Engineering Slide Rules
Collection of engineering slide rules from the 1970's

I used these calculators as a young mechanical engineer in the 1970's and 80's before the PC came into being.

Some of the cardboard slide rules were used in the 60's when I was studying engineering.

Mear's calculators:
These are all in excellent condition, no marks (apart from my name inscribed in neat lettering)

They are beautifully constructed (from the catalogue description):

"Mear calculators are of the highest quality, precision made from non-warping white and clear acrylic, with main dials 3mm thick and subsidiary dials 1.5mm thick. All scales and lettering are clearly and sharply engraved, not printed, and are filled in multi-colours to facilitate use."
Pipe Flow Calculator for liquids and Gases (Turbulent Flow)
Metric, with instruction book and plastic protection sleeve
Domestic Heating calculator (for Houses and Bungalows)
Metric, with instruction book and plastic protection sleeve
Steam Flow Calculator for flow at pressure or vacuum
Metric, with instruction book and plastic protection sleeve
Weight Calculator for rolled steel sections
Metric, with instruction book and plastic protection sleeve
The cardboard rules were generally free-issue from various manufacturing companies to promote their products. Nevertheless, they were very good tools.

Keystone Valve sizing Rule (Imperial, cardboard)
McPherson's Steel plates Squares, Sheets and Flats (Imperial, cardboard)
Rheem Metric pipe size and flow rate selector  (Metric, cardboard)
Torque Calculator - calculates torque, horsepower, loads (Imperial, cardboard)
SAA Conversion Slide (Metric to Imperial to Metric) (Plastic and cardboard)