A while back, I managed to snag the little instruction booklet that goes with an erly 20th century Dennert & Pape sliderule. In addition to the explanations on the use of the 'Normal' sliderule, it also contained a chapter on the 'Kubus' sliderule.
Guess what turned up.
Somewhat worn and damaged, this sliderule came in a small lot. It has a replacement cursor or runner, but otherwise it is period. The original would have had a narrower aluminium framed single-line cursor. This three-line cursor looks like a late thirties to early forties item, but of course fits this rule fine.
The early Dennert & Pape sliderules have a year code in the well; this specimen was manufactured in 1920.
Very plain, simple sliderule with only added the E and F scales (according to the invention of Max Rietz). The well is plain with only the German patent number for the metal tensioning plate design.
The metal tensioning plate was rather rusty, now cleaned up. The label with conversion tables is quite unreadable. From what remains, it contains the conversion factors for many measurement units that are long obsolete - such as the Prussian 'Ruthe'.
The scales were cleaned up first with a rubber eraser and then a light steel-wool polishing. The three tensioning screws all needed loosening, as the rule was keeping the tongue in a very tight grip (not letting go!). A small snippet of lacquered cream-coloured paper fills in a missing corner of the right-end of the D scale - still visible as off-colour, but less jarring than dark wood.
Now with an actual 'Kubus Rechenstab', I can continue with section II of the little manual! :-)