will need to be tranferred and it might need anything up to a full repad. I think even if you have the part in your country the repair will most likely be worth it, but especially here, the repair would be significantly less expensive and much faster. BTW that's for student models. For more expensive professional models, the repair is an even better value, since the replacement joint is MUCH more expensive and will possibly completely change the way the instrument plays.

In the case of this bass, yes, there a lot more work than just gluing it with pins, but a replacement joint (with no keys) would cost a lot more than the entire repair. Another option was a replacement from ebay, but this would also be far more expensive than this repair.

I'd also ask if this would be cost effective for one piece plastic instruments, like an Eb soprano, for instance.

It would work just fine. Gluing a one piece clarinet would be pretty much the same as gluing a joint. Cost effectiveness being the same also.

 

[clarnibass]

WOW! We have been using exactly the same pinning method in our shop on plastic clarinets. When the manufacturer won't replace a shattered tenon receiver, this is often the best solution. On soprano clarinets, as few as 3 pins will solve the problem. I've seen some of my work survive for 10 years or more.

Yeah, 3 pins are probably enough and your experience seems to pretty much proves it. I prefer to do at least 5, just to be on the safe side when it's someone who handles the instruments a bit less carefully. I don't want to risk it and 3 for me don't have enough support around the circumference of the body in certain situations.

By the way, you do also use the small vent holes at the blind end of the pin holes, right? I found this to be super important and know that this method failed for some because they haven't used vent holes.

 

[jbtsax]

I have a practical question: what about cost effectiveness?

I understand that you did this procedure on a plastic bass clarinet, but just consider any instrument. Would it be less expensive buying a new joint from the factory? Looking at the bass clarinet you have pictured, for instance, that'd reduce the repair to just removing the extra bit stuck into the top joint.

I'd also ask if this would be cost effective for one piece plastic instruments, like an Eb soprano, for instance.

For plastic student soprano clarinets the wholesale cost of an upper joint without keys runs anywhere from about $65 - $95 dollars. Of course shops with overhead need to mark up the cost of parts which is anywhere from 50% to 100% depending on the part.

Then you have the time involved in transferring the keys, which often takes quite a bit of key fitting even on makes and models that are identical. Often the pads need to be replaced as well since things have moved slightly causing the seats in the pads to leak.

The cost in the shop I worked for would be around $150 for the part and around $100 for the 2 1/2 hours labor to refit keys and replace pads as needed for a total of $250. This may sound like a lot, but to replace a quality student clarinet would cost 2 to 3 times this amount. Still it is considerably more than the cost to pin and glue the broken joint and hope the student is more careful in the future.

 

[clarnibass]

Still it is considerably more than the cost to pin and glue the broken joint and hope the student is more careful in the future.

Yes, but it might not need any "hope". I haven't had a case like this, but Gordon told me that when a clarinet he already pinned before came back broken, because someone sat on it, the pinned area held but it broke in another place near it i.e. the pinning was actually stronger than the body itself.