Relay, Ricoh, San-ai group Includes Exported and Re-Branded U.S. Models Relay slide rules were manufactured in post-war Japan, originally branded NIKKEI, by Nippon (Japan) Slide Rule Company which was founded c1950. The company then became San-Ai Kekki Ltd. exporting slide rules to the USA as Relay Industrial Company. In April of 1963, the San-ai Group joined with Riken Optical Co. which was founded by Kiyoshi Ichimura in 1938 as Riken Kankoshi Co., Ltd which manufactured sensitized paper. This was later to become Ricoh Ltd, a Japanese conglomerate of companies. Ricoh supplied Ricoh brand slide rules to the United States (Ricoh Industries, USA) and to European (Ricoh Europe SA in Switzerland) markets and re-branded slide rules to other companies such as: Alvin, Charvoz-Roos, Compass, Dietzgen, Eagle, Engineers, Jason, Lafayette, Lietz, Tobe, Lutz, Fuji, Micronta, Omega, Paleo, Pickett (the B1 only), Relay, Ricoh, Sans & Streiffe, SIC (Scientific Instruments Co), Skyline, SELSI, Staedtler-Mars, J.C.Penny, and Wallace & Wallace.

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AA

ISRM AA SR815

AA SR815 Made in Japan by Relay for AA, dc JK-4 (1961). Same as Relay 150 Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA

Alvin

ISRM Alvin 222P X-Act	Alvin 222P X-Act Made by Denmark - Similar to UTO models Front Scale 5.5in // K, A[ B, CI, C ] D, L Back Scale: [ S, ST, T ] Donated by david Hecht, Alexandria, VA
S571 Alvin 1150 Elite Decilog	Alvin 1150 Elite Decilog Made in Japan by Relay (RS-6) for Alvin Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, ST, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Multilined Cursor: Kw, HP, etc.

Compass
Compass Instrument and Optical Company
268 Fourth Ave. New York 10, New York

This specimen is not from Ricoh but it is here because this is the only other slide rule that was OEM'd and sold by Compass Instruments. ISRM Compass Midget (Gilson - 1931, 1936 Copyrights)	Compass Midget (Gilson - 1931, 1936 Copyrights) - 10.2cm dia Made in USA for Compass by Gilson Slide Rule Co., Stuart, Florida Front Scales C,CI,A,K,Log,LL1,LL2,LL3,LL4, Back Scales Binary, Fraction,Drill,Thread, Millimeter Donated by David Viscusi, Carlsbad, California David bought this slide rule when he was a Drafting apprentice at General Electric, Schenectady NY (1971). Already well used, it was purchased for $5 from a retiring engineer that helped design Large Steam Turbine Generators. It helped get him through his BSME night courses. David is now the Engineering & Technical Services Supervisor at Gemological Institute of America (GIA)
REF Compass 403 (c1962)	Compass 403 Made in Japan by Relay/Ricoh Front Scale 10cm // A [ B, CI, C ] D || 5in Back scale: [S, L, T ] Back: Calculating Guide formulas Scan provided by CassouOlivierCollection
ISRM Compass 505 (1962)	Compass 505 (Date Code K.K-4) Made in Japan by Relay/Ricoh Front Scale 13cm // A [ B, CI, C ] D, K || 5in Back scale: [S, L, T ] Back: Calculating Guide formulas Donated by David Hecht, Alexandria, Virginia
ISRM Compass 1018	Compass 1018 Made in USA - NY - by Bruning Front Scale 12.5cm // A [ B, CI, C ] D, K \\ 5in Back Scale: [S, L, T ] Back: Blank Originally Owned by W. Hatch (marking on sleeve) Donated by David Hecht, Alexandria, Virginia
S506 Compass 1315	Compass 1315 Made in Japan by Relay/Ricoh Front Scale A [ B, CI, C ] D, K Back Scale: [S, L, T ] Back: Equivalents
S231 Compass 1321 Log Log	Compass 1321 Log Log Made in Japan (FK1) for Compass Instruments Front Scale LL0, LL00, A [ B, K, CI C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2
S231 Compass 1321 Log Log	Compass 1321 Log Log Made in Japan (PS-4) for Compass Instruments Front Scale LL0, LL00, A [ B, K, CI C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA

