Model B - next step, cleaning the mechanism

This Comptometer Model B mechanism had collected an amazing amount of dust and debris. Amazing, because there are not many openings for dust to enter the case of a Comptometer.

It will have taken more than a century, but very nicely settled in dust-towers on some of the rods. Also a lot of debris had settled on the shelf of the bottom slats. This is pretty common, probably dirt that enters via the keystems and perhaps bits of cork lining.

Using a brush, most of the dust and debris was carefully removed. (Unfortunately not quite carefully enough - one small torsion spring fell out of the mechanism! Jolly tricky to get it back into the carry/suppression levers arrangement. Note for next time; brush even more carefully!)

With dust removed, there is some tarnishing, but almost no rust. The carry-suppression of column 8 did not work. Some gentle bending of the 'leg' of the supression-tab was able to fix that.

All the keys had of course been removed. This is fairly simple, unhooking the spring allows the 'wishbone-lever' in the bottom to tilt. This then releases the curved bottom tip of a keystem, allowing it to be lifted out. The keys were kept per column in numbered bags, i.e. all column 1 keys in bag 1.

All were cleaned in the usual way for these. That means, first fine steelwool to remove dirt and rust from the stem. Then wash in lukewarm water with a bit of dishwashing liquid to get rid of steelwool particles. And then a stiff (nail)brush to clean the keys. The lukewarm water will soften the dirt, acculumated grime of decades (century). The picture above flatters the cleaned keys perhaps a bit; they are still grey. But even if not half-as-white as celluloid keys, they are better and no longer dirty brown.

The missing white of several zeroes on the number wheels were re-touched with a light brown latex paint. Starting with cream and adding brown, yellow and black ink until it's a reasonable match.

Compared to later models with the controlled key feature, this mechanism is very open and empty on top. Noticeable is the solid actuating bar that pushes down all the rocker-arms forthe (noisy!) clearing.

A few levers needed to be lifted back onto a notch, but everything seems to be working as it should. Also visible on the frames are bits of cork where the metal had fused to the lining. Ready to be fitted with its top-plate again to fit keys.