Jim Cerny's Table of Machine-Time Rules at the
2004 East Coast Oughtred Society Meeting.
November 6, 2004.  Report and images by Jim Cerny.  (3/2005).

I decided to focus my display table on sixteen machine-time rules, presented here as scanned images rather than photographs. Machine-time rules are used to calculate time to do machining operations, often with use of a lathe. The kinds of rules are very diverse and I've made a somewhat aribtrary distinction here between those that are without a cursor and more like slide charts (eponymously "Perrygrafs"), versus those those with a cursor and in the form of traditional slide rules.

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This display is a first step in the process of writing an article on machine-time rules for the Journal of the Oughtred Society. If you have any unusual machine-time rules, please write to me!

Jim's Table of Machine-Time Rules:  Slide Rules
Image Thumbnails Description

AWF Sonderrechenstab SR 701 Slide Rule
AWF Maschinenzeit. Two slides. Cursor is missing. AWF is now IWA and this rule is equivalent to the IWA 701. Instructions on back in German.

216mm x 45mm overall
for F. Bahlecke
cardboard with celluloid shell.

Dietzgen 1751 Slide Rule
Labeled as the "Maniphase Multiplex - Industrial Type," this rule combines machine-times scales on the front with common mathematical scales on the back.

The model 1751 rule manifests the proposed Dietzgen "Langsner" 1770-T rule. The Langsner is illustrated in Calvin Bishop's book and was patented (1,894,294), leading many to believe it was manufactured. No examples are known. Meanwhile, the scales on the front of the 1751 match the machine-time scales described in the patent.

317mm x 33mm overall
celluloid on mahogany.

Faber-Castell 111/48 Maschinenzeit
Scales based on System Dr. Winkel. In German (have not seen other language versions). This also exists in a 1/48 model with celluloid on wood.

300mm x 50mm overall

Fearns no. 2 Lathework Slide Rule
Fearns no. 2 Lathework Machining Time Calculator. See sample calculation from manual.

192mm diameter

IWA 01206 Prof. Olsen Slide Rule
IWA 01206 roughness slide rule for turning. Measurement scales on top and bottom edges are clear. Copyright by Prof. K. V. Olsen. Instructions on back in English and German.

280mm x 50mm overall

Lawrence 10-G Slide Rule
Cutting speed calculator made for Donald Roberton & Company.

264mm x 28mm overall
Lawrence Engineering
wood (pine?).

Nestler Mecanica 0260
Italian version (most often seen), also exists in a German version.

295mm x 38mm overall
n.d. (late production)
celluloid on mahogany.

Jim's Table of Machine-Time Rules:  Slide Charts
Image Thumbnails Description

Adamas Slide Chart
Adamas Carbide Corporation slide chart for feed, speed, and horsepower calculations.

184mm x 70mm overall
Perrygraf Corp.

Cincinnati Milling Machine Slide Chart
Cincinatti Milling Machine cutting speed and milling setup calculator. Unusual double-circle design.

200mm x 125mm overall
Perrygraf Corp.

Gisholt Time Computer (Metal)
All metal, with a very unusual nested slide within a slide design. Covered by a 1922 patent. Overall construction and finish identical to the Richardson rules of the same era.

276mm x 43mm overall
1922 patent
enamel on metal.

Gisholt Time Computer (Plastic)
A complete redesign of the earlier all-metal rule.

255mm x 60mm overall
Graphic Calculator Co.

Illinois Drilling Slide Chart
Illinois Tool and Instrument drilling computer, selecting drill bits for speed and feed rates.

214mm x 108mm overall

Illinois Hobbing Slide Chart
Illinois Tool and Instrument hobbing computer, selecting speed and feed rates for particular gears.

214mm x 108mm overall

Lees-Bradner Hobbing Slide Chart
Lees-Bradner Hobbing Time Calculator. Two slides.

212mm x 80mm overall
Perrygraf Corp.

Republic Steel Slide Chart
Republic Steel Corporation speed and feed rate calculator for Enduro stainless steel bars.

184mm diameter
Perrygraf Corp.
part 466A 9600 I-48.

Wendt-Sonis Slide Chart
Wendt-Sonis slide chart (calculator) for computing the feed and speed of material with carbide tipped tools.

179mm x 80mm overall
Perry Graf Corp.

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