Engineers

ISRM Engineers No.1050	Engineers No.1050 - Open Duplex Made in Japan by Relay - code KK-4 (1960) Front Scale 25cm // K, A, [ B, CI, C ] D, L || 10in Back Scale Equivalents [ S, S&T, T ] Donated by David Hecht, Alexandria, VA
ISRM Engineers No.1500 Duplex Decitrig Log/Log	Engineers No.1500 Duplex Decitrig Log/Log Made in Japan by Relay, dcLS-4 (1963), 21 scales, same a Relay 150 Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
P099 Engineers No.5500	Engineers No.5500 - Open Duplex Made in Japan - code KK-4 Front Scale A, [ B, S, T, C ] D, K Back Scale DF [ CF, CI, C ] D, L

Jason

S472 Jason 800	Jason 800 Made in Japan for Jason by Relay/Ricoh Front Scale A [ B, CI, C ] D, K Back Scale [ S, L, T ] Back: Equivalents
ISRM Jason 802 Decitrig Log/Log	Jason 802 Decitrig Log/Log Made in Japan by Relay, LS-4 (1963), 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
REF Jason 803 Log Log Duplex Deci-Trig	Jason 803 Log Log Duplex Deci-Trig Made in Japan by Relay/Ricoh 28 scales - c1965 Front Scale (extended) LL/0, L, K, A [ B, S Cos, ST Cos, T Cot, C ] D, DI, P, LL0 Back Scale (extended) LL/1, LL/2, LL/3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 Scan provided by Mark Armbrust, Boulder, Colorado website:marksmath.com

1960 Catalog, Slide Rule Page

Founded 1920 as Wholesale Radio Service Co. Inc. Trade names LaFayette, Trutest.The company sold radio sets, amateur radio equipment, citizen's band (CB) radios, and other communications equipment, as well as electronic components and even tools, through retail outlets as well as by mail-order.

