A Wonky Cap

[Rewpert]

Hey All, 

I've recently received a turned ebonite pen who's cap does not align properly with its barrel.

 

It is the green pen in the attached picture.

 

Though I'm far from an expert, both the threads on the barrel and on the inside of the cap look okay by my eye. I'm rather confused as to what is causing the wonkyness, mechanically speaking. Does anyone have any ideas?

 

Can anyone recommend a way to put this pen right? I'm very fond of the design other than this 'quirk' and would really like it to be a pen I could use on the regular. I'm open to the idea of sending the pen out to a suitably experienced pen turner or repairperson to have the threads re-cut. I would not mind if the barrel had to be shortened to achieve this. Or perhaps a set of brass threads could be made for the barrel and cap and overlaid onto the ebonite, like a 1940's Swan?

 

For the time being I have put a silicone O-ring in the cap flush against the internal ledge that butts up against the front of the section of the pen when the pen is capped. It is only as the final turn of the threads engage that the cap leans over relative to the barrel. The O-ring prevents the pen closing tightly while still allowing it to seal up well enough to keep the nib from drying out, and the O-ring provides enough friction against the section to stop the cap from coming loose. It is far from an ideal set up - capping the pen feels 'squishy', and I'm a little concerned about what the outward force will do to the ebonite, but it will have to do until I can find a better solution. 

 

All input appreciated. 

 

Cheers, 

 

'R.

 

[dipper]

On 2/7/2023 at 6:13 PM, Rewpert said:

It is only as the final turn of the threads engage that the cap leans over relative to the barrel.

That observation suggests both threads are cut on the correct allignment. Also that there is a fair bit of free-play between the threads. And that the sideways tilt is being caused by the cap shoulder or "internal ledge" being off centre.

 

More probing inside the cap might reveal the truth.

 

If you can find a pencil or similar straight rod that fits snugly in the space at the bottom of the cap cavity,where the pen nib would sit when the pen is capped, then the position and alignment of that rod at the cap mouth would reveal any lateral offset or angular misalignment.

[Rewpert]

On 2/9/2023 at 11:06 PM, dipper said:

That observation suggests both threads are cut on the correct allignment. Also that there is a fair bit of free-play between the threads. And that the sideways tilt is being caused by the cap shoulder or "internal ledge" being off centre.

 

More probing inside the cap might reveal the truth.

 

If you can find a pencil or similar straight rod that fits snugly in the space at the bottom of the cap cavity,where the pen nib would sit when the pen is capped, then the position and alignment of that rod at the cap mouth would reveal any lateral offset or angular misalignment.

 

Hey dipper, 

I'll give this a go once I can locate a rod of the right size. It's quite a large pen and so far none of the objects I've tried have been quite the right size. Will report back with results shortly.

 

I've also noticed something else: I think that the section itself might be off centre relative to the barrel, (which I suppose would have the same effect as the cap shoulder being cut off centre?) It's a hard thing to take a photo of, but I've tried my best. If you look at the photo attached you will see that on the left side the section is flush to the outer diameter of barrel threads, but on the right hand side of the picture there is a gap between where the section ends and the outer diameter of the barrel threads. Do you think this could be responsible for the cap sitting wonky when the pen is capped?

 

 

R.

 

 

 

 

 

[dipper]

9 hours ago, Rewpert said:

Do you think this could be responsible for the cap sitting wonky when the pen is capped?

Well, it could be. But the only way to find out what's wrong is to conduct a detailed check of the pen. Not an easy task.

 

Here is one more idea, to assist checking, though you do need to be gentle with this:

 

Count the number of turns used to screw the cap on and off.

Then, unscrew and remove the grip section.

Screw the empty body into the cap, using the same number of turns.

You could screw just a little further, but be cautious. The threads are engaging deeper than normal.

 

Has the cap tilted over when the empty body and cap are screwed together as described?

 

If "yes tilted", then threads are to blame.

If "no, cap and body not tilted" then the tilt is caused by contact between the end face of the grip section and a shoulder or similar structure up inside the cap.

 

I have just tried this with a Parker Duofold (not wonky). Cap engagement is 1 1/4 turns with grip section in place. The empty body and cap screwed in 2 3/4 turns very easily, and as I felt a slight resistance I backed off at that point.

 

 

[Rewpert]

On 2/12/2023 at 3:31 AM, dipper said:

Well, it could be. But the only way to find out what's wrong is to conduct a detailed check of the pen. Not an easy task.

 

Here is one more idea, to assist checking, though you do need to be gentle with this:

 

Count the number of turns used to screw the cap on and off.

Then, unscrew and remove the grip section.

Screw the empty body into the cap, using the same number of turns.

You could screw just a little further, but be cautious. The threads are engaging deeper than normal.

 

Has the cap tilted over when the empty body and cap are screwed together as described?

 

If "yes tilted", then threads are to blame.

If "no, cap and body not tilted" then the tilt is caused by contact between the end face of the grip section and a shoulder or similar structure up inside the cap.

 

I have just tried this with a Parker Duofold (not wonky). Cap engagement is 1 1/4 turns with grip section in place. The empty body and cap screwed in 2 3/4 turns very easily, and as I felt a slight resistance I backed off at that point.

 

 

 

Hey again dipper, 

 

I've given this a go. The cap screws onto the barrel with the section removed quite deeply and with no resistance. Without the section the cap is aligned to the barrel with no noticeable wonkyness.

 

I'll have another rummage around for a rod of the correct size to test the cap shoulder as you suggested previously. 

