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.
Am 19.09.2021 um 20:51 schrieb meine:
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
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
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
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
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
* 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).
Prof. Dr. -Ing.