ISRM Lafayette F341 Duplex Log Log Decitrig	Lafayette F341 Duplex Log Log Decitrig Made in Japan by Relay/Ricoh 21 scales (same as Ricoh 150) Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Original owner, marked on SR: T. Zidank Dept 72 Donated by David Hecht, Alexandria, VA
ISRM Lafayette F341 Duplex Log Log Trig	Lafayette F341 Duplex Log Log Trig Made in Japan by Relay/Ricoh - date code I.K-3 (1960) Front Scale (Trig scales:Deg-Min-Sec) LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Original owner, marked on case: Wayne Evans Donated by Ed Millis,Dallas, TX Note: A very astute collector had found this F341 and wrote ISRM saying that the description was wrong because the trig scales were in degree, minutes and seconds, rather than decimal degrees found on decitrig models. See the Lafayette F341 above. As it turns out we were both correct and Lafayette (or Ricoh) changed the scales set and ket the model number. Ed donated it to ISRM for others to enjoy.
S025 Lafayette F-381	Lafayette F-381 - Closed simplex OEM Japan for U.S. company Radio Shack Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Conversion Chart
C32 Lafayette F-382 (Concise 270)	Lafayette F-382 (Concise 270) Made in Japan by Concise - 11.2cm Dia Front Scale L, D ( C, CI, A, K ) Back Scale DI, D ( S, T1, T2, ST )
REF Lafayette F-428 Log Log Duplex Deci-Trig	Lafayette F-428 Log Log Duplex Deci-Trig Made in Japan by Relay/Ricoh 25 scales - dc I.S-4 (1960) Front Scale (extended) LL/0, L, K, A [ B, S, ST, T, C ] D, DI, P, LL0 Back Scale (extended) LL/1, LL/2, LL/3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 Scan provided by Mark Armbrust, Boulder, Colorado website:marksmath.com
P162 Lafayette F-681 Decilog	Lafayette F-681 Duplex Decilog  dc J.K-1 1961 OEM Japan Ricoh  for U.S. Company Lafayette - 24 scales Front Scale LL-0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1
REF Lafayette F-686 Vector log	Lafayette F-686 Vector log OEM Japan Relay/Ricoh for U.S. Company Lafayette - 26 scales Front Scale Tr1. Tr2, P', P L, K, A [ B, S Cos, ST Sr, Se, C ] D, LL03, LL02, LL01 Back Scale Sh1, Sh2, DF, A [ B, CF,CF, Th CI, C, LL1' ] D, LL3, LL2, db, Archive - Scan courtesy of Rod Lovette Collection (UK) Note the short, unique LL1' scale which was developed in the Lafayette laboratory to provide more accuracy when calculating logeN and ex when x is close to 1. Instructions 396KB PDF
P220 Lafayette 99-7030	Lafayette 99-7030 OEM Japan Relay/Ricoh  for U.S. Company Lafayette - 9 scales Front Scale 13cm // A [ B, CI, C ] D, K || 5in Back Scale: [ S, L, T ] Back: Quick Computing aids
ISRM Lafayette_99-70302 (1972)	Lafayette_99-70302 (Date Code US-3) Made in Japan by Relay/Ricoh (same as Ricoh 505) Front Scale 13cm // A [ B, CI, C ] D, K || 5in Back scale: [S, L, T ] Back: Calculating Guide formulas Donated by David Hecht, Alexandria, Virginia
ISRM Lafayette 99-7031 Duplex Decitrig Log/Log	Lafayette 99-7031 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh NS-2 (1965), 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
ISRM Lafayette 99-70310 Duplex Decitrig Log/Log	Lafayette 99-70310 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh NS-2 (1965), 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
P179 Lafayette 99-7099 Decimalog	Lafayette 99-7099 Decima-log 1961 OEM Japan Relay/Ricoh  for U.S. Company Lafayette - 24 scales Front Scale LL-0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1
P180 Lafayette 99-7099 Decima-log	Lafayette 99-7099 Decima-log 1961 OEM Japan Relay/Ricoh  for U.S. Company Lafayette - 24 scales Front Scale LL/0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL/1, LL/2, LL/3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1
ISRM Lafayette 99-70559 Decima-log (1968)	Lafayette 99-70559 Decima-log - date code Q.S-3 OEM Japan Relay/Ricoh (QS-3) for U.S. Company Lafayette - 28 scales Front Scale (extended) LL/0, L, K, A [ B, S Cos, ST ST, T Cot, C ] D, DI, P, LL0 Back Scale (extended) LL/1, LL/2, LL/3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 Donated by Russell Fox, Anchorage, Alaska. This slide rule was used by his father. He worked as an Electrical Engineer with BPA in Portland, Oregon. BPA and ASEA had a joint venture in providing electrical energy.
REF Lafayette 99-7102 Vector log	Lafayette 99-7102 Vector Log (Same as F-686) OEM Japan Relay/Ricoh for U.S. Company Lafayette - 27 scales Front Scale Tr1. Tr2, P', P L, K, A [ B, S Cos, ST Sr, Se, C ] D, LL03, LL02, LL01 Back Scale Sh1, Sh2, DF, A [ B, CF,CF, Th CI, C, LL1' ] D, LL3, LL2, db, Archive - Tom Dilatush Collection Note the short, unique LL1' scale which was developed in the Lafayette laboratory to provide more accuracy when calculating logeN and ex when x is close to 1. Instructions 396KB PDF
REF Lafayette 99-71029 Vector log (1961)	Lafayette 99-71029 Vector log - Date Code J.K-1 OEM Japan Relay/Ricoh for U.S. Company Lafayette - 26 scales Front Scale Tr1. Tr2, P', P [ Q, ST Sr, Se, C ] D, LL03, LL02, LL01 Back Scale Sh1, Sh2, DF, A [ B, CF, Th CI, C ] D, LL3, LL2, db, Archive - Scan courtesy of Rod Lovette Collection (UK) Note the short, unique LL1' scale on the C scale which was developed in the Lafayette laboratory to provide more accuracy when calculating logeN and ex when x is close to 1.
REF Lafayette 99-7128 Decimadyne	Lafayette 99-7128 Decimadyne OEM Japan Relay/Ricoh for U.S. Company Lafayette - 24 scales Front Scale db -20-0 +0-20, DF [ CF, CIF, CI, C ] D, A Back Scale XC, XL, K [K1, S, T ] F2, F1, DI, Archive - David Hecht collection

