View source for A.W. Faber-Castell 67

The '''67''' pattern slide rule family by A.W. Faber-Castell is a series of pocket size slide rules starting in the fifties.  It contains several variations of layout including revisions over time.

{{Infobox calculator|name=67/54 Darmstadt|type=Slide Rule (Pocket)|manufacturer=A.W. Faber-Castell|introduced=C. 1955|successor=67/54 B Darmstadt|precision=2 to 3 Significant Digits|display_type=Analogue Scales, Sliding Cursor (multiple hairlines)|display_size=5" (pocket)|dimensions=15 cm (approx. 6")}}{{Infobox calculator|name=67/87 Rietz|manufacturer=A.W. Faber-Castell|introduced=C. 1955|successor=67/87 b Rietz|precision=2 to 3 Significant Digits|display_type=Analogue Scales, Sliding Cursor (multiple hairlines)|display_size=5" (pocket)|dimensions=15 cm (approx. 6")}}

== Overview ==
The 67 pattern of slide rule is a line of simplex rules in several layouts.  They are characterized by being made of "Geroplast" plastic, with scales engraved into the plastic.  Most sported scale extensions on the C and D scales, with many having extensions on the A and B scales as well.  Most members also sported multiple hairlines on their cursor, which facilitated quick calculations and single-setting options for common operations.

=== R Model Variants ===
For most of the available models, the blank space on the back gave enough room to fit a six digit Addiator adding machine, along with various references and conversions.  For all models with an R variant available, the  adjustments to the layout will be described.

== 67/54 Darmstadt ==
The model 54 Darmstadt was a pocket version of the highly popular Darmstadt layout.  It sported a cursor with at least two secondary hairlines which helped with finding the area of circles with known diameter, among other things. Faber-Castell marketed this model towards physicists, engineers, mathematicians, and university students.

=== Layout ===
the model 54 was an archetypal Darmstadt layout, typical of most simplex slide rules with this designation.  Notable in this layout are the inclusion of a P scale and a lack of an ST scale, as well as the inclusion of LL scales, which is unusual for a simplex rule.

==== Front ====
in. L K A (B CI C) D P S T

==== Back ====
(LL<sub>1</sub> LL<sub>2</sub> LL<sub>3</sub>)

Note that this is a simplex rule.  All scales on the back are used by inverting the slide, which limits some operations.  The later 54 B model added windows to the back which allowed for use without inverting the slide.

==== R Model ====
the 67/54 R Darmstadt made no layout changes for accommodating the Addiator on the back. The RB model had no rear window for LL scale use without inverting the slide.

== 67/87 Rietz ==
The model 87 Rietz was consistent with layouts seen more typically in the US.