What Size Is The Retaining Nut/bolt On A Conway Stewart Cap?

[chunya]

Hi All,

 

I need to remove the clip and 'stud' (?) from the cap of a CS93. Now, I recall seeing a video on You Tube where the restorer made a prong out of a screwdriver to fit on the outer edge of the nut/bolt, so I took another look. It looks like a good idea and seems to work, but the problem is that he doesn't seem to say what size cut-out he makes in the driver head. Does anyone have any idea?

I imagine back in the day CS would have had custom made tools, which I doubt you can get nowadays.

 

BTW What do others use?

Edited August 7, 2018 by chunya

[northlodge]

Well I have one of those CS custom made tools, and also a home made affair from a small cheap screwdriver.

 

Thing is whilst these are great for putting everything back together, undoing the stud can be impossible do to corrosion etc.

 

Often the easy way is to grind out the stud, and then knock the shaft / nut out from above. Then I replace the clip/stud and nut with a NOS replacement.

[chunya]

Many thanks for that northlodge, and it seems that that's what I'll have to try unless I send it away. It does make you wonder why they didn't simply use a screw head, as some other makers did, but I imagine that there must have been a very sound engineering reason.

I have a feeling that someone has attempted this in the past (maybe to replace a slightly 'pulled' clip) as somehow there is a very small crack at the very top of the cap, and this is what I want to get to.

BTW, what is the size of the nut, do you know?

Edited August 8, 2018 by chunya

[ChrisJJ]

Well I have one of those CS custom made tools, and also a home made affair from a small cheap screwdriver.

I would be interested to know the dimensions of the tools you have. What height, width and length are the two tines, and the distance between them?

 

Chris

[northlodge]

I would be interested to know the dimensions of the tools you have. What height, width and length are the two tines, and the distance between them?

 

Chris

Sorry Chris I am not that scientific. I purchased a narrow flathead (sufficiently thin to extend all the way into the cap) - the cheaper the better is probably a good rule of thumb.

 

I then found an old stud, and ground out a U in the flat head just big enough to take the stud thread. So rather than worried about sizes I worried about whether it would work. Okay it might seem this is dependant on having a stud to begin with, but these can be in different sizes (mine works in Dinkies and CS85L models)

 

 

BTW, what is the size of the nut, do you know?

 

Again I have several different sizes in my parts stock,

Edited August 8, 2018 by northlodge

[ChrisJJ]

I have some CS pens I have been trying to unscrew the caps of, for a deep clean, but have not sorted out the correct tool as yet. I did see some potential in a spanner screwdriver on Amazon for less than £2, and free postage (took three weeks from Thailand, but got here and I was in no hurry), no nothing to lose. It was too small.

 

 

As a result of this post, I tried in on a Dinkie, and it turns out to be perfect for the job. Almost made to measure!

 

 

The measurement across in total at the end is 4.3mm, and the gap between the forks is 1.5mm.

 

Chris

 

 

 

[chunya]

Hi Chris,

I saw a similar advert on Amazon, these were from China but just as cheap and again free postage. and have bought a couple in different sizes. Hopefully when they arrive (estimated 2 weeks +) If they're not quite right I can always try to resize one, which I think will be easier that starting out with a whole flat headed screwdriver.

[eckiethump]

Cap and pen should be back with you Tuesday 28th inst. ☺

Previous repair attempt (not by you, I know) had been to "glue" threaded holding jewel in place (happens a lot), this had rotted and has now been replaced, along with cosmetic works to heat distorted cap rectified.

[PaulS]

can cerfainly confirm the corrosion aspect of these nuts, as mentioned by northlodge - very annoying - the nut is brass but can't remember now if the jewel is steel or brass.

Converting a slot head screwdriver to spanning mode can be done, but it's a bit hit and miss when making size of gap, and flat heads so often have a sudden increase in width of neck as you approach the tip, and this must be ground down otherwise the thing won't reach the business end of the cap. Good to hear that there's a proprietary tool, though it seems it fits the Dinkies only. I've had some success with a nut spinner, which was the method recommended to me on FPN some time back, although I still had to grind away some of the girth of the 'socket' before it would reach the nut.

No - I don't know what the size of the nut is either. I've never ground off the jewel - it sounds hairy, and makes me think it would be very easy to damage the tassie/clip ring, though no doubt both could be replaced.

Good to hear this one has been put right.

[PaulS]

I really did have some success with a nut spinner - though it had nothing to do with C.S. - it was Waterman - and they're even more annoying than C.S., so apologies for the duff info. I did start out collecting C.S., but fell by the wayside

the numbering system seemed confusing - that's my excuse

But - back to C.S. …………….. just my opinion, but possibly better not to say "nut/bolt" - these little chaps don't have flats or hex heads so won't conform to standard jargon. Measuring these 'nuts', they do vary slightly and of the four in the pix diameters come out at 7.15, 6.35 and 6.45 mm, but if a replacement was needed then I doubt this is critical. Round is probably easier to make than hexagonal, and the spanning slot is easy, followed by threading with a small tap and die set. As can be seen in the pix, there appears to be at least two forms of 'nut' - a uniform thickness job and another design which has a slightly truncated neck on one side - this looks to accommodate clip ring variation.

