Thanks very much.
A steel rod was no bid for longevity. I have the impression you made the new rod thicker, 3 mm, or is it still 2 mm? It looks like the pen was made without shut-off?
That is a rarity. With the pen being close to a one-off, I wonder whether there was some in-house joke about numbering the nib!
Certainly it wasn't in this case: as I said the rust at the end had expanded and split the small BHR threaded end.
The new rod is 1/8" - 3.2mm the same size as the normal BHR/Steel rods and so I can use the standard corks that are buried in the end of the barrel, held in place with a big threaded plug: Here it is with a standard one for comparison:
No, there is no shut off so it's like an Onoto Minor and must be overhauled in the same way. The knob is fitted to the rod with a RH thread and retained with a lock nut - buried inside the knob.. Tracy Tools helped by identifying the thread that I expected to be 8BA but was in fact 2/56 UNC. The interior diameter of the knob is only 6.8mm so there's not much space. In the end I re-tapped a 2mm nut out to 2/56 UNC and my friend who made the shafts for me turned down a 4mm socket which just fits nicely:
I had the necessary taps and dies - any Onoto repairman will tell you that one must have LH 5BA tap and die!
When it comes to overhauling the pen (even a standard one or indeed an Onoto Minor) one would have to unscrew the seal holder from the barrel mouth and then withdraw the rod since access to the lock nut is impossible otherwise..
What fun it all is!
Edited by Cob, 17 April 2018 - 22:02.