I present my pen refill adapter, for use in pens that take a generic plastic tube ballpoint refill, with the small tabs pre on the side, which make contact with the pen's spring. It allows this pen to use Uni UMR-109 refills (not included) or other similar 98-99mm long plastic tube type refills instead of the one the pen is supplied with.
These generic refills can come in various lengths, with three popular lengths being around: 88mm, 98-99mm and 107mm. They are around 3mm in diameter and the position of the side taps can vary a great deal. Only pens that take a longer refill can be used with this adapter.
The Uni UMR-109 refill is around 99mm long and 3.1mm in diameter.
Other suitable refills include:
Ohto - G-95NP, No.99(X)NP
Pentel - BKSS7, BKSSN5, BXS(X), XBXST5, XLRNT5, XBGRN(X)
Pilot - BVRF-(X)
Uni - SXR-89-(XX), UMR-109-(XX)
Zebra - EK-(XX), NJK-(0.X)
These refills come in many varieties of ink, from oil-based, to gel, emulsion and hydrid, so this adapter exists to hopefully provide flexibility, between your favourite pens and refills.
The adapter needs to be printed in the polished white or coloured plastics, as the smooth polished finish is functionally desirable. The refill is held in place, by the adapter, using friction. The holes around the side of the adapter are present to help with the removal of unbonded plastic powder from the core, when being polished. However, some powder may still need to be removed, with a pin or thin metal rod, before inserting the refill.
The adapter may need to be modified in two ways, to allow it to work as a replacement for any specific refill.
Firstly; the lower part of the refill (the thinner section) may need to be cut to length. A UMR-109 refill needs to be installed, then the adapter should be lined up with the original refill, so that the ballpoint tips are level, then any protruding plastic should be cut from the end of the adapter, so it is the same length as the original refill. The adapter is supplied in a length suitable to replace a 107mm refill without modification.
Secondly; the upper, wider section may need to be trimmed, depending on where the spring contacting tabs are on the original refill's body. Again line up the original refill and the adapeter, with a UMR-109 refill installed, as mentioned above. Cut away any plastic material on the adapter, that is above the upper edge of the original refill's tabs. The grooved rings on the upper section of the adapter are spaced 2mm apart and are present to help make cutting the material eisier. The position of the cut does not need to be too accurate, compared to the original refill, so using one of the grooves, that's a little above or below the original refill's tab position, shouldn't be an issue.
Cut's should be made with a sharp craft knife or box cutting blade, onto a cutting mat or other suitable surface.
Due to the very varied nature of pen design, I cannot guarantee that this adapter will work with any specific pen, although I've made every effort to make it as universal as possible.
I plan to make as many refill types compatible with as many host pens as possible, so If you have any suggestions on refill adapters, please let me know and I can hopefully make it available, depending on the relative sizes involved. I have now created dimensioned drawings of over 80 standard and obscure ballpoint, gel and rollerball refill types, so I like to think that I have a fair idea of what is and isn't possible.