 

Is there anything that can be done to remediate a pen with these problems?

 

Thanks, 

 

R. 

[dipper]

14 hours ago, Rewpert said:

Is there anything that can be done to remediate a pen with these problems?

Yes, but only when you have figured out what is wrong.

 

This is an engineering trouble-shooting exercise.

The best "engineer" who would have the equipment to measure what is wrong, and the judgement to decide what correction work is viable, and the tools and materials to make a correction if possible, would be the original maker of the pen.

 

It seems likely that the root cause is an off centre hole at the bottom of the cap, based on the evidence so far. (Including the fact that the cap does not tilt with your O-ring inside the cap.)

[Switala]

Hello, have you tried using the black pen cap on the green one. It seems to me in the photo that they are pens of the same model. With this experience, you may be able to define the origin of the problem. I do not doubt that at the end of the cap thread, there is an ebonite chip, which was not completely cut by the tool that made the thread, a thin knife can solve it if you can see this flaw in the finish.
Good luck and keep us informed of developments in this investigation.
Best Regards

[Rewpert]

On 2/14/2023 at 3:44 AM, dipper said:

Yes, but only when you have figured out what is wrong.

 

This is an engineering trouble-shooting exercise.

The best "engineer" who would have the equipment to measure what is wrong, and the judgement to decide what correction work is viable, and the tools and materials to make a correction if possible, would be the original maker of the pen.

 

It seems likely that the root cause is an off centre hole at the bottom of the cap, based on the evidence so far. (Including the fact that the cap does not tilt with your O-ring inside the cap.)

 

Hey again dipper, 

 

I finally found something around the house that could act as a rod to test the cap shoulder - the handle of a wooden spoon - and I can confirm that the cap sits flat and straight on the wooden spoon. 

 

I was a bit worried that the only way to remediate things would be to send it back to the maker. I can't help but feel like a pedant for making a fuss over a wonky pen cap, but at the same time it is a custom pen and the cap is rather bothering me. The squishy feeling of the O-ring every time I cap and uncap the pen rather detracts from the luxury pen experience, especially with a custom pen. 

 

On 2/14/2023 at 4:04 AM, Switala said:

Hello, have you tried using the black pen cap on the green one. It seems to me in the photo that they are pens of the same model. With this experience, you may be able to define the origin of the problem. I do not doubt that at the end of the cap thread, there is an ebonite chip, which was not completely cut by the tool that made the thread, a thin knife can solve it if you can see this flaw in the finish.
Good luck and keep us informed of developments in this investigation.
Best Regards

 

Hey Switala, 

 

I have tried swapping with the black pen, however none of the parts are compatible. This was rather a surprise to be honest, as both the pens were made at the same time by a well known penmaker. I had just assumed they'd have been made to the same measurements. 

 

 

 

[dipper]

14 hours ago, Rewpert said:

I was a bit worried that the only way to remediate things would be to send it back to the maker. I can't help but feel like a pedant for making a fuss over a wonky pen cap, but at the same time it is a custom pen and the cap is rather bothering me.

 

The wonky cap is clearly a fault, and is easily seen in your original photograph.

 

I suggest that you ask the pen maker if they will fix it for you. No need to make a fuss though. Send a photograph, and ask if they see something wrong.

 

Things do go wrong sometimes. Any maker with a good reputation and pride in their own work would want to fix or replace a faulty product.

[WestLothian]

 

Hello Rewpert,

 

Your photograph of the barrel clearly shows that the threads are not cut concentric to the barrel diameter. The left side of the image has shallow threads with squared peaks and the right side appears to have deep threads with peaks coming to an acute point. This is also shown as the offset between the barrel axis and the section axis. For the section, the barrel and the barrel threads to be all on a different axis, as clearly visible in your photo, the chances of getting the cap to align when tightened would be zero - even with a replacement non-wonky cap.

 

You could take a putty or modelling clay impression from the two sides of the barrel for a direct comparison of the depth of threads. Concentric threads and section would look like this when screwed together.

 

 

Rolling the barrel across a flat table surface would also show a distinct wobble. If you have workshop tools, mounting the barrel in a soft jaw chuck you could measure the throw with a dial indicator gauge.

 

The threads could be machined away and a new sleeve fitted to the barrel in order to cut a fresh thread correctly. This would ideally be in the original green material, but black would also look fine. Meanwhile your O-ring trick would be a low risk and non-invasive solution.

 

Alistair

 

 

[Rewpert]

Long time, no reply....

 

Firstly, thank you WestLothian for your very helpful reply on this thread. 

 

As for an update on this pen; I have continued to keep in contact with the person who made it for me. They offered to replace the pen due to the wonky cap, but that has been yet to manifest in them actually making the replacement. It has been one of those frustrating situations where they will have the pen ready by the end of the week every week for months on end. I've not lost hope that they'll get there in the end - it is not the first time that I've ordered from this person, and this has happened before with them. They've always come through with the goods eventually.

 

In the meantime, I've been thinking that it might be a bit of fun to push ahead with having this pen  reworked by a pen turner in the UK. Could anyone point me in the direction of some good sorts who might be interested in taking on such work? I'm imagining taking the project a little beyond just 'fixing' the cap issue. I'd quite like to have the replacement cap threads be brass (like a post war Swan 3340), and to have a new section and feed turned to make use of a #6 Swan nib I have going spare. I'd even be open to the idea of turning the pen into a lever filler, if I can source a J-bar big enough. Anyone interested?

 

Thanks,