Metal Onoto Shank Retaining Pin

[Pen_Padawan]

Dear Onoto Guru's,

I have a metal Onoto that needs service, but the plunger is frozen (see photo, that's all that will move). But since it has a metal Shank (plunger knob) I do not know if there is a shank retaining pin. I have repaired a few Onoto's; remove shank pin, replace cork seal, replace plunger washer but with no shank retaining pin how does one disassemble this metal pen?

If any one know's how to disassemble a vintage metal body Onoto plunger pen, please let me know.

Thanks.

[northlodge]

That the rod does not extend fully will almost certainly be due to the seal having solidified. Removing the section and 'breaking' the seal will resolve this.

 

You then have two different approachs available to you:

 

1. Remove the retaining pin - which you are suggesting is difficult to locate

 

or

 

2. remove (by unscrewing) the end of the rod which seats the seal. This will permit the rod to be removed entirely from the base of the barrel.

 

You can the replace seal / corks etc without removing the endcap

[praxim]

Yes, the seal has fossilised.

 

Many older Onotos had a pin holding the plunger cone on the rod, in which case it will not be possible to unscrew the cone unless you can reach that pin, normally meaning that you must take off the plunger knob. Try unscrewing the cone first (LH thread).

 

Have you tried separating the overlay from the knob? It should only be pushed on.

[eckiethump]

Using a lot of heat the turning knob overlay, it's a tight fit, glued on. The problem then is finding the retaining pin, perseverance and our old friend patience. Alternatively, use the Arthur Twydle method, not removing the turning knob, split cork barrel end seals, and replacing piston seal from barrel front end.

I prefer Viton "O" rings, rather than cork for barrel end seals, so always remove the turning knob.

Other than on Onoto Minor models, where he celluloid turning knob is "pressure"? fitted. The rod on these have no flange at the piston end, so the piston assembly can be removed from the front end and the piston rod be pulled fully out to the rear.

[Pen_Padawan]

Hi Gents,

Thank you for your advice. I explored the end knob overlay idea and sure enough, it’s a metal overlay glued on. But WARNING: I warmed up the end and pulled on the metal overlay, the glue broke and the metal overlay came off but as this happened my grip crushed the thin metal overlay. So I will be able to bend back into a round shape but I hope the creases will come out. Underneath the metal overlay is an ebonite knob with retaining pin. Thanks again.