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). 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 :-)
