Very tight corked joint

[oleorezinator]

Try the freezer.

[paddler]

Ahh, Delrin! That will teach me to be more careful reading the original post before replying! I just assumed it was another swollen wooden tenon. Sorry about that!

At least with a Delrin flute you are less likely to do damage trying to force the joint apart. Aside from trying the freezer, you could also try heat or solvents to loosen glue that is intended to hold the cork in place. That might help it slide apart. It is notoriously hard to glue things to Delrin. The cork glue has probably slipped due to the friction of an overly tight joint and caused the whole thing to jam up. Be careful not to over heat it though (check the Delrin spec sheet).

As a long term fix you could try tightly thread-wrapping this tenon, soaking the thread in beeswax. This will probably stay in place better than cork glued onto a Delrin tenon.

[busterbill]

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

I have one of the original M&E flutes from decades ago. It is a polymer, possibly delrin. I am not sure of the genesis of the material. But it does not have any cork or thread and seals just fine.

I was sent, along with the flute, a small container of toilet seal. Which has truly lasted forever since I don't think I ever used it. Though I do know the shelf it is on.

[dcopley]

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 can at least try to speak to that. Currently we use Delrin to Delrin joints on the 3-piece flutes where the top tenon joint also works as the tuning slide. It's not practical to cork the top tenon joint because the tenon would end up too thick and would disrupt the acoustics (Same principle that Terry McGee has explained with reference to his Minimum Disruption Tenon where the cork is on the inside of the socket). For a while (though not at the moment) we used cork for the lower joint and they all seem to be working fine and lasting well. From a manufacturing point of view it generally takes more time to make the all Delrin joints versus the corked joints. Getting the right fit on the all Delrin is very slow as it has to be an exact fit and you have to work around the thermal expansion of the Delrin (basically have to make sure the two pieces are the same temperature before you can check the fit). And as Geoffrey Ellis pointed out, once you make the fit too loose you have the option of converting it to a corked joint, though we usually are able use the piece on a different flute (it helps that we make them in batches).

For Delrin flutes with a metal tuning slide we generally cork all of the joints in order to keep the design and appearance very much like a blackwood flute.

My suggestions for Andro's problem with the stuck joint have mostly been covered by other posts. One possibility is that the cork has swelled because of moisture, so drying out for a day or so may help that. I would not try applying any heat, but just keep it in a warm dry place. The other possibility is to try refrigeration which can work by shrinking the tenon, but only if the socket is tightly constrained by a metal ring. I would keep the temperature above freezing since you don't want to freeze any moisture that is in there. Finally be super careful with any twisting efforts as you don't want to damage the keys or key mountings. A pair of grip gloves can be very useful for this.

[busterbill]

I can at least try to speak to that. Currently we use Delrin to Delrin joints on the 3-piece flutes where the top tenon joint also works as the tuning slide. It's not practical to cork the top tenon joint because the tenon would end up too thick and would disrupt the acoustics (Same principle that Terry McGee has explained with reference to his Minimum Disruption Tenon where the cork is on the inside of the socket).

Partially hijacking the thread here. On a side note, there is at least one power player here in Chicago who was spreading the gospel of tuning his Olwell flute a bit at the tuning slide and a bit on the tenon side of the barrel in a deliberate attempt to create turbulence inside.

I did it for awhile, but didn't notice any great difference in sound.

But back to the topic. If all else fails, depending on where you live you may be close enough to a band instrument repair person to get some help. Ask up front how much they charge. It should not be much. I'm sure they've seen this with grade school kids and clarinets.

[Andro]

Hello All,

Thank you all for the excellent suggestions, pored over by me at great length. Heating did not help, nor did drying out. Freezing did not help either. All great suggestions.

The pizza and Guinness and large thanks must go to Dave Copley (we'll send it over from Australia). I bought a pair of grip gloves for A$2.80 from our Daiso store here in Melbourne. Not only did the gloves fit my large hands (unusual for these Japanese department stores) but the grip was so effective that it came apart with no stress.

The issue was that the cork was simply too large for the socket, and will need sanding down.

Problem solved, and considerably cheaper than flying the flute back to Ireland. Again, my gratitude.

These gloves are going to be part of my toolkit from now on. Here's a photo to see the flute, the cork, and the gloves.