This is pretty much a forwarded post, original post here.
As all of their finds and conclusions came from used products, there is a chance some of their examples had been part swapped across generations, hence some of the information might bring further discussion.
1st generation: 1965 original release, 1966 Good Design Award winner.
PENTEL GRAPH MADE IN JAPAN - Inserted[1] without being fixed in place, pinless[2]
Instead of a rubber lead retainer ring, earliest versions utilized a split tip design that had a few issues and Pentel quickly switched to rubber rings.
PENTEL GRAPH MADE IN JAPAN - Molded / non-disassemblable, pinless
Presumably an intermediate version when they first ditched the split tip.
1st generation packaging - JP/EN/DE
This indicates at the time Pentel Graph has already reached the European market, but there wasn’t defect exchange service in Europe yet, as seen absent on the German packaging.
2nd generation: the internals in the 2nd generation comes with 2 sets of screws, one for the barrel and another for the nosecone. This is also the earliest generation with colored variants.
PENTEL GRAPH MADE IN JAPAN - Screwed[3], pinless
PENTEL GRAPH MADE IN JAPAN - Screwed, pinless, green
The green version seems to be a commissioned / collaborative product between K+E and Pentel.
PENTEL GRAPH MADE IN JAPAN - Screwed, pinless, red
PENTEL GRAPH MADE IN JAPAN - Screwed, straight pin
Late 2nd gen with built-in pin
3rd generation: the simplification in text markings from ‘‘MADE IN JAPAN’’ to ‘‘JAPAN’’ is the mark of the 3rd generation. Here is also where one of my personal guesses emerged, that maybe some of the pinless models did not come with a separate ball pin. Having a built-in pin is obviously a good update from a separate pin, and it is unlikely that Pentel will go back to separate pins for no reason. It is possible, however, for Pentel to ditch the pin completely (for a short time before adding it back due to consumer demands?), or for the OP’s examples have their pins broken off or back caps swapped with older pinless caps.
PENTEL GRAPH JAPAN - Screwed, pinless
PENTEL GRAPH JAPAN - Screwed, straight pin (no pics, but verified such a version exists)
4th generation: the plastic at the front of the barrel where both the internals screws and the nosecone screws are, is thin and hence prone to cracking. This generation marks the change from screwed internals to inserted internals, eliminating the cracking issue.
PENTEL GRAPH JAPAN - Inserted, pinless
PENTEL GRAPH JAPAN - Inserted, straight pin, green
Probably a K+E collab too
PENTEL GRAPH JAPAN - Inserted, straight pin
PENTEL GRAPH JAPAN - Inserted, pinless, presumably final 4th gen productions when/after 5th gen came out
5th generation: the lead reservoir is now matte aluminum instead of brass. Late 5th gen introduced crested built-in pins that are still on PG5s today.
PENTEL GRAPH JAPAN - Inserted, pinless, aluminum
PENTEL GRAPH JAPAN - Inserted, crested pin, aluminum. This particular example has text markings 760300, if it means the year 1976, that indicates even after the introduction of the Pentel Graph 2 in 1970 and PG5 in 1972, Pentel Graph 1 didn’t immediately get discontinued and production resumed to 1976 or later.
‘‘Inserted’’ refers to the internals being fixed in place via a hexagonal part that fits the hexagonal opening in the body barrel. However, in the inserted first generation, the internals and the body don’t have hexagonal matching. ↩︎
‘‘Pinless’’ refers to Graph Pencils without a built-in cleaner pin at the rear end. At least some of them, if not all, come with a separate ball pin in the packaging ↩︎
‘‘Screwed’’ refers to the internals being fixed in place by screwing into the body barrel. ↩︎
