USD $35
A compact 90mm/3 inch pocket circular slide rule with metric conversion factors and temperature conversion on the reverse side. Cursor has scale names imprinted, as well as the rule body. Excellent quality compact rule, complete with vinyl slip case and factory manual.
BRAND NEW, complete with WHITE vinyl case and manual. These fit perfectly in a shirt pocket!
(8 Scales, Metric + Temperature Data)
Front – L, D, C, CI, A, K, S, T, K
Back – Metric + Temperature Data
Stock: 10
USD $35
A compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card with pull-out insert. The rear side has a metric data conversion table, the center has a pull out unit conversion data chart with prefix terms. Ideal for those working with metric and imperial units. Very nice rule, complete with vinyl slip case and manual.
BRAND NEW, complete with vinyl case and manual.(8 Scales, Side Rulers, Metric Data + Factor Conversion Data Card)
Front – D, C, CI, L, A, S, T, K
Back – Metric Data
Inside – Data Card, Factor Conversion Data
Stock: 17
USD $11
Great for the business person on the go, or anyone concern with turning a profit. Usage instructions printed on reverse side.
Stock: Lots
USD $25
Despite the prevalence of smart phones, some times you need a classic. Produced in 2015, is this universal date finder circular slide chart, with usage instructions printed on the back.
Y2K compliant!
Stock: 3
USD $79
The 600CE is a compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card (with side inch/cm rulers) complete with pull-out chemical data insert. The rear side has a Detailed Periodic Table of the Elements (to 103), the center has a pull out data chart with the full CE double sided data chart. These rules were re-branded by various companies for promotional use, and come with original vinyl slip case and manual.
THIS IS THE MOST REQUESTED Data Center from Sama and Etani. Sama and Etani had to stop production of these rules many years ago because teachers complained students used them to cheat on exams, and so a fantastic reference tool was lost forever. This is a VERY hard rule for us to source, so please don’t miss your chance to get one!
(8 Scales, 2 side rulers, Periodic Table + Data Card)
Front – D, C, CI, L, A, S, T, K
Back – Periodic Table
Inside – Data Card, Chemical Engineering
Stock: 7
USD $79
A compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card with pull-out insert. The rear side has a metric data conversion table, the center has a pull out data chart physical data, constants, formulas and terms. This rule is ideal for chemists, lab techs, and enthusiasts of quality pocket rules. These rules were branded by various companies for promotional purposes, and come in an assortment of case colors (red, black, white).
BRAND NEW, complete with vinyl case and manual.
(6 Scales, Side Rulers, Chemical/Element data)
Front – D, C, CI, L, A, K
Back – Table of Elements
Inside – Data Card (gas constants, velocities, flow rates, etc)
Stock: 4
USD $10
4″ Pocket Date Finder Circular Slide Chart
Stock: Lots
USD $35
A compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card with pull-out insert. The rear side has a metric data conversion table, the center has a pull out data chart physical data, constants, formulas and terms. Ideal for those in any general science area working with metric units. Very nice rule, complete with red vinyl slip case and manual.
BRAND NEW, complete with vinyl case and manual.
(8 Scales, Side Rulers, Metric Data + Physical Data Card)
Front – D, C, CI, L, A, S, T, K
Back – Metric Data
Inside – Data Card, Physical Data
Stock: 16
USD $44
Very similar to the Type E rule by Concise, this circular rule features most of the same features in the original Japanese. 5 scales, with weights and measure conversion tables on the slide out data card.
Includes original vinyl slipcase, and instruction booklet.
(5 Scales, Conversion data card)
Front – D, C, CI, A, K
Back – Conversion reference table guide
Stock: 1
USD $45
A compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card with pull-out insert. The rear side has a color coded reactance chart, the center has a pull out data chart with color codes, wire data, constants, formulas and terms. An outstanding and useful device, incredibly handy if you are in the electronics industry. These fit perfectly in a shirt pocket. Complete with vinyl slip case and manual.
(8 Scales, Side Rulers, Reactance Chart + Data Card)
Front – D, C, CI, L, A, S, T, K
Back – Reactance Chart Inside – Data Card, Electronics
Stock: 7
USD $35
This circular rule is for the person doing conversions on the go, and features a pared back set of scales to make room for a robust set of conversion factors using the slide out data card for any unitary conversion a tradesman might need. A fine addition to any shirt pocket, daytimer, or field notebook.
Includes original vinyl slipcase, and instruction booklet.
(5 Scales, Conversion data card)
Front – D, C, CI, A, K
Back – Conversion reference table guide
Stock: 1
USD $39
A more advanced, but still very clean looking and easy to read circular slide rule. Includes original vinyl slip case and instruction manual.
(12 scales)
Front – L, D, C, CI, A, K
Back – DI, D, S, T1, T2, ST
Stock: 2
USD $8
A purpose built circular slide chart for selecting lens size based on CCTV sensor size, vertical and horizontal object dimensions, and object distance. Usage instructions included on the reverse side of the calculator.
Stock: 17
USD $33
The Hope 740 is another custom rule made by Concise and marketed under another label, in this case Hope, who offered both circular and straight rules from Japan. The 740 is a metric converter built on the Concise data center ‘chassis’. The front is a compact 3 inch pocket circular slide rule, attached to a rectangular data center card (with side inch/cm rulers on the back). The rear side has a C/F temperature scale, inch and centimeter rulers and a nice table of constants. A very handy rule for quick conversions of temperature, length, volume, weight and area, PLUS an extra C/D scale set for general calculations. Complete with black/clear vinyl slip case, and short factory manual, all in MINT CONDITION!
This ia a very nice looking item from Concise that will be very handy in your shirt pocket!
(4 Scales, 2 back rulers, Constants)
Front – VOL/WEIGHT/AREA/LENGTH C, D
Back – Rulers, Constants
Stock: 2
USD $35
A classic and easy to read circular rule, great for beginners or those looking for their first circular rule.
(5 scales, conversion factors)
Front – D, C, CI, A, K
Back – Metric / imperial conversions
Stock: 1
USD $35
A compact 2 1/2 inch pocket circular slide rule, attached to a rectangular data center card with pull-out insert. The rear side has a metric data conversion table, the center has a pull out data chart with color codes, wire data, constants, formulas and terms. Ideal for those in the electronics industry working with metric units. Very nice rule, complete with vinyl slip case and manual.
Complete with vinyl case and manual.(8 Scales, Side Rulers, Metric Data + Electronics Data Card)
(8 scales, 2 rulers, data card, and metric conversions)
Front – D, C, CI, L, A, S, T, K
Back – Metric Data
Inside – Data Card, Electronics
Stock: 1
USD $310
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, wind drift, time, temperature, and fuel problems. The 617 features an additional rotating wind arrow on the back face, not present on other models.
The rule gives simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch. Comes with the original English manual and leather case (case has some wear and seam pulling).
(22 scales on front, Wind scales on rear)
Stock: 1
USD $8
Profit Calculator 5″ Circular Slide Rule
Stock: 1
USD $45
Concise Permanent Calendar & World Time Pocket Circular Slide Rule w/Case & Manual (Japanese)
Stock: 1
USD $10
This convenient pocket rule uses distance, voltage, and current to determine wire/cable gauge. Instructions are printed directly on the front of the rule, and the reverse side contains a reference table of copper wire data.
Stock: 1
USD $10
PS 69 Proportional Scale 5″ Circular Slide Rule, usage instructions printed directly on the front side of the rule.
Stock: 1
USD $55
Pocket circular slide rule for for converting between world time zones, includes the original case, in Japanese.
Stock: 1
USD $65
Pickett 106C Proportional Scale 6″ Circular Slide Rule
Stock: 1
USD $15
Williams Decimal & Metric Equivalent Pocket Circular Slide Rule
Stock: 4
USD $25
Pediatric Dial-A-Dose Circular Slide Rule w/Instructions
Stock: 1
USD $15
A useful pocket metric/imperial pocket converter that