Lutz

S188 Lutz 102SC	Lutz 102SC - Duplex Made in Japan Front Scale S, K, A [ B, CI, C ] D, L, T Back: Blank
ISRM Lutz 252 U.S. dcMS-4 (1964) Expanded Family Biography of Wallace and Ruth Kane and daughter Ann Kilby (7.09MB) See other slide rules from this talented family in the K&E, Post and Pickett Galleries.	Lutz 252 U.S. dcMS-4 (1964) Made in Japan - Marked as U.S. (note red Cos, T, and Cot scales) Front Scale K, A [ B, T1 Cot1, T2 Cot2, ST ST, S Cos, ] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L Owned by Ruth Moira (Kilby) Kane (1921-2007). Donated in her memory by her daughter Anne Kilby, Kingston, Washington Ruth Moira Kane (1950) with daughter Anne Kilby Ruth was born in Seattle Washington, a child of academic tutors. The family moved to be part of the University of Denver. She acquired her first slide rule in high school and used it in physics while working as an assistant to Dr. Recht on the DU observatory. She went to UC Berkely, received her Masters and worked on her PhD. She was hired to work at the defense Laboratory at Livermore where she met her second husband, Wallace E. Kane (see the K&E gallery for his slide rule). After 1971 she did scientific editing and translated German articles. The couple relocated to the Puget Sound area in 1973 and Ruth became a public organizer to protect the local forests from over-development. She was an active musician, like her husband.
Lutz 252 U.S. Government (1963) ISRM 12.06.04.06	Lutz 252 U.S. Government date code L.S.-1 (1963) Made in Japan - Marked as U.S. Government Front Scale K, A [ B, T1, T2, ST, S] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L Donated by Stephanie H., Phoenix, Arizona - representing the Huang Collection, San Diego, California The collector, who prefers to remain anonymous, obtained a B.S. degree in Physics from Taiwan's National Tsing Hua University in 1971. His love for computation has encouraged him to build a collection of slide rules, HP and TI calculators, as well as abaci, many displayed at ISRM.
ISRM Lutz 252 U.S.	Lutz 252 U.S. Made in Japan - Marked as U.S. (note red Cos, T, and Cot scales) Front Scale K, A [ B, T1 Cot1, , T2 Cot2, ST ST, , S Cos, ] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L Donated by David Hecht, Alexandria, VA

