How To Fix Worn Plastic Threads?

[InvisibleInk]

Hello

I have made the unthinkable error of washing my fountain pen (P75 imperial in case you need to know what material) with water which was apparently too warm. As a result the threads in section which are made in plastic are suddenly worn. It slips out as I screw in the end section.

I called a local repair shop and as soon as I said the problem he said "you washed it hot water?" So we know why this happened.

Does anybody have a solution or tip as how to fix it without having to change the section?

I know I can wrap a bit of tape or plastic or use plumber's white tape thing, but I am looking for a permanent solution to actually fix the problem.

thanks in advance

PS. Photo is not from my own pen, I just included it to make it more clear where the problem is.

Edited October 15, 2019 by InvisibleInk

[challer61]

Hard to imagine hot water by itself would cause that problem, but I am often surprised. I do not believe the threads can be restored

[carlos.q]

I've seen the section threads on a P45 "repaired" with white teflon tape. I agree that this would be your option, short of buying a new section.

 

But then again I'm not a professional pen restorer.

[Ron Z]

The threads can be stretched. Its a tricky repair. I do it, but I would not recommend trying this yourself because there is the risk of cracking the plastic, or melting it into a mess.

[InvisibleInk]

Guys thanks for your replies. I have no doubt it is the washing that messed up the pen. It was perfectly fine before and like this right after it dried.

RonZ since I can not send you the pen and there seem to be no option but to get a new section would you mind briefly or in general tell me what is involved in stretching the threads? You heat and touch them one by one (re-sculpting) them?

This is very typical of me. I am a messy and disorganized person and I always find everything easily and function perfectly. When some well meaning person organize my stuff I can not find anything for weeks.

Edited October 15, 2019 by InvisibleInk

[ac12]

You could have caused the section to shrink, from shrink cooling after the hot water bath.

Or there could have been gunk on the section and in the body, that was taking up the slop, and making it seem like it fit.

[FarmBoy]

Shrinkage.

You stretch it by heating it to beyond the glass phase transition temperature and stuffing a mandrel into the part that can act as a cooling support that stretches the part back to the original shape. Better yet if the mandrel is self expanding so the shove isn't so violent. It helps to have a lathe to make the proper mandrel and in the absence of an expanding mandrel you may need to make multiple and expand the opening in small steps. (Yeah I'm skipping over some of the parts to this...)

 

If Ron is really willing to take on such a repair I'd send it to him if replacing the section wasn't possible. A 75 section should be easily sourced.

[InvisibleInk]

Thanks FarmBoy

You are right I saw many sections on ebay for 50 to 90 dollars, but I prefer to keep the original one if possible.

What do you think about this based on your suggestions:

1. I warm the section gradually in water

2. when warm enough I screw the barrel to the section and let it cool.

3. to prevent sticking I spray dw40 or some other oil.

 

Do you think it would work? Finding the correct mandrel won't be easy that's why I thought of using the barrel itself.

[leewm]

 

>3. to prevent sticking I spray dw40 or some other oil.

 

I would use "some other oil" like silicon grease as I have had WD40 causing the platic part I applied it on to disintegrate.