Checking the oil-level in an adding listing machine

An old Remington Portable adding listing machine (or Monarch, Torpedo or Dalton) may actually need its oil level checked. Like most mechanical lever-operated adding machines, the Portable has a dampener to control the return-stroke and prevent the machine's lever from 'snapping back'.

The dampener is the metal 'pot' visible at the back of the mechanism on the right-hand side.

The metal 'pot' contains oil, the damper-rod rotates a vane inside the pot against this oil (and a baffle) to regulate (dampen) the speed of the machine. After 80+ years, it may be that the oil-level inside the dampener is low - oil may have escaped (evaporated) via any small gap, e.g. the fit of the rod in the pot. When the vane is rotating in air instead of oil, it of course doesn't work as intended.

The dampener is fortunately designed to be topped-up. It has a filling-plug!

The screw on top of the top is the filling-plug - allowing a check on the oil-level (insert pin, dipstick) and for re-filling the dampener. This machine 'snapped back' with alarming speed, perhaps risking damage to the mechanism. The oil-level in the dampener was indeed low, perhaps half full. 

To re-fill the pot, new oil was inserted with a syringe.

After re-filling the dampener this Dalton (or Remington, Monarch, Torpedo) Portable adding machine no longer snaps the lever back when you let go on the return-stroke. It still returns quickly, but now controlled with an even speed to the rest-position - as designed.

Not an obvious thing to check and uncommon on e.g. typewriters; when an old mechanical adding machine's handle snaps back very fast and hits the end with a clear 'impact', it probably needs its oil-level checked :-)

C-key for the Remington Portable adding machine

The Remington Portable adding machine of the 1930s has a C-key protruding from the front. This C-key has a pointer to indicate the position of the next digit, pushing it to the right allows clearing an entered number from memory: marked C for Correction. These adding-listing machines can be branded Remington, Remington Rand, Monarch, Dalton, or Torpedo; and before the purchase by Remington of course Brennan. The C-key should all be identical, no matter what a particular machine is named.

(The C-key shown above is an original.)

The key itself is a press-fit onto a short stub of a stem. This stem slides into a pocket in the machine, attached to the machine's pin-bed memory. This key needs to be pulled-out to take off the machine's housing, it is only held in clamped by a spring. 

Being exposed on the front and also very easily pulled-out, these keys and/or stems are frequently missing from these adding machines.

A missing stem could be re-manufactured from a bit of mild-steel or brass of ~1.3 mm thick (probably 1/10th of an inch, but 1mm brass would also be fine). The tab that holds the key is bent 1 or 2 degrees up, tilting the top of the key slightly towards the operator. The V-shaped indents on the main ~11mm wide length that goes into the slot is where it is gripped by a spring. Below scan shows the overall shape of this stem with the main dimensions:

To replace a missing key itself, a CAD-model was made of this C-key's pointy-design:

With this 3D-model of the key and a good FDM-printer, this little pointy-key can be 3D-printed without any supports:

Printing with a small layer-height (0.1mm or less), the amount of visible layering is not too great. One or two layers of hobby-paint will mask any layering and will create a smooth, glossy key. The lettering then  picked out with white (or cream) latex paint.

(The C-key show above is a reproduction.)

Now the entry can be cleared again also on this 1930s Dalton-branded Remington Portable adding machine.

With their catalogue picture (calipers were expensive)

Browsing, noticed that both my calipers are shown on this same page of a 1950s workshop tool-catalogue. The illustrations show pretty much the exact, same instruments.

This catalogue also showed that also the little brass pocket-caliper was a fairly expensive item back in the 50ies - listed at Hfl 4.43.

The larger vernier-caliper was even more expensive at Hfl 14.29 -that's a significant amount of money (or rather, it was back then). A loaf of bread would have been around 20 cents; so using the loaves-index the vernier-caliper was a little over 70 loaves. With today's price for a loaf of 2 to 3 Euro, that translates to around 175 Euro (or Dollar) in today's money. And that's the plain steel version, nickelled it was 2 guilders more; around 200 Euro.

These two calipers were expensive instruments when new. But as now proven, these instruments can last decades. The vernier's scale is adjustable and the instrument is still quite serviceable. Expensive, but probably good value for the money :-)

Octagonal complement-key (for the Burroughs Class 5 machine)

A fancy shaped octagonal keytop without any text, a blank key.

That is the CAD-model for the top-left key of a Burroughs Class 5 Calculator. As is well-described elsewhere on the internet, this machine was a direct competitor to the Comptometer. It was cheaper and lacked the carry-suppression tabs. This means that when subtracting with the complement-method, zeroes (i.e. the 9-key) need to be added all the way to the left of the register. That is why the Class 5 has a lone 9-key over the 10th register position; as seen here in the image from 1927 advertising material (see the complete page at rechnerlexikon).

This key is only for chasing the overflowing, fugitive '1' out of the register. So it does not have any marking. It is a blank version of the same octagonal pattern as the rest of the keyboard 9-keys. This is more clearly visible in e.g. this snippet from a 1921 advertisement (see complete page at rechnerlexikon, a site btw well worth exploring!)

This key being a bit exposed at the edge of the machine probably contributed to many of these Burroughs Calculators missing this key. Or, as in the case of my specimen, the original replaced with any key that was available at the time - in this case a round, small key with the 9 legend sideways.

The original-pattern blank key is today well within capability of a regular FDM 3D-printer. So from the CAD model a mesh, then 3D printed in black PLA material. In the below image the 'raw' print straight out of the printer placed on the stem. The dimple is clearly showing the layers - printed at 0.12 mm.

With a little sanding to smoothen the dimple's layering and roughen the surface, it was painted black. With oil-based hobby-paint, the net-effect is a smooth surface that is also quite robust.

The STL is available in the Thingiverse here and the CAD-file with several mesh file-formats for printing is available here.

The finished, new key on the calculator - complete keyboard with a decently matching top-left key that is perhaps still looking a bit new and shiny: