Acu-Rule,  Acu-Math, (and later Sterling Plastics) slide rules were made originally by Festus Mfg. Co., Festus, Missouri, in 1938 by Paul Jones. In 1939 the company was renamed  Acu-Rule Co., and later moved to ST. Louis, Missouri. then moved to in Mt. Olive, Illinois in 1954. Acu-Math became the standard brand which was retained when merged later as the Acu-Math Division of Sterling Plastics in Mountainside, New Jersey in 1968 and was purchased and produced by Borden Chemical Co. up until the mid 1970's. Click here for more Acu-Rule History.



S527 Festus - Lucite Cursor
Festus - Lucite Cursor - c1938
Made in USA by Festus Mfg, Festus, MO. - Paper on wood scales
Front Scale
10in // A [ B, CI, C ] D, K || 25cm
Back scale: [S, L, T ]
Back: equivalents - Paper glued on wood
Note: Same stock as Acu-Rule 100, except paper scales


REF Acu-Rule 10-J
Acu-rule 10-J - c1939
Made in USA by Festus Mfg in Festus, MO
Front Scale
A [ B, CI, C ] D, K
Back Slider: Blank
Back: Conversion Chart, 25cm
Archive - Tom Dilatush Collection


S343
Festus (pre-Acu-Rule 100)
Festus (pre-Acu-Rule 100)  Magnifying Cursor - c1939
Made in USA by Festus Mfg., Festus, MO.
Front Scale
A [ B, CI, C ] D, K
Back scale: 25cm [S, L, T ] 10in
Back: equivalents
Note: Same scales as Acu-Rule 100, except no beveled edge


S289 Acu-Rule 10-D 
Acu-rule 10-D - Magnifier- c1938
Made in USA by Festus Mfg in Festus, MO
Front Scale
A [ B, CI, C ] D, K
Back Slider: Blank
Back: Conversion Chart


P260 Acu-Rule 5-J  Pocket
Acu-Rule 5-J Pocket - Wood - c1940
Made in USA by Festus Mfg., Festus, MO.
Front Scale
A [ B, CI, C ] D, K
Back Slider: Blank
Back: 13Cm, 5 in
Back Adv: Security Engineering Co.


S050 Acu-Rule
100
Acu-Rule 100  - Wood - c1939
Made in USA by Festus Mfg.
Front Scale
Inch // A [ B, CI, C ] D, K
Back Slider
Cm [ S, L, T ]
Back: Conversion Chart


REF Acu-math AREL G-W Photo SR
Acu-math AREL G-W Photo SR - 1946
Made in USA - Wood Stock, brass stiffener, Plastic Laminate, Molded cursor
Front Scale
F, WESTON, ASA [ Daylight, LIGHT, SKY TYPE, SUBJECT, FILTER, GAMMA] DEPTH of FOCUS
Back: Film Speed Indexs
Archive - George Keane Collection
Instructions 3.31MB


REF Acu-math_4
Acu-math 4 -  c1965
Made in USA - Note: Stock is only 28mm wide - Magnifying cursor
Front Scale
K, A [ B, CI, C ] D, L
Back Scale: Blank
Archive - George Keane Collection

Plastic Clamshell case logo


P114 Acu-math 12 pocket
Acu-math 12 - c1965
Made in USA - Note: This is the ONLY yellow Acu-Math I've seen
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ]



REF Acu-math A-60 Log Log Decimal Trig
Acu-math A-60 Log Log Decimal Trig - c 1945
Made in USA by Acu Design (ST. Louis)- Early Magnesium with finger pocket
Front Scale
T, DF [ CF, CIF, CI, C ] D, S Cos, ST
Back Scale
LL0, LL00, A [ B, K, L, C ] LL3, LL2, LL1
Archive - Tom Dilatush Collection


REF Acu-math A-80
Acu-math A-80 - c 1945
Made in USA by Acu Design (ST. Louis)- Early Magnesium with finger pocket
Front Scale
K, A [ B, S, T, C ] D, S, DI
Back Scale: Note Folded scales
Equivalents, [ L, C2, C1 ] D1, D2, D
Archive - Tom Dilatush Collection


S241 Acu-math 90 Mannheim
Acu-math 90 Mannheim - c1945
Made in USA - Acu Design - Early Magnesium with finger pocket
Front Scale
T, DF, A [ CF, CIF, CI, C ] D, S, ST
Back Scale
Equivalents [ B, K, L, C ] Equivalents



S469 Acu-math 90A Mannheim
Trig
Acu-math 90A Mannheim Trig - c 1945
Made in USA by Acu Design (ST. Louis)- Early Magnesium with finger pocket
Front Scale
T, DF [ CF, CIF, CI, C ] D, S Cos, ST
Back Scale
Equivalents, A [ B, K, L, C ] Equivalents



S168 Acu-math 150 Duplex Log Log Decimal Trig
Acu-math 150 - Duplex Log Log Decimal Trig - c1968
Made in USA
Front Scale
LL01, K, A [ B, T, ST, S ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2



S142 Fullerton-Acu 400
Fullerton-Acu 400 - Simplex Trig - c1968
Made in USA
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Blank



S141 Acu-math 400
Acu-math 400 - Simplex Trig -  c1968
Made in USA - note round corners
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Blank



S140 Acu-math 400
Acu-math 400 - Simplex Trig - c1968
Made in USA - Note square corners
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Blank



S051 Acu-math 400B
Acu-math 400B - Simplex Trig - c1965
Made in USA
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S139 Acu-math 500
Acu-math 500 - Simplex Trig - 1960
Made in USA
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S137 Acu-math 500
Acu-math 500 - Simplex Trig - c1968
Made in USA
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S447 Acu-math 511 Student Mannheim
Acu-math 511 Student Mannheim -c 1945
Made in USA - Early Magnesium with finger pocket
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



REF Acu-Math 511 Professional Mannheim
Acu-Math 511 Professional Mannheim c1960
Made in USA - Note: Stock/Slide has a plastic laminate over alloy substrate.
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties
Archive - Now in Duncan MacKellar collection



S224 Acu-Math 511 Professional Mannheim
Acu-Math 511 Professional Mannheim - c1955
Made in USA - Note: this has a painted all-metal stock and a single sided cursor to reduce manufacturing cost. The cursor is retained by grooves on the stock.
Front Scale
S, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



REF Acu-math 550
Acu-math 550 - Professional Mannheim Trig -c1960
Made in USA by Acu-Rule
Front Scale
K, A [ B, T Cot, ST, S Cos] D, DI, L
Back Scale
Conversions, DF [ CF, CIF, CI, C ] D, Conversions, con't.
Archive - Tom Dilatush Collection


S427 Acu-math 600 Basic Trig
Acu-math 600 Basic Trig - c1955
Made in USA
Front Scale
S, S&T, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S482 Acu-math 600 Basic Trig
Acu-math 600 Basic Trig - 1955
note: double end plates- simplex cursor - all plastic stock
Made in USA
Front Scale
S, S&T, K, A [ B, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S138 Acu-math 500
Acu-math 600 - Simplex Trig - c1968
Made in USA
Front Scale
K, A [ B, S, ST, CI, C ] D, L, T
Back Scale
Conversion Table [Fraction=Decimal] Trig properties



S522 Acu-Rule MR700 Mu-Stick
Chord/note transposition
Acu-Rule MR700 Mu-Stick - Key transposition - c1965
Made in USA - Distributed by Mel McSwain Co.
Front Scale
Original Key [ Transposed Key ] Diminished/Augmented
Back: Blank



S418 Acu-math 800 Accu-Line
Acu-math 800 Accu-Line - c1968
Made in USA
Front Scale
LL01, K, A [ B, T Cot, ST, S  Cos] D, DI, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2
Note: Adjustable cursor alignment



S136 Acu-math 900
Acu-math 900 - Professional Mannheim Trig -c1955
Made in USA - Note: metal ends both sides
Front Scale
K, A [ B, T Cot, ST, S  Cos] D, DI, L
Back Scale
Conversions, DF [ CF, CIF, CI, C ] D, Conversions, con't.




S047 Acu-math 900
Acu-math 900 - Professional Mannheim Trig - c1960
Made in USA - Note metal ends only on one side
Front Scale
K, A [ B, T Cot, ST, S  Cos] D, DI, L
Back Scale
Conversions, DF [ CF, CIF, CI, C ] D, Conversions, con't.



