!-) Yes, Ecobra is not GDR; it is a Bavarian company it stands for Eichmüller & Co, Bayerische Reißzeugfabrik AG

Partially it seems very complicated what they really produced for themselves. As a student I bought dividers from them I think they really produced them. Not the same quality (and price...) as Haff but very robust. 

Hi Meine,

I also have this Ecobra 143. It is named by the way Darmstadt Spezial, not Rietz, and it has more or less a log log layout with trig on slide. For a good usage however a second C scale on the back of slide is missing so that turning the slide is no fun, which is the reason that in my opinion it is no lucky design even if it is one of the rare European models with P on slide.

On my copy so far I remember the numbers are not somehow engraved into the material, but they look out, so it is just the other way round as with normal sliderules. I did not see this on any other sliderule so far and I somehow wonder whether it is really from Germany if it is not a very late model.

Mine came in absolutely new condition. This is why I thought that it was at least bought late in sliderule era, and due to its strange way of characters coming out I thought it was simply very late made, so the last attempt to make them very cheap.

Best regards

Andreas

I got quite a bunch of slide rules and one of it had no markings at all. However, on a Sunny Sunday afternoon I found out what it was. Here I share my strategy for a 'Determination of Slide Rules'

The slide rule at hand has no markings from the brand or whatsoever and had a simple soft plastic sheet marked 'vendex techniek' (brand 'technical') -- typically 70-ies. Luckily the sheet was still with it ! I like the lower cast letters on those markings :-)

Vendex is the home brand of the Dutch V&D (Vroom en Dreesmann) department store. Vendex sold cloathing, kitchenware, computers, typewriters and school stuff under their own brand. But who made it?

The colours of this pocket-size slide rule are Nestler-like. Or was it Mantissa? Light green. omparing the colours next to eacht other only makes it more difficult -- Nestler's green isn't the same green throughout the years, printed colours and sun wearing over time alike.

The edges of the slide rule are angled -- 90 degrees sharp. More expensive, western slide rules mostly have more rounded edges.

Two indicators somehow pointing to the DDR/GDR.

Searching the database:

Searching the internet for a 'vendex slide rule' gave no results. Herman van Herwijnen's catalog neither.

Slide rule catalogues have a distinct way of writing the scales. So I searched for

'LL3 LL2 A = B CI C = D K LL1' -- an alternative is to replace the = with [ and ] to mark the slide scales. Mind the quote marks to keep the parts toghether in that order in a search engine !

DuckDuckGo and Google came with different results, pointing to the Ecobra 143.
Searching Herman's database on the ISRM (https://sliderulemuseum.com/HSRC/FULLA--Z.htm) -- just hit CTRL-F and fill in -- for the scale layout only gave two hits: The 'Ecobra R 143 Rietz' and a 'NoName' -- both were right !

* Ecobra R 143 Rietz https://sliderulemuseum.com/HSRC/08161.jpg

* NoName http://www.rekeninstrumenten.nl/pages%20and%20pictures/20041.jpg

Both slide rules are near identical in size, colour and schale order. Only the NoName has a different scaling on the back of the slide and a 15cm scale on top of the body instead of 13cm. Extending the cm scale is seen with many slide rules, so it isn't a big difference.

My conclusion is that this Vendex must be made by Ecobra. This also corroborates with the fact that the Vendex home brand was not the most expensive, but also not really 'cheap', and offering decent quality for a buck ('gulden' that era).

--

//meine

-- 
Prof. Dr. -Ing.
Andreas Poschinger

Hochschule München
Fakultät 05
Lothstraße 34
80335 München

On Sun, Sep 19, 2021 at 12:08 PM, Rod Lovett wrote:

LL3 LL2 A = B CI C = D K LL1

hmmm, have to learn how to use search engines better -- adding the '#s'

The Jakar has the same scales on the back of the slide as my NoName vendex.

Jakar seems to be Japanese, most on the ISRM made by Fuji

Curious connection between the GDR Ecobra and Japanese Jakar being the same slide rule...

TNX!
 
--

//meine

One of the slide rules I got is a Blundell Academy Duplex Model 503. The front side is just another slide rule having 'L K A [ B CI C ] D S ST T' scales.

The back however has 'M1 MONTHS [ DAYS-WEEKS 'DECREASE AND PROFIT ON RETURN' C ] D M2 M3'

The back is very interesting and is made for fincancial calculations. The M2 and M3 scale have £ (Pound) markings before the values [see Tina's Blundell 503D http://tinas-sliderules.me.uk/Slide%20Rules/Blundell%20503.JPG] The 503D in Tina's collection even calculated Pence on the M2 scale.

There is an international agreement on slide rule scales, even crossing borders of the wetern world with Russia, China and Japan (France, the older Graphoplex are an exception). But AFAIK there is no 'M scale' mentioned yet.

M scale -- measuring  money, only seen for calculating British Pound Sterling and Pence.

(if anyone knows how to use the months/days-weeks scales on the Blundell to count over the end of the year please let me know! same for leap years)

--

//meine

Hi Meine,

if you go tp Herman's Archive Search at:

https://sliderules.lovett.com/herman/hermansearch.html

and insert: #s LL3 LL2 A = B CI C = D K LL1 into the first field you get five hits including the Ecobra and a Jakar with three "No Names".

Regards,

Rod

I got quite a bunch of slide rules and one of it had no markings at all. However, on a Sunny Sunday afternoon I found out what it was. Here I share my strategy for a 'Determination of Slide Rules'

The slide rule at hand has no markings from the brand or whatsoever and had a simple soft plastic sheet marked 'vendex techniek' (brand 'technical') -- typically 70-ies. Luckily the sheet was still with it ! I like the lower cast letters on those markings :-)

Vendex is the home brand of the Dutch V&D (Vroom en Dreesmann) department store. Vendex sold cloathing, kitchenware, computers, typewriters and school stuff under their own brand. But who made it?

The colours of this pocket-size slide rule are Nestler-like. Or was it Mantissa? Light green. omparing the colours next to eacht other only makes it more difficult -- Nestler's green isn't the same green throughout the years, printed colours and sun wearing over time alike.

The edges of the slide rule are angled -- 90 degrees sharp. More expensive, western slide rules mostly have more rounded edges.

Two indicators somehow pointing to the DDR/GDR.

Searching the database:

Searching the internet for a 'vendex slide rule' gave no results. Herman van Herwijnen's catalog neither.

Slide rule catalogues have a distinct way of writing the scales. So I searched for

'LL3 LL2 A = B CI C = D K LL1' -- an alternative is to replace the = with [ and ] to mark the slide scales. Mind the quote marks to keep the parts toghether in that order in a search engine !

DuckDuckGo and Google came with different results, pointing to the Ecobra 143.
Searching Herman's database on the ISRM (https://sliderulemuseum.com/HSRC/FULLA--Z.htm) -- just hit CTRL-F and fill in -- for the scale layout only gave two hits: The 'Ecobra R 143 Rietz' and a 'NoName' -- both were right !

* Ecobra R 143 Darmstadt Spezial https://sliderulemuseum.com/HSRC/08161.jpg

* NoName http://www.rekeninstrumenten.nl/pages%20and%20pictures/20041.jpg

Both slide rules are near identical in size, colour and schale order. Only the NoName has a different scaling on the back of the slide and a 15cm scale on top of the body instead of 13cm. Extending the cm scale is seen with many slide rules, so it isn't a big difference.

My conclusion is that this Vendex must be made by Ecobra. This also corroborates with the fact that the Vendex home brand was not the most expensive, but also not really 'cheap', and offering decent quality for a buck ('gulden' that era).

--

//meine

I don't recall ever seeing a commercial circular slide rule with two cursors while I was working in telecom engineering in California for about 40 years.  I think, though, that I had to have been aware of them because I made one with special scales for carrying out a routine chained calculation involved with the design of analog carrier telephone systems.  A friend of mine made a nomograph consisting of twelve parallel scales positioned one above the other.  It's been a long time, but I think he used dividers to accumulate values as he stepped down through the scales, each one scaled to provide a particular multiplier.

I made a circular version with two cursors (arms) and twelve concentric scales.  You could move the cursors along through the values, holding first one, then the other, while moving the "free" one.  The crude cardboard unit I made was good for two significant figures and that was enough for the application.  With a little practice, one could move rapidly through the calculations.

The idea came along too late to catch on as we were busy converting from analog to digital in the early '70s.  And desktop programmable calculators were becoming available.

I still have my cardboard unit and it functions, but it isn't useful for anything today.

Best regards,

Maynard

Well most likely it is difficult to get into an market if nobody ever
saw something and it is or looks complicated.

But why wasn't the Gilson used at American universities, or was it? Was
it used by American engineers? How was it in price compared to a K&E
loglog or a Versalog?

Best regards

Andreas

Why was the two-cursor, one-disk format not more popular in Europe?

Why was the Pythagorean P scale not more popular in North America?

Good questions.  No idea.
--
John Runnels

Thanks, John,

I understood now the principle. When using normal dividers the change of
scale is not possible that easy, neither on linear nor on circular
sliderules, this only works with radial cursors that easy. Or on a
linear rule with such a special cursor with cursor on top of the cursor,
from which somebody once showed a picture. With normal dividers on a
radial rule the scale cannot be mixed up with another at all and on a
linear rule one must take care not to use diagonals...

Now what do you think are then the reasons that these dial rules weren't
more popular all over and even practically unknown in Germany and other
parts of Europe?

Best regards

Andreas

https://www.theguardian.com/technology/2021/sep/16/home-computing-pioneer-sir-clive-sinclair-dies-aged-81

.....But he did not make personal use of his own inventions. His daughter said he never had a pocket calculator as far as she knew, instead carrying a slide-rule around with him at all times. And he told interviewers he used neither a computer nor email....

This is a follow up on post-IM2021 questions about how to do chained calculations on a Gilson Slide Rule.  Here is a short video illustrating how one might do a longer chained calculation on a Gilson rule.  The bottom line is that, although the mechanics differ, the principles are just the same as on a slide rule with C and D scales:

https://youtu.be/PjdhZC91G-Y

For reasons I have not attempted to decipher, YouTube's processing rendered the video quality embarrassingly poor.  Lacking the time and inclination to try to figure out why, I have chosen to simply leave it as is, but to only make the video available for a few days.  It illustrates the principles involved well enough, even though it is fuzzy -- Please be charitable; the video is no masterpiece!  I do not intend to leave the video up on YouTube very long, so take a look at it in the next few days if you might be interested.
--
John Runnels

If a sliderule from 1947 has wooden pegs then I slowly think that they
took everything which earlier they sorted out and make something useful
out of it. M for "aus dem Müll" (out of garbage!-)

Andreas,

"you can try and use "Dr. Beckmann Fleckenteufel Stifte und Tinte" to remove the ink"

Available from Amazon.de for half the price of a cup of coffee.

Gabriel
P.S.: No, I don't work for Amazon and didn't get any money from them. :-D

Andreas,
you can try and use "Dr. Beckmann Fleckenteufel Stifte und Tinte" to remove the ink. I've done this several times on Nestler slide rules without causing any damage to paint which is used for the scale. Just pure on a casmetic tissue, gentle pressure and repeated for two, three times.
Kind regards,
Andreas
P.S.: No, I don't work for Dr. Beckmann and didn't get any money from them. !-)

Andreas and others,

Just to complete the picture, I have now found my beech wood Rietz and checked it over, taking into account all your observations.

Mine is also dated April 1947, but is labeled simply "1/87 Syst. Rietz" in the well. However, on the left hand end it is engraved/blind stamped with a letter M (as Andreas's example) which I had not noticed before.

Overall, the scales do not seem to have shrunk, although the two halves of the stock have shifted slightly, so that the A index no longer lines up with the D.

Unfortunately there is no cursor or box, so I can't help on that. Finally, as I think I mentioned previously, the celluloid scales are fixed with wooden pins/pegs.

I'm beginning to think the "M" might stand for mystery...

Alan