The Curta.org Bulletin Board

[defrag]

I just recently acquired my first Curta, http://gamefreaks.net/defrag/personal/curta.html & have a some questions if you please:

1. I can only turn the carriage to number "6" when it is actually numbered through 11. Why? Is it because they used the same carriage in the Type II's?

2. What is the up arrow on the barrel between the reversing lever & the most significant setting knob? It points at nothing no matter what position the carriage.

3. Does anyone use the decimal markers as thousand(s) place holders? I'm wondering why there are 5 markers on the top & 3 on the bottom when if used as "decimal" markers only, you only need one. I assume this may be the reason for the black & red setting knobs on the Type IIs, eh? ..to help more easily visualize the places.

4. I notice that the manual states the when I pull up on the operating handle for subtractive operations, the sleeve should be red or white; mine is metal. On which units did the red or white sleeves appear?

5. The lettering on the bottom plate is horizontal without arcing. This seems to be indicative of the change toward the late-model units such as the Type IIs. Were there any Type IIs with arcing lettering... or why isn't my "straight" lettering indicated as such: http://www.vcalc.net/SpecialCurta/Curta-2185-5-1024x768.jpg Did anymore Type Is exhibit arcing letters after my serial #39172? Is my unit rare?

6. I realize the difficulty in accurately dating Curtas, but there is a discrepancy between http://www.vcalc.net/cu-date.htm & http://www.curta.de/kr36/index.htm They indicate October 1958 & August 1959 respectively. Which might be more accurate & why?

7. Are there any other displayed errors besides the 10's carry mechanisms failing that would indicate units in need of adjustment or repair? What do I watch out for? Is there a good computation documented for just such a purpose as testing proper adjustment & hence, resulting accuracy?

8. The reversing lever markers on units predating mine are slightly confusing (2 arrows pointing in the same direction & 2 pointing at each other); what do they mean, add & subtract?

9. What are the diamonds listed between the digits on the RR on the Curta II depicted here: http://i12.ebayimg.com/07/i/000/b9/1c/6033_3.JPG

10. Working with computers I often need to multiply by the powers of 2 such as: entering 2 into a normal calculator, then times (*), & equals (=) as many times as is necessary to get 2, 4, 8, 16, 32, 64, 128, 256, etc. Is there a method by which I can duplicate this calculation with my Curta?

11. Where can I obtain the Tables as quoted at http://www.isi.edu/~finn/curta/curta.html under Cube roots: "CURTA users who have at their disposal our CURTA Tables may, by use of these tables, obtain a cube root correct to 5 figures by means of an addition and one subsequent multiplication. These tables will be forwarded free of charge on application to our headquarters."

12. Lastly, my Curta only came with Computing Examples for the CURTA Calculating Machine booklet. I see nowhere documented which models "officially" came with which manuals. Would you please elaborate to the best of your knowledge on this? I wonder if I should purchase what could be the missing manuals for my unit in order to complete the set if you will. Not to mention having the information to complete any other Curtas I may buy in the future.

Thanks in advance for your time; I'm educating myself about these fine instruments & have read as much as I can find. I'm relatively certain these will be the bulk of my questions for the forseeable future. There were just some gaps in my knowledge based on what I found to be or not be available.

TIA

P.S. Boy those bottom plate screws ARE fun to get back in aren't they!?
_________________
DeFrag ><((°>
http://gamefreaks.net/defrag/personal/

[Jack]

Please see http://curta.org/phpBB2/viewtopic.php?t=22 regarding the "limited" carriage positions.

The unpainted reversing indicator band was changed sometime in the early 60s. There never was a "white" band...just the brilliant aluminum. For a short time there was an orange band, then a fluorescent orange band, then a fluorescent red band, and so on.

The printing on the bottom changed from time to time. Your Curta is not rare because of this.

Dating a Curta is always +/- a year or so. Fewer machines were made per month in the early years.

Sorry, but there are no specific calculation tests to confirm proper operation. There are mechanical stress tests (axial, radial, and yaw) to determine spacing and tolerance settings. These test are performed during a cleaning and service of the machine. If the Curta seems to be working, it probably is.

Contina changed the reversing slider symbols over time. The functionality did not change.

Someone put the diamond indicators on their machine. Nice job, BTW.

No "power of 2" short cuts.

I have no information about the tables you mention.

Manuals are as they are. Things changed over time, but slowly. Contina supplied the Type II with Type I manuals for many years. Most documentation records are available on eBay. You'll have to be patient to get some items.
_________________
Jack Christensen
Timewise
32 Old Barn Road
Hawthorn Woods, ILLINOIS 60047
USA
847-550-5052 (evenings)
curta.info@gmail.com

[defrag]

Thank you Jack.

Why are there 5 decimal markers on top & 3 on the bottom of a Type I? Are they used to delineate thousands place holders or something?
_________________
DeFrag ><((°>
http://gamefreaks.net/defrag/personal/