Vintage Parker Duofold Thread Problem

[Quality Pen]

I bought this pen used and I'm having a problem with the barrel mating with the cap. Oddly? they screw together just fine when the section is not attached.

 

However, when I attach the section then it appears to hit a lip inside the cap that totally prevents any threads from attaching.

 

The actual threads have been cleaned and they don't look that bad...

 

What do you feel is a) the problem and b ) the best solution?

 

I tried to get a video to demonstrate for you!

 

 

Thanks for looking!

Edited July 7, 2015 by Quality Pen

[terim]

Could the inner cap have slipped down?

[Quality Pen]

Thank you for the response... But... Hmm, well I simply have no idea! It doesn't look like something inside can slip down.... is there anything I can do to check this particular issue?

[terim]

Other than compare it with another pen, probably not much.

[lcoldfield]

This is a common problem - it is caused by wear of the threads in cap or barrel or both. The stop inside the cap is the lip of the inner cap - it is there to provide an airtight enclosure for the nib as the end of the section bears against it.

Unfortunately, there is no easy cure for this and it will require the attention of a skilled repairer.

The easiest solution is to machine the lip of the inner cap back a little, but you have to ensure that there is still room for the nib or you will break the tip off. Another solution is to shorten the section, and yet another to build up the threads with adhesive. The first two methods need a lathe to do it properly and the adhesive method is risky as well as requiring a thread chaser to make sure that the threads are properly formed.

Laurence

[raivtash]

I just got a vintage moore pen. I really like the color of the pen. but the pen has exact same problem. The barrel wont mate the cap. But it is fine if the section is not attached. Have you solved your problem?

[Quality Pen]

I just got a vintage moore pen. I really like the color of the pen. but the pen has exact same problem. The barrel wont mate the cap. But it is fine if the section is not attached. Have you solved your problem?

Never found an "easy" solution and just set it aside until I have more time.

 

Above, lcoldfield, recommended some methods I may try as I get the chance.

[penmanila]

Not the best solution (and one others here might disagree with) but what I've done in cases like this involving my 1920s Duofolds has been to disassemble the cap and shorten the inner cap (filing down with sandpaper has worked for me). This shortens the capped pen a wee bit but it works.

[fountainbel]

Shorten the inner cap is the simplest solution, at least if the nib will not touch the bottom of the inner cap after doing so. I do this on the lathe using a finger mill ,avoiding the need to extract the inner cap

Another possibility is to expand the barrel threads using heat and an expansion collet.

In most cases the threaded part of the barrel is somewhat conical, the first 3 thread leads having a gradually increasing diameter. So i try only to expand these 3 first leads more using a slightly conical expandable bushing over the expansion collet. Doing so only the barrel bore entry is expanded and the tighter fit for the section remains behind the slightly expanded part.

I've already done this at several occasion with good results.

Francis