Recently picked up the excellent Eagle Turquoise ‘Twenty’ propelling pencil and also a Mitsubishi DEMI-.5. I like to think of these (along with the Pentel PS350) as amongst the first generation of 0.5mm mechanical pencils to be sold in the USA.
The Eagle in particular, I hadn’t known was a twist mechanism; what drew me to it was the elegant design, which felt more in character next to an early AT Cross or maybe an Anson. The 0.020 inch marking reminded me of the tiny Leroy lettering pencil that K+E importer, reportedly made by Pilot.
I pulled out my Eagle 3375 for a quick comparison. The ‘Twenty’ feels more elegant and ‘executive’. Closest in style is maybe the Pentel PS1042/5, but the lines on the Twenty feel a bit more streamlined, art decor-ish.
Lastly, the packaging of the Twenty is quite fetching as well. I pulled out the old triangular case of my Uchida Drawing Sharp E for a quick comparison of ‘deluxe’ presentation.
And here’s the more workman-like comparison of the basic Uchida Drawing Sharp S with the aforementioned Keuffel & Esser ‘Leroy’ lettering pencil in 0.020 inch.
This single lead loading method defines the twist-propel era, and probably gave rise to the ‘Automatic’ re-loading name for subsequent button-push advance designs.
I know Tombow also make the H500-0.5 but I wonder who else made twist-type 0.5mm pencils?
A search on eBay filtering results for “0.5” and “continuous twist” returns several results, Montblanc, Cross and Waterman, among others, have models of this type.
SAILOR PEN CO also has a mechanical pencil with a similar structure, which is called “cartridge type mechanical pencil”. The same goes for Hard 3.
I guess that the 0.5mm lead of mechanical pencils at that time was prone to breakage. But sailor cartridge type mechanical pencil, Hard 3 and eagle 20 do not cause the lead to be directly held by the chuck, which can protect the lead.
Later, with the improvement of mechanical processing level and the advancement of lead technology, it was possible to produce a 0.5mm continuous twist mechanical pencil like Uchida Drawing Sharp.
The Sailor / Sheaffer cartridge system and Hard3 ‘back clutch’ design certainly support the premise of relatively fragile 0.5mm leads. However the complexity of the mechanisms is much higher compared to that of a continuous twist design.
I see the twist 0.5 models as a natural progression from the old 1.18mm propelling pencils, that gradually became ‘thin leads’ at 0.9, then 0.7 and finally 0.5. The Pentel 100 and other first gen knock-types were a game changer, but carried over some old ways of doing things: e.g. only loading 1 lead at a time, but now from behind the clutch instead of from the front. Then a light bulb went off somewhere in Japan and they combined a larger reservoir with a funnel end to ‘automatically’ reload a new piece of lead versus having to manually do so. Thus, ‘automatic pencils’ were born.
The cartridge and ‘back clutch’ designs, I think, were parallel developments – both as a means to avoid patent infringement when the clutch designs were unique, and as a means to innovate and differentiate one’s products from others. The cartridge method, probably appealed to those who had tried the then new fangled ‘super fine leads’ and found them too brittle.
The mechanism of both structures is the same, both use a needle to push out the lead indirectly, but eagle is screw type, sailor and hard are push type.
The idea of the manufacturer was also a reason. Manufacturers at that time definitely wanted consumers who bought their own mechanical pencils to use their own leads.
Talking about twistaction pencils and K+E company: wasn’t there another pencil sold by K+E, the “036 «Draftsman’s Thin Lead»”, which had a twistaction mechanism, and sported the equivalent of a 0.7mm lead? I found that the reference number is 58 0366.
I don’t own that pencil, even though every once in a while I’ve seen it for sale on Ebay —I think Mr. Dan Linn lists one periodically — and I would really like to try it: I think that pencil is exclusively a twistaction-type (no memory of a pushbutton in the back).
)? And did they have own lead?