7 Matching Annotations
  1. Jan 2024
    1. 1956 --- The ST scale on rules that had Decimal Trig scales were converted to an SRT scale.
    2. 1956 0 88,500 88,500

      My 4181-3 slide rule was likely manufactured in 1956 as it has the SRT scale initiated in 1955 and has a serial number 004365 which is in the series 3 segment which reset in 1956 and ran from 0 to 88,500 that year.

      https://www.mccoys-kecatalogs.com/keserialnumbers/Dating-2.htm

    1. 1955b - The scale set was changed. ST scale was changed to SRT on the 4081s only.

      My 4181-3 was likely made in 1955 or after as it has the SRT and not the ST scale. (It has a 1947 copyright mark on it.)

    2. 1955b (4081-3, 4081-5, 4181-1, 4181-1C, E4181J, 4181-3, 68 1200, 68 1205, 68 1210, 68 1215, 68 1220, 68 1251, 68 1256, 68 1261, 68 1282, & 68 1287) Scale sets: Front: LL02 LL03 DF = CF CIF CI C = D LL3 LL2 Rear: LL01 L K A = B T SRT S = D DI LL1

      These are the scale sets on my K+E 4181-3 slide Rule

    1. 4181-3 10" Log Log Duplex Decitrig Plastic 4081-3 family

      The Keuffel & Esser 4181-3 was part of the 4081-3 family and was described in their catalogs as a 10 inch Log Log Duplex Decitrig Plastic slide rule.

      via https://www.mccoys-kecatalogs.com/KEModels/kexrefmain.htm