The Curta Demo Collection

Last Update: February 25, 2003 -- THE CURTA REFERENCE

As far as he knows, this is the only demo set of the world. He bought it from an ex-co-worker of CURTA Liechtenstein. Later demo sets came with a cut model in a green box.

Here's an amazing find... A Demonstration Model Curta!!! (click on the picture)

It was originally owned by Nils Bongue from Colombia, South America. Here's his story:

Back in 1955 I was working with a major stationary and office supplies company in Colombia, South America.

Among the items we sold were the FACIT and CURTA calculators. Due to ever increasing import restrictions, aimed at building up local industry, we were authorized by the FACIT people to set up the first assembly plant out of Sweden, which I run until 1963. A similar project for the CURTAS was not viable, so the distributorship was dropped and the company having no further use for it, let me keep the demonstration unit.

BIG NEWS!!!

The Bongue Curta Demo S/N# 29208

The new owner of the above Demo Unit generously allowed me to have the unit for almost three weeks! He wanted everybody who ordinarily would not have the opportunity to understand the Curta to benefit from the pictures on my Web site.

It was an amazing experience and during this time I took nearly 100 film and digital pictures of the unit. I also experimented with digital video but that needs a little more work before I put it on the Web. I learned 95% of how the entire unit worked and made a CAD drawing of the mechanical "logic" of the unit. The Demo unit revealed enough of the upper mechanism so that I could finally see how the carry and carry clearing mechanisms (for both the result and turns counter) worked.

Some day I hope to find a unit in poor condition that I can fully disassemble and document all of the pieces and their interactions. Ideally I'd like to make a poster of the exploded view of this amazing device for all to enjoy. Click on any of the thumbnail pictures below to see a large version... enjoy -Rick-

Here's a picture of a Demo unit that was sold in an auction in Germany. Thanks to Skip Godfrey.

S/N# 24655

A third Curta Demo has surfaced. It belonged to Steve Vick's Father. His dad worked for the A. Lietz Co. for about 30 years. During that period, they were headquartered in San Francisco and Oakland, and engaged in the manufacturing of surveying equipment, and the importation of drafting equipment. Curta was one of the lines they sold. His father told him the Curta was extremely popular with the surveyors and engineers he called on, and he sold hundreds of them.

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Christensen Demo Curta

This factory designed Curta demonstration kit consists of a see-through, fully operational Type I calculator with ten sample components and subassemblies. These items reveal many unique aspects of the extraordinary Curta mechanical calculator. All components are nestled in a beautiful fabric-lined display case. The latching case is covered in simulated leather with silver lettering identifying the company that manufactured the Curta, Contina AG, and its location in the city of Mauren, Liechtenstein. The wording on the case also mentions the joint international customs arrangement that Liechtenstein has with Switzerland.

An estimated 25 kits of this style were made. The Curta body is serial number 8651, which indicates it was made in late 1949 or early 1950. No kits of this style having a lower serial number have been identified. Several easily discernible features are indicative of its early date of manufacture: the Curta body has a low profile dome crank with an off-center retention screw on the knob, the baseplate screws are blackened brass, and the clearing lever is attached with a screw and nut (rather than a rivet). The outside of the 24 cm x 20 cm x 7 cm (9.5" x 7.9" x 2.75") display case is dark green, not the light green color used in later years.

All the original components of the demonstration kit are present, including the removable gears on the sample transmission shafts. The upper carriage subassembly includes all seventeen indexing balls, a spider spring, and a main bearing sleeve...items which were not supplied in later kits. Within the knob of each setting shaft sample there still resides a spring and indexing ball. The two central shaft samples do not have a hole for a step drum taper pin, authenticating the originality of the components.

The Curta body is in excellent, as if new, condition. This is remarkable considering it is 53 years old and had been handled by many people during demonstrations. All hardware components are extremely clean, with minimal tarnish on the brass and aluminum. There is no visible corrosion on the "ten-carry block" retention screws (which often betray improper storage conditions by exhibiting fungus-like corrosion). And there is no accumulated dirt within the knurled finger and hand grips, or within the etched digits and markings.

There are no worn or bent items. The central shaft within the Curta body is straight and true. The clearing lever is flat and level, it pivots without rubbing the clearing plate, and it properly engages/disengages from the locking pin. The fine gear teeth in the "zero positioning/anti-reversing disc" are all present and in flawless condition. Everything is properly lubricated and in perfect working order. The entire mechanism operates as smoothly as it did when it was manufactured over 50 years ago.

Here's another picture of a unique Demo unit that Skip had.

Here's a picture of a Demo unit that appears on the web site: http://www.waldbauer.com/shop.php

Watch out for fake Demos. Here's a perfect Curta on January 16, 2003.

Here's the same Curta on February 8, 2003 that's been cut-up to look like a Demo unit. Notice that this machine does not have the machined opening in the top carriage that reveals the tens carry mechanism.