Micronta

ISRM Micronta (Nestler) 14/52	Micronta (Nestler) 14/52 Made in Germany by Nestler for US Brand Micronta Note: All other Microntas were made by Ricoh Front Scale 10.5in // A [ B, C ] D Back Scale [ S, lg, T ] Multilined cursor Back: Equivalents (in English) Donated by David Hecht, Alexandria, Virginia
S306 Micronta 150 Duplex Decitrig Log/Log	Micronta 150 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh J.K-3- 21 scales dc J.K-3 (1961) Front Scale (Trig scales:Deg-Min-Sec) LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2
ISRM Micronta 157 Electrical Duplex Vectorlog	Micronta 157 Electrical Duplex Vectorlog Made in Japan by Keikico San-ai (Ricoh) dc J.K-4 (1961) Front Scale Sr, SΘ, P', P [ Q, CF, CI, C ] D, DF, LL2, LL3 Back Scale Sh2, Sh1, A [ B, K, Th, C ] D, Tr1, Tr2, db Donated by David Hecht, Alexandria, VA
ISRM Compass 505 (1959)	Compass 505 (Date Code H.K-2) Made in Japan by Relay/Ricoh Front Scale 13cm // A [ B, CI, C ] D, K || 5in Back scale: [S, L, T ] Back: Calculating Guide formulas Donated by David Hecht, Alexandria, Virginia
P054 Micronta 551 Duplex Log/Log	Micronta 551 Duplex Log/Log Made in Japan - 24 scales Front Scale LL-0, L, K, A [ B, T, S, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1

Nikkei

REF Nikkei No 150

Nikkei No 150 Made in Japan by Relay - Nikkei was the parent Company Front Scale LL/1, LL/2, LL/3, A [ B, T Cot, S Cos, ST Cos, K, CI, C ] D, S, ST, T Back Scale L, K, DF [ CF, CIF, CI, C ] D, LL0, LL/0 Scan provided by Cory Fletcher

Olson

S380 Olson TL-373 (Relay 150)	Olson TL-373 (Relay 150) Made in Japan by Relay for Olson (electronic supply), Akron, Ohio. Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2
ISRM Olson TL-373 (Relay 150)	Olson TL-373 (Relay 150) dc JK-4 (1961) Made in Japan by Relay for Olson (electronic supply), Akron, Ohio. Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
Olson TL-472 Electrical	Olson TL-472 Electrical dc N.S-3 (1965 Shizuoka Factory) Made in Japan by Relay/Ricoh for Olson (electronic supply), Akron, Ohio. Front Scale 25cm // E, Dynamo/motor, Volt, V, A(kw) [ B(hp), K, CI, C ] D, S, T || 10 in Back Scale [ LL3, LL2, LL1, L ] Instructions 4.3MB PDF

Omega

S019 Omega DT-1015

Omega DT-1015 Duplex Made in Japan by Relay/Ricoh for Omega Front Scale K, A [ B, S, ST, T, C ] D, D1 Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL2, LL3

REF - Pickett B-1

Pickett B-1 - Duplex - ca.1950 Made in Japan by Ricoh - The only Laminated Bamboo Pickett model  Front Scale LL0, L, A [ B, Cos S, SecT ST, T T, C ] D, sqr1, sqr2, LL0 Back - Slider LL1, LL2, LL3, DF [ CF, CIF, CI, C] D, LL3, LL2, LL1 Archive

