The Pentel Multi8 leads have a crimped metal retainer piece at their rear end to keep them from completely falling out of the opened clutch.
Which other leadholders have used such a retainer in the past?
Apparently, the Mars Technico 780 used a metal sleeve (not crimped on) to achieve the same goal, in the 1980s. It appears you just press the lead into the sleeve.
It was specifically advertised in 1982, the same year the Multi8 was first sold.
Do you happen to have images of them? I looked it up, and even in disassembled photos, I can’t spot any retainer. Maybe I have bad search results or I misidentify the retainer as something different
Uni has a little plastic ring in black colour acting as a retainer. It is hard to spot in the pictures, but it is there. Tiny little detail enhancing the already extra fine quality of their lead.
The metal retainers definitely go back to at least 1955, as they are mentioned in this Staedtler patent of that year:
Machine translation of introductory paragraphs from OCR text (i.e. not very good):
It is known for such pens to provide the refill at its rear end (the part not used for writing) with a metal clamp. When the refill is pushed out, this clamp engages the clamping pliers within the refill holder, thus preventing the refill from falling out.
The invention involves replacing the metal clamp with a lacquer coating of appropriate length and thickness.
I have not yet been able to find a patent for the “original” metal crimped version. Maybe it was not by Staedtler, so wider keyword searches might be needed, assuming it was patented at all.
My Uchida Drawing holder came with a plastic retainer around the lead. I don’t know if it was initially provided with the lead holder, sold attached to the lead or added afterwards by a previous user.
