Very tight corked joint

[Andro]

Newly arrived, a lovely Delrin intermediate 6 key flute from McNeela in Dublin. Quite a beautiful tone and nicely made.

But the corked joints are quite tight and the top joint at the barrel went together fine with a little cork grease, but I can't get it to move at all to take it apart now. How does one loosen the joint in this case?

Andrew

[Jon C.]

Put cork grease on the tenons and it will slide right on.
BTW cheap cork grease: get a toilet seal from the hardware store, life time supply of cork grease!

[Andro]

Hi JonC, maybe i wasn't clear. The flute is together - it went on easy enough. Now I can't get it undone at the barrel joint, even with my mighty Viking arm muscles.

[paddler]

The tenon probably absorbed some water when you played it, which caused it to swell and jam in the socket,
which was already a tight fit. I would swab the flute out as much as you can, then leave it to dry out. As it dries
the tenon should gradually shrink again, and its fit in the socket should loosen off, making it easier to dismantle.
It might take a day or two. Be patient and don't be too aggressive with it! It will eventually come apart again.

Once you have it apart you could use some sand paper to carefully reduce the size of the tenon at the points where
it is seizing up. My guess is that it is the very end of the tenon that is getting jammed in the bottom of the socket,
but you should verify this.

The other thing that might help long term is to seal the end grain on the tenon so that it can't take in moisture so easily.
Wait until it is dry, then soak some oil into the end grain. This is a situation where you actually want a drying oil in the
end grain, so that it seals it up more permanently. Be sure to thoroughly clean off any excess oil that does not soak in.

[fatmac]

Never heard of delrin absorbing water.........

[kkrell]

The tenon probably absorbed some water when you played it, which caused it to swell and jam in the socket,
which was already a tight fit. I would swab the flute out as much as you can, then leave it to dry out. As it dries
the tenon should gradually shrink again, and its fit in the socket should loosen off, making it easier to dismantle.
It might take a day or two. Be patient and don't be too aggressive with it! It will eventually come apart again.

Once you have it apart you could use some sand paper to carefully reduce the size of the tenon at the points where
it is seizing up. My guess is that it is the very end of the tenon that is getting jammed in the bottom of the socket,
but you should verify this.

The other thing that might help long term is to seal the end grain on the tenon so that it can't take in moisture so easily.
Wait until it is dry, then soak some oil into the end grain. This is a situation where you actually want a drying oil in the
end grain, so that it seals it up more permanently. Be sure to thoroughly clean off any excess oil that does not soak in.

I doubt that a Delrin tenon absorbed any water, or has any end grain to seal . The cork, however, may have expanded, and indeed could be carefully sanded to insure a better fit.

[Loren]

Corked tenons on Delrin flutes......WHY????? Or threaded for that matter, all ridiculous, just ads more maintenance issues and hassles, completely unnecessary.

Anyway, sorry to hear about the stuck socket/tenon joint on your new flute Andrew. Since the flute is delrin and not wood or ebonite, you can try a combination of side to side wiggle while twisting and pulling on the separate (but not yet separated) sections. This would NOT be at all appropriate with a wood or ebonite flute as the side to side wiggle motion would likely break the tenon or crack the socket, but the Delrin should just flex, unless you are actually Superman.

If that doesn’t work the only other options I know of are:

1. Get a strong friend to play twist/wiggle/pull tug of war with you on the flute.

2. Find someone with a good strong vice, mounted on something that won’t move, who also V channel smooth vice jaw covers. If you know someone with such equipment pm me and I’ll give you details on how to proceed.

3. Take the flute to a professional woodwind repair person. They have a tool for breaking stuck slides free that could possibly work, but it’s made for metal slides and will likely mar/damage (visually) your new flute.

4. Return to maker and ask A. why the feck they used cork on a Delrin flute? And B. Will the kindly sort the problem pay the round trip shipping?

If you are able to get it apart yourself, then you need to determine what caused the problem in the first place (aside from the poor design of using cork on a Delrin flute), meaning: Did you use too little cork
grease, or is the cork simply too tight? If the latter, then you’re going to need to sand down the cork. But keep in mind, your corks will compress a bit over time, so if you sand now, they may become loose later.