Not all 'nuts' are brass - some look to be possibly a material such as hardened aluminium.

 

Aside from these 'nut and bolt' jobs, there is the plastic stud/jewel type - shown in pix - a vast improvement from the diy point of view as they are simply self-tightening (Blue-Tac or one of Ron's jewel removal tools) - assuming you can get them off in the first place - I failed to remove one jewel - despite the hair dryer and thumping on the workbench - so maybe it had been glued in.. Below the threading in the top of the cap the cavity is blanked off, usually, although in one of the pens in the picture the dead end had been drilled out - possibly to help with tightening the jewel via the open end of the cap. It appears that the open end of these plastic jewels might just be of a square shape - perhaps this was part of their manufacturing process. One of the pix shows a steel rod with squared end, and this fits the jewel opening accurately.

Pens in pictures are:- those with plastic jewels in picture five ……. 14, 58, 15 and 27.

metal jewels in picture six ……… 85L, 73, 85 and 77

 

I'll have a go at making one of the brass 'nuts' in a day or so, just to see how simple it might be, or not.

Edited August 27, 2018 by PaulS

[chunya]

Cap and pen should be back with you Tuesday 28th inst. ☺

Previous repair attempt (not by you, I know) had been to "glue" threaded holding jewel in place (happens a lot), this had rotted and has now been replaced, along with cosmetic works to heat distorted cap rectified.

 

Arrived and excellent work as usual, Eric. There was no way that I could have done it.

[PaulS]

this first effort a tad crude, but you get the idea - this one is possibly too thick. Makes you wonder why C.S. made it essential that a spanning driver is needed - to save depth in the cap, or to hinder the efforts of amateurs?

Depending on the depth capacity when the pen is capped and jewel and clip all in place, it could be that there remains sufficient clearance between nib tip and 'nut' thus allowing threaded unit to be be made thicker - so avoiding the need for a spanning driver, and a straightforward slot head one being adequate. Will need to do some measurements to see if this possible.

Making the jewel is obviously a tad more involved.

[mitto]

Thanks for sharing the pictures. Very helpful.

[PaulS]

there was a time when I frequented boot (estate) sales, and bought all manner of tools and related kit which included hordes of taps and dies, so had just the right tap for making the female thread for this item - but am certain I don't have a die small enough to make the matching male jewel thread.

As an alternative It might just be possible to substitute a steel nut - with the correct thread size - for the missing die, and force the nut onto the shank of the jewel and hope it might cut a thread ………… obviously brass being a lot softer than the steel.

I was fortunate in that someone gave me the lathe

Edited August 30, 2018 by PaulS

[eckiethump]

I really did have some success with a nut spinner - though it had nothing to do with C.S. - it was Waterman - and they're even more annoying than C.S., so apologies for the duff info. I did start out collecting C.S., but fell by the wayside

the numbering system seemed confusing - that's my excuse

But - back to C.S. .. just my opinion, but possibly better not to say "nut/bolt" - these little chaps don't have flats or hex heads so won't conform to standard jargon. Measuring these 'nuts', they do vary slightly and of the four in the pix diameters come out at 7.15, 6.35 and 6.45 mm, but if a replacement was needed then I doubt this is critical. Round is probably easier to make than hexagonal, and the spanning slot is easy, followed by threading with a small tap and die set. As can be seen in the pix, there appears to be at least two forms of 'nut' - a uniform thickness job and another design which has a slightly truncated neck on one side - this looks to accommodate clip ring variation.

Not all 'nuts' are brass - some look to be possibly a material such as hardened aluminium.

 

Aside from these 'nut and bolt' jobs, there is the plastic stud/jewel type - shown in pix - a vast improvement from the diy point of view as they are simply self-tightening (Blue-Tac or one of Ron's jewel removal tools) - assuming you can get them off in the first place - I failed to remove one jewel - despite the hair dryer and thumping on the workbench - so maybe it had been glued in.. Below the threading in the top of the cap the cavity is blanked off, usually, although in one of the pens in the picture the dead end had been drilled out - possibly to help with tightening the jewel via the open end of the cap. It appears that the open end of these plastic jewels might just be of a square shape - perhaps this was part of their manufacturing process. One of the pix shows a steel rod with squared end, and this fits the jewel opening accurately.

Pens in pictures are:- those with plastic jewels in picture five . 14, 58, 15 and 27.

metal jewels in picture six 85L, 73, 85 and 77

 

I'll have a go at making one of the brass 'nuts' in a day or so, just to see how simple it might be, or not.

 

This post is absolutely excellent information with the showing of all the CS variants for cap clip assembly on "newer"? Pens. Thank you