How To Shrink Cap (To Make Thread Tighter)...?

[jpk]

Hi,

 

I have an Ultraflex safety pen with a nice old nib. It works and I like to carry it on tour. Only the cap thread is too loose, so sometimes when closing the cap I over-turn it. I checked the cap with removed end plug and can see that the thread is too loose so no wonder that I can't close the pen tightly.

 

I want to make it tighter, so I thought the best way is to shrink the cap a little bit where the thread is: can I do this with strong o-rings and boiled water?

 

Best regards!

[FarmBoy]

Better to stretch the barrel a bit.

[fabri00]

It is difficult for your pen as the thread is in the upper part of the cap, but normally a non-invasive method is applying some strips of tape for electricity in the thread inside the cap.

This make the screwing of the cap a bit more tight.

Again because the thread is in the upper part of the cap, I would not suggest to heat it.

[EBUCKTHORN]

Following on fabri00's suggestion,you'd probably want very thin tape and not much of it. Perhaps narrow strips applied perpendicular to the threads? In addition to the vinyl electrical tape, perhaps good quality masking tape (even though its intended application is only temporary). "Teflon" plumbers' tape might work too but it could be more difficult to apply.

[jpk]

Thanks for the advice. I took a very thin piece of paper and soaked it with shellac. Wanted to stick with traditional materials. Hope that works: if not, I will send it to a pro to have the barrel stretched / the cap shrunk. Does anybody know who can do this in Europe?

[fabri00]

In this case shellac is much complicated than a piece of tape, in case you have to remove it.

[CS388]

I'd be tempted to go the shellac route, as a first attempt. I don't know if you need the paper? Just try building up the shellac, making sure you keep the thread route viable. If it doesn't work, you can use heat to remove it.

 

Of course, removing (and applying) may be difficult if the threads are deep inside the cap. Alternatively, you could try the same method on the barrel threads, unless it is too unsightly, or affects your writing grip?

 

Good luck.