Keuffel & Esser Co. Slide Rules
 Updated RegularlyClick REFRESH on your browser if pages seem unchanged   Visit our amazing document server. Everything from SciFi to Ethics.Welcome To The Sphere Research Slide Rule Universe ! K+E, Slide Rules from one of America's premier manufacturers! | Sphere Research Corporation 3394 Sunnyside Rd. West Kelowna, BC, Canada V1Z 2V4 Phone: +1 (250) 769-1834 FAX:+1 (250) 769-4106 A great source for test equipment, repairs, calibrations, useful metrology information, and of course, SLIDE RULES! Just SCROLL DOWN to see everything! |
 K+E's 38th catalog frontpiece, CLICK for larger pic! |
 Mr. Wilhelm (William) Keuffel (left) and Mr. Hermann Esser (right), CLICK for larger pic! Archival photograph from recently discovered documents passed from K+E to Azon to Itellicoat at the dissolution of each company. From the 100th anniversary company memorial publication materials.   Visit Clark McCoy's K+E Catalog Site. |
K+E 100th Anniversary Publication (1967)
Thanks to Ray Brohinsky, here's the 100 year book files compressed and turned into a smaller (13mb) PDF document:
|
 Page 36, showing K+E's corporate timeline versus major world events. CLICK for full size JPG file. |
||
The day the slide rules arrived... CLICK to see the full sized image! |
slide rule designs... CLICK to see the full sized image! |
CLICK to Download Click to VISIT or RETURN Click Here  To go to the Slide Rule Marketplace |  |  An amazing tour with K+E from 1940.  Learn How to Operate a Slide Rule with a 1928 K+E Lesson |
Keuffel & Esser Co. factories were based in Hoboken, New Jersey (USA), with offices in New York, Chicago, St. Louis, San Francisco, Detroit, and Montreal. Started in 1867, slide rules were only a very small part of K+E's product offering, which included everything from drafting paper to survey instruments and drafting aids. K+E held patents for a wide range of slide rule features, including improved cursor indicators, functions and scales, and the adjustable body mechanism. Caught by the huge market shift created by electronic calculators, CAD systems and laser surveying systems, which displaced all of their strong markets, K+E shrank dramatically after 1972. Slide rules were never very profitable for K+E, and production and most inventory was gone by the mid-70's. K+E even sold some TI manufactured calculators for a brief period trying to capitalize on their existing customer base and industry knowledge. The final assets of K+E, mainly involving paper products, were sold to AZON in 1987, after several painful internal re-organizations. AZON also acquired the remaining assets of Hughes-Owens in 1988, and the POST Company in 1994, relating to it's principal business, which is drafting and reproduction paper and film. Only these paper products survived the shakeout in all these related businesses. Dietzgen still exists today, but like AZON, is mainly in the paper business, and itself was taken over by Intellicoat. Most K+E slide rules were originally implemented in mahogany, with celluloid white scale overlays, engraved scales and glass cursors. People (especially on eBay) often mistakenly think the scales on older K+E rules are made of Ivory, but they are not, they are made of white celluloid. Later slide rules like the 4097 were made from Xylonite, and then (4181, Deci-lon and Doric series) from "Ivorite", a smooth, white, long wearing plastic (Cycolac/ABS). Xylonite was quite brittle, and not an ideal body material, Ivorite was much better, more rugged, whiter in color, and has very good sliding/lubricating properties. K+E rule scales were normally engraved (sorry, "engine divided") for long wearing life, and often filled in different colors to accent inverse scales. A few inexpensive rules like the plain wood body 4058, have an impressed/printed scale. Glass magnifying cursor indicators were available, and increased the settability and resolution of virtually any rule, often making a 10" rule the effective equivalent of a 20" version. Reference data for the K+E magnifiers is shown towards the end of the table. Notes: It is somewhat unclear what the difference is between K+E slide rule numbers that have an "N" at the front, and those that do not. Catalogs do not clarify this, but according to Ed Chamberlain, it reflects subtle design differences in a scale or mechanical construction detail, with the N designation being the NEW version of the rule. This is only a partial clue, as many K+E rules, such as the venerable 4053 Mannheim rule, existed in many subtle variations of body, cursor and scale designs, but were not differentiated by any part number change (a highly confusing situation). This rule and many others were then finally re-named with a 68-series number confusing matters even worse for collectors. Note that PIckett (a competitor) also added N to the front of rule numbers to indcate new physical designs.  4081-3Log Log Duplex Deci-Trig 68-1100 Deci-Lon 4053-3 Polyphase 4088-3 Duplex Polyphase "4000" series data here is from the 1936 K+E catalog and some later numbers from live examples, later "4100" series numbers and 68-rules are taken from live examples and a 1964 K+E brochure. The dash number on these "4000" series rules indicates the size of the rule (based on the same scale pattern), and is the SCALE LENGTH, not the over-all size of the rule itself. There was a brief period (50's) where K+E used a different numbering scheme beginning 90 (9081 for example) for DORIC brand Ivorite body rules but then changed back to 4100 series numbers. 68-rules have no dash to indicate length, but had different ordering part numbers for different cases (with or without pocket clip or other case styles), although the slide rule number itself was not changed, raising confusion to new levels for all involved. Dating K+E slide rules is a complicated task, as serial numbers were recycled three times at K+E. Based on external clues from the body and cursor (although caution is needed there, as it may have been replaced), as well as case and manual details, and any copyright or patent dates, it is possible to place the rule within one of the three probable cycles. The copyright or patent date IS NOT the date of manufacture, and may be decades earlier than the real production date. Note that evidence from Deci-lon rules shows at least one additional cycle after the ones shown below, plus some random numbers after 1964. Considerable work was done to calculate these serial number cycles by Wayne Feely and Ed Chamberlain, and Ed's quick chart is provided here with permission to help you date your rules. Click on the chart to bring up a larger version! Note that Joe Soper identified many end of manufacture rules that had out of sequence parts, so rules made in the last year or so of production may have numbers that do not fit this chart. Click for bigger Chart!
|
RETURN
Walter Shawlee 2.