Relay

REF Relay 5 inch	Relay 5 inch - Closed simplex Made in Japan Front Scale A [ B, C ] D, K Back: Blank
S026 Relay 82	Relay 82 - Closed simplex Made in Japan Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Blank
S027 Relay 83	Relay 83 - Closed simplex Made in Japan Front Scale K, DF [ CF, CI, C ] D, A Back Slider [ S, L, T ] Back: blank
S171 Relay 102	Relay 102 - Closed simplex Made in Japan by Keikico Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Conversion Chart
REF Ricoh 107 Electro	Ricoh 107 Electro - Closed simplex Made in Japan by Ricoh, dc G.K-2 (1958) Front Scale 25cm // Dynamo, MotorLL1, A(KW) [ B(HP), CI, C ] D, LL2, Volt || 10in Back Scale Equivalents [ S, L, T ] Scan by Olivier Cassou, France
ISRM Relay 150 Log-Log Decitrig	Relay 150 Log-Log Decitrig Made in Japan by Relay dc B.K-4 (1951) Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
ISRM Relay 153 Decitrig	Relay 153 Decitrig Made in Japan by Relay dc HS-2 (1957) for S.I.C. (Scientific Intruments Inc) in Berkely, CA Front Scale K, A [ B, S, ST, T C ] D, DI Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
REF Relay 157 (Electrical)	Relay 157 - (Electrical) Duplex Made in Japan by Keikico (Ricoh) Front Scale Sr, SΘ, P', P [ Q, CF, CI, C ] D, DF, LL2, LL3 Back Scale Sh2, Sh1, A [ B, K, Th, C ] D, Tr1, Tr2, db Archive - Atsushi Tomozawa collection (Japan)
REF Relay 158 (Electrical)	Relay 158 - (Electrical) Duplex Made in Japan by Keikico (Ricoh) Front Scale Sh2, Sh1, Th, A [ BI, S, T, CI, C ] D, LL3, LL2, LL1 Back Scale X2, X1, P2, P1 [ Q, Y, L, LX, I ] I, LΘ1, LΘ2, LY Archive - Atsushi Tomozawa collection (Japan)
ISRM Relay 252	ISRM Relay 252 dc K.K-4 (1962) Made in Japan by Ricoh Front Scale K, A [ B, T1, T2, ST, S] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L
P134 Relay T-501	Relay T-501 - Closed simplex Made in Japan Front Scale 13cm // A, [ B, CI, C ] D, K || 5in Back Slider [ S1, L, T1 ] Back: Conversion Chart
P135 Relay 505	Relay 505 - Closed simplex Made in Japan Front Scale 13cm // A [ B, CI, C ] D, K || 5in Back Slider [ S, L, T ] Back: Conversion Chart
REF Relay B-506	Relay B-506 - Closed simplex Made in Japan Front Scale 13cm // DF [ CF, CI, C ] D, A || 5in Back Slider [ S1, L, T1 ] Back: Conversion Chart Scan by Olivier Cassou, France
ISRM Relay 550	Relay 550 - Open Duplex Made in Japan by Relay - code BS-2 (1951) Front Scale A [ B, S1, T1, C ] D, L Back Scale DF [ CF, CI, C ] D, K Donated by David Hecht, Alexandria, VA
ISRM Relay 602 (c1952)	Lafayette_99-7032 (No Date Code) Made in Japan by Relay/Ricoh (6 inch) Front Scale 15cm // K, A [ B, CI, C ] D, L || 6in Back scale: [S, L, T ] Back: Calculating Guide formulas Donated by David Hecht, Alexandria, Virginia
REF Relay 605 Electro	Relay 605 Electro Made in Japan Front Scale 15cm // Dynamo-Mot, L1, A [ B, CI, C ] D, L2, Volts || 6in Back Scale: [ S, L, T ] Back: Equivalents Table Archive - Atsushi Tomozawa collection (Japan)
ISRM Relay DT-1015 Trig	Relay DT-1015 Trig Made in Japan by Relaybr> Front Scale K, A [ B, S, ST, T C ] D, DI Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
ISRM Relay T-1031	Relay T-1031 Made in Japan by Relay - code KK-4 (1960) Front Scale 25cm // K, A, [ B, CI, C ] D, L || 10in Back Scale Equivalents [ T2, T1, ST, S ] Note: metal bridge (spring) on back is very corroded Donated by David Hecht, Alexandria, VA