In my experience, a lot of people don’t use enough cork grease, which is particularly necessary on new corks, so you may want to try greasing both the socket and the cork generously (normally you only need to grease the cork of course, but since the instrument is new this may help) then assemble and disassemble (if possible) a few times, to see if things go better. If the joint remains difficult to separate, then sanding is in order. Good luck.

[Conical bore]

I wonder if a few passes with a handheld hair dryer on a medium setting around the joint area, might soften the cork a little and release the joint. Or maybe just soften/liquefy the grease on the cork if it's hardened up.

Just an idea, don't try this if someone more knowledgeable here says it's a bad idea. I don't know anything about Delrin, and you don't want to melt your flute.

[Steve Bliven]

Corked tenons on Delrin flutes......WHY????? .... Return to maker and ask ... why the feck they used cork on a Delrin flute?

Interesting. I've owned a number of Delrin flutes over the years (Copley (2), Cochran, Ward, Baubet, DiMauro) and all have had corked joints. Some have had tuning slides but a couple have had corked tenons for the head joint (where the tuning takes place). Wonder why they use cork. Is it just because they use it on wood and it carries over to the Delrin, or that it means the turning doesn't have to be as accurate (the compressible corks makes up for any turning errors)? Or is it something else?

Perhaps some of the makers could add their thoughts.

Best wishes,

Steve

[Loren]

Corked tenons on Delrin flutes......WHY????? .... Return to maker and ask ... why the feck they used cork on a Delrin flute?

Interesting. I've owned a number of Delrin flutes over the years (Copley (2), Cochran, Ward, Baubet, DiMauro) and all have had corked joints. Some have had tuning slides but a couple have had corked tenons for the head joint (where the tuning takes place). Wonder why they use cork. Is it just because they use it on wood and it carries over to the Delrin, or that it means the turning doesn't have to be as accurate (the compressible corks makes up for any turning errors)? Or is it something else?

Perhaps some of the makers could add their thoughts.

Best wishes,

Steve

Hmmm, I’ve owned several Copley Delrin flutes (own one currently) and I’ve seen multiple others, but I’ve never seen one with corked joints. Not saying they don’t exist or even that mine is the norm, only Dave C. can speak to that.

I believe makers use cork mostly because they don’t think.

Alternately there are cases where they do use their noggin, but might make exceptions and cork the tenons by request.

Corking tenons on a polymer flute is unnecessary, inferior and wastes production time - slowing down orders and driving up costs. Plus you add the fact that corks will eventually fail and need to be replaced adding additional cost for the buyer.

[Loren]

I’m just astonished that anyone who has already gone to the time trouble of cutting hundreds of cork slots in tenons on wood flutes, and then hassled with cutting the corks to length and width, cementing them on and then grinding or sanding the corks concentric and to fit, would then want to bother with that on polymers. I’ve done those procedures thousands of times and my feeling is, I’d certainly skip going to the trouble when a much better alternative exists. Geeze just avoiding inhaling the rubber cement fumes alone makes it worth skipping.

No upsides.

[Loren]

All of this aside from the obvious fact that the vast majority of people buying polymer flutes are doing so because they want essentially a no maintenance flute, so why would you add something unnecessary that requires periodic maintenance. Plus cork grease, yuck.

OK, that’s about enough outta me.

[Geoffrey Ellis]

If I were guessing I'd say that the maker might have misjudged the cutting of the tenon or socket and accidentally gotten too loose of a fit. Rather than start from scratch (re-making the portion of the flute that was affected) they may have simply opted for adding the cork to salvage the flute.

I've done delrin-on-delrin sockets and tenons, and you do have to be very precise to get a good fit. The tiniest mistake in removing material and you have a loose joint. That might be why cork was chosen as well.

Dave Copley makes a lot of delrin flutes and I'm guessing is very practiced at sizing the joints just right, obviating the need for something like cork.

[kkrell]

I have a Dave Copley keyless D in Delrin, (3-piece) with faux ivory rings. The tenons are corked.

[fatmac]

Corking tenons on a polymer flute is unnecessary, inferior and wastes production time - slowing down orders and driving up costs. Plus you add the fact that corks will eventually fail and need to be replaced adding additional cost for the buyer.

The two delrin/polymer flutes that I bought both have cork joints, yes, they will need replacing at some time, but I could likely get away with using PTFE plumbers tape, if they became loose.