Jack Christensen

Jack Christensen

My first Curta, a Type II, was given to me in 1986 by a car rallyist. I had been given the Curta simply because it was unusable. The machine apparently had never worked properly since the day it had been purchased. With considerable time and effort...about 8 hours of intense scrutiny and as many more of considerable worry...I managed to repair the instrument. I remember looking at a pile of little parts, and wondering how in the world I'd ever get the thing back together again. But I did, and I ended up with a perfectly functioning machine. The problem had been a factory defect...a screw was too long and caused interference with the rightmost input slider.

The rallyist who gave me the broken Curta had told me the instrument was one of twenty-five bought at a used equipment auction in the late 1970's held by the City of San Francisco's Land Surveying Department. When the department updated to Hewlett Packard calculators, all the old, supposedly outdated, equipment was sold. He had paid $400 for the lot of twenty-five Curtas. Knowing this, I didn't feel too guilty about my "bargain" machine.

Shortly thereafter, realizing that the Curta had been used by land surveyors prior to the advent of HP's calculators, I contacted every surveyor I could locate in Chicago. I found a retired surveyor who was willing to sell a Type I for $125. This was great...I now owned one of each Type.

Later that same year, as word got around that I had repaired a Curta, I began receiving requests from local car rallyists who wanted their heavily used Curtas cleaned, adjusted and, on occasion, repaired. Within a year I was working on one Curta every three months. These machines were from all around the United States, but in every case they were owned by a car rallyist.

Then, in late 1989, I was contacted by Skip Godfrey, who by word of mouth, found out that I was repairing Curtas. Skip was not a car rallyist, but a collector of fine instruments and gadgets. After I worked on two of Skip's machines, he began recommending other Curta owners to contact me. A few years later, Skip told me about Rick Furr's newly posted Curta website (http://www.vcalc.net/cu.htm) where a registry of Curta owners was listed (http://www.vcalc.net/cu-peo.htm). I added my name to Rick's list immediately, where he included a comment about my Curta repair service.

My Curta cleaning and repair services eventually became well known around the United States, and in a short time I was working on one Curta every month or two. I had to search for parts, of course, and after considerable diligence and good fortune I found sources of parts in Europe and elsewhere. I also located a retired repairman who had been trained in 1954 by Contina. This gentleman guided me on many aspects of Curta repair. He was also the source of all my Curta repair tools and fixtures, as well as a large selection of NOS parts.

I now service many Curtas each month.

I've learned a great deal about the variations of the Curta mechanics as it was changed during its years of production. There have been many subtle external changes as well as internal design and material improvements - particularly during the first ten years of production.

In addition to the Curta repair service I provide, I also design and manufacture the Timewise line of rally computers and multi-split checkpoint clocks. Information on these services and products can be found at:


And check out the great 'before' and 'after' photos taken by Rick Furr of repair work I did on a very old Curta Type I, serial number 2185. Rick placed them on the following page of his web site: http://www.vcalc.net/cu-oldest.htm

 32 Old Barn Road
 Hawthorn Woods, Illinois  60047


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