Ricoh

ISRM Ricoh 82 (8 inch version of 102)	Ricoh 82 - Closed simplex Made in Japan by Ricoh, dc US-5 (1972) Front Scale A [ B, CI, C ] D, K Back Slider Equivalents [ S, L, T ] Donated by David Hecht, Alexandria, VA
ISRM Ricoh 102 (10 inch version of 82)	Ricoh 82 - Closed simplex Made in Japan by Ricoh, dc US-5 (1972) Front Scale A [ B, CI, C ] D, K Back Slider Equivalents [ S, L, T ] Donated by David Hecht, Alexandria, VA
S091 Ricoh 107 Electro	Ricoh 107 Electro - Closed simplex Made in Japan Front Scale E (Dynamo), V (volt), A (amp)[ B, K, CI, C ] D, S, T Back Slider [ LL3, LL2, LL1, L] Back: Conversion Chart
REF Ricoh 116	Ricoh 116 - Closed simplex Made in Japan by Ricoh Front Scale 25cm // K, DF [ CF, CIF, CI, C ] D, A, DI || 10in Back Scale Equivalents [ T1, T2, L, S ] Scan by Olivier Cassou, France
REF Ricoh 121 Log-Log	Ricoh 121 Log-Log - Closed simplex Made in Japan by Ricoh Front Scale 10in // S, T, A [ B, K, CI, C ] D, P || 25cm Back Scale Equivalents [ L, LL1, LL2, LL3 ] Scan by Olivier Cassou, France
S333 Ricoh 150 Duplex Decitrig Log/Log	Ricoh 150 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh RS-3, 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2
ISRM Ricoh 153 Trig	Ricoh 153 Trig Made in Japan by Ricoh dc LS-2 (1961) Front Scale K, A [ B, S, ST, T C ] D, DI Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA
ISRM Ricoh 252	Ricoh 252 Made in Japan by Ricoh Front Scale K, A [ B, T1 Cot1, , T2 Cot2, ST ST, , S Cos, ] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L Donated by David Hecht, Alexandria, VA
P082 Ricoh 403 4inch	Ricoh 403 - Closed simplex Made in Japan - in Retail Box Front Scale 10cm // A, [ B, CI, C ] D, S, T Back Slider [ S, L, T] Back: Conversion Chart
P105 Ricoh 550	Ricoh 550 - Open Duplex Made in Japan by Relay - code NK-2 Front Scale A, [ B, S, T, C ] D, K Back Scale DF [ CF, CI, C ] D, L

Sans & Streiffe

S245 Sans & Streiffe_310	Sans & Streiffe 310 Made in Japan by Relay dc G.K-3 (1958) for Sans & Streiffe Front Scale (extended) 25cm // K, A [ B, CI, C ] D, L || 10inch Back Scale [ S, S&T, T ]
Sans & Streiffe No. 311 Log Log ISRM 12.09.25.02	Sans & Streiffe No. 311 Log Log Made in Japan by Relay dc P.S-2 (1967) for Sans & Streiffe Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, ST, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Original owner (Name marked inside flap and initials on stock): H. Mayer
S320 Sans & Streiffe 312	Sans & Streiffe 312 Made in Japan by Relay dc J.S-3 (1961) for Sans & Streiffe Front Scale LL0, L, A [ B, S, ST, T, C ] D, DI, P, LL0 Back Scale LL1, LL2, LL3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1

S.I.C.
These Ricoh manufactured Slide Rules have a large number of models so they have their own Sci.Inst.Co. SIC gallery

SKYLINE Distributors Denver, Colorado

Skyline Technolog 151 ISRM 06.12.20.01

Skyline Technolog 151 Made in Japan by Relay for Skyline Distributors dc P.S-4 (1967) Front Scale (extended) LL-0, L, K, A [ B, S Cos, ST ST, T COT, D ] D, DI, P, LL0 Back Scale (extended) LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 Donated by Bill Boas, Lakewood, CO. Purchased in 1993 directly from the Skyline store in Denver before they ended the business

Zodiak Instrument Sales, CA

ISRM Zodiak No 150 Duplex Log Log Trig

Zodiak No 150 Duplex Log Log Trig Made in Japan by Relay for Zodiak Instrument Sales,CA.- dc DK-4 (1955) Front Scale (Trig scales:Deg-Min-Sec) LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 Donated by David Hecht, Alexandria, VA

Year Codes
First letter in Date Code Example: J.K-1 = 1961

A	B	C	D	E	F	G	H	I	J	K	L	M
1952	1953	1954	1955	1956	1957	1958	1959	1960	1961	1962	1963	1964
N	O	P	Q	R	S	T	U	V	W	X	Y	Z
1965	1966	1967	1968	1969	1970	1971	1972	1973	1974	1975	1976	1977