Finishing touch now added to the restored Comptometer Model B from about 1908.
The fixed-up machine still had two replacement keys from the 1920s (amongst many other issues that it had when found). These keys were noticeably different in design appearance from the original composite keys. They are also a slightly different shape and size. The '3' keys in columns 3 and 4 in image below are these later, celluloid replacements:
After some hesitation, these two old replacements were taken off and replaced by new reproductions of the original key design. The celluloid keys were themselves already a century old and could/should be considered part of the machine's history, an acquired 'layer' of history in archeological terms. However, having already re-painted the case I decided to prioritise the overall appearance of the machine; to optimise for looking as when originally sold and first used in 1908.
(Taking off a key means taking out the complete keystem and then using the slotted wooden bar to 'hammer' the key off. Attempting to pull off a key when the stem is in the machine will almost certainly damage/destroy the mechanism.)
The earlier composite-keys are slightly different in shape from the later celluloid keys, a bit taller and a different lower section - from a different molding process and factory. The lettering is also slightly different, thinner and taller. The lettering on Comptometer keys however also varies a bit over time, per different mold or die that was made. From measurements of the genuine specimen on the machine, a 3D model was made of the composite-key design.
The new replacements then 3D printed from PLA plastic and finished with paints to mimic the appearance of the composite keys - blending in well enough to not be noticable.
The mechanism of this model B still functions flawlessly. In above picture the machine is showing the result of dividing 355 by 113; answer 3.14159 with remainder of 033.
The Comptometer Model B now fully restored - calculating like it's 1908 :-)
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