Jack Christensen repairs CURTA calculators. I've known Jack for
many years and can highly recommend him.
Here are a few questions I asked Jack:
What do you charge to clean a Curta?
Typically $115 to $280, depending on the type of Curta [Type I or Type II] and the
work involved. In those situations where only the upper carriage or the main body needs
work, the fee will be at the lower end of the price range. More often than not, the
entire machine needs a complete disassembly. It is my preference to thoroughly clean
everything, so the charges are usually toward the upper end of the price range. If a
full restoration is needed, the cost may even be higher. If something internal is bent,
out of adjustment, or broken, the entire machine usually needs a complete disassembly.
What do you charge when repairing a Curta?
I charge $65 per hour of my time. It seems my hours are about 90 minutes long,
however, because I rarely finish in the time I originally quoted. Extended
repair time is absorbed by me.
What spare parts do you have? Are they expensive?
I actually have many hundreds of new original Curta parts. Most are for inside the
instrument, though. I use them when I do general cleaning and repairs. Outer body
pieces, replacement cannisters, and external parts that are easily damaged or
broken due to abuse are not generally available, although I do occasionally locate
some these items. Sometimes I have to fabricate a part, or repair an item as best
I can. Obviously, this takes time, and the cost is high.
Parts costs are charged as the traffic will bear. I usually try to be blunt about
this to the Curta owner, often telling them that a severely damaged unit is best
sold as a "parts Curta". Unfortunately, I've sometimes had to tell this to someone
who wanted to repair a Curta looked upon as an heirloom. What to them appears to
be a minor issue actually turns out to be a major problem (e.g., a crank handle
tilted downward is due to a broken main shaft).
Costs for both a cleaning and typical repair is often between $150 and $250. I think
the most I ever charged for a repair was about $500...there were many serious problems
with the machine. Generally, when the price gets to be above $300 many people simply keep
the damaged Curta as a memento.
Can you replace a clearing ring? What costs are involved?
Plastic clearing rings are available. I have several new ones, but I typically do not
sell them separately as a spare part. Rather, I install them during a general cleaning
and repair. I can modify a Curta that originally had a metal clearing ring to allow a
plastic clearing ring to be used. There are special rivets for this purpose, which I have.
Metal rings are more difficult to replace. As with the plastic clearing rings, I will
only install a metal clearing ring during a general cleaning and repair. It takes a
special tool to properly swage the rivet in place. [Editor's note: Very old Type I
clearing rings were held on with a screw and nut. The nut was crimped to the screw threads
below the clearing plate. Don't turn the screw! You'll break the screw and/or strip its threads!]
I have only a very few new metal clearing rings for both the Type I and the Type II. I also
have used metal clearing rings [that were removed from damaged Curtas] for both the Type I
and the Type II. The new Type I metal clearing levers are so rare that I will only install
the ones I have on very old or very special machines. The cost for a new Type I clearing
ring is extremely high. The rivets needed to install a clearing ring are special too, but
I do have a few.
Jack's company, Timewise also manufactures a line of rally
equipment for TSD competition. The units include TSD computers for running
in a Computer Class, units designed for Odo Class competition, and
competition and checkpoint clocks. Jack can be contacted for special-order
equipment or particular modifications desired for Timewise equipment. Jack
also repairs older Zeron equipment. A wide selection of sending units are available.
32 Old barn Road
Hawthorn Woods, Illinois 60047
(847) 550-5052 (evenings)