P037 Acu-math 1200
Acu-math 1200 - Pocket Simplex - c1965
Made in USA
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ]



P065 Acu-math 1200
Acu-math 1200 - Pocket Simplex - c1965
Made in USA - Note: Black End pieces, NIB
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ]



P005 Fullerton-Acu 1200
Fullerton-Acu 1200 - Pocket Simplex - c1965
Made in USA
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ]



P229 Acu-Math 1211 Pocket - Pre Acu-Math Logo
Acu-Math 1211 - Pocket duplex - c1965
Made in USA - Plastic laminate on Magnesium Stock - Metal Ends
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ] Multi-lined cursor



P036 Acu-Math 1211
Acu-Math 1211 - Pocket Simplex - c1955
Made in USA - Metal Ends
Front Scale
K, A [ B, CI, C ] D, L
Back Scale
[ S, T ] Multi-lined cursor



P005 Acu-Math 1240
Acu-Math 1240 - Pocket Simplex - c1965
Made in USA
Front Scale
K, A [ B, CI, C ] D, L
Back Scale: None



S097 Acu-math 1300
Acu-math 1300 - Duplex Log Log Decimal Trig -c1960
Made in USA
Front Scale
LL01, K, A [ B, T Cot, ST, S Cos ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2



S398 Acu-math 1311 Log Log Decimal Trig
Acu-math 1311 - Duplex Log Log Decimal Trig -c1945
Made in USA - Note: Finger detents on slide
Front Scale
LL01, K, A [ B, T Cot, ST, S Cos ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2
Early Magnesium Model - narrow cursor


S375 Acu-math 1311 Log Log Decimal Trig
Acu-math 1311 - Duplex Log Log Decimal Trig
Made in USA - Note: Braces on both sides
Front Scale
LL01, K, A [ B, T Cot, ST, S Cos ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2
Magnesium Model


S134 Acu-math 1311
Acu-math 1311 - Duplex Log Log Decimal Trig-c1950
Made in USA - Note: Braces only on one side
Front Scale
LL01, K, A [ B, T Cot, ST, S Cos ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2



S388 Acu-Math 1500 Log Log Decimal Trig
Acu-Math 1500 Log Log Decimal Trig -c1961
Made in USA - has U.S. (military)
Front Scale
LL01, K, A [ B, T, ST, S ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2



S135 Acu-math 1500
Acu-math 1500 - Duplex Log Log Decimal Trig - c1968
Made in USA
Front Scale
LL01, K, A [ B, T, ST, S ] D, L, LL1
Back Scale
LL02, LL03, DF [ CF, CIF, CI, C ] D, LL3, LL2



S400 Acu-math  C.V. Ore  - No. 1155
Acu-math C.V. Ore -  S-M No. 1155
Made in USA by Acu-Rule Co. for C.V. Ore, Harvey, Illinois - 1955
Front Scale: DS [ CI, C ] DM
Back Scale: Blank
Note: This may be a Statistical slide rule, where DM is the Mean and the DS the Standard, or it could be a basic teaching rule using integers for simplicity.


S475 Connecticut Spring Corp Spring Design
Connecticut Spring Corp Spring Design - c1945
Made by Acu-Rule for Connecticut Spring, Hartford, CT.
Magnesium stock
Front Scale
Wire Size [ Wire Size, Load, Ratio D/d, Rect: ratio b/t ] Lbs per Inch Deflection
Back Scale
Mean Dia [ Mean Dia, Active coils, G, Rect: ratio b/t ] Stress
Archive - Billy Guthrie collection
Instructions 3.31MB


S475 Connecticut Spring Corp Spring Design
Connecticut Spring Corp Spring Design - c1955
Made by Acu-Rule for Connecticut Spring, Hartford, CT.
All plastic stock
Front Scale (Step 1 -design spring force)
Wire Size [ Mean Dia., Active Coils, Rect: ratio b/t ] Lbs per Inch Deflection
Back Scale (Step 2 - determine design stress)
Mean Dia [ Wires Size, Load, Ratio: D/d, Rect: ratio b/t ] Stress
Note: Compare spring design scales with the Pickett ASC slide rules and manuals.
Instructions 3.31MB

Acu-Rule was also an OEM to other slide rule manufacturers and distributors.
Here is an example



S442 Dietzgen 1757 Primatrig
Dietzgen 1757 Primatrig - c1955
Made in USA by Acu-Rule for Dietzgen - All Plastic Stock/slide, metal ends. Similar to (S427) Acu-Math 600 Basic Trig
Front Scale
L, K, A [ B, CI, C ] D, T Cot, ST, S Cos
Rear Scale
Trig Identities [ Decimal to Fractions ] Equivalents

Same as S427 Acu-Math 600 Basic Trig (scales rearranged)

Acu-Rule (1939) and Acu-Math (1961) Catalog Spec sheets

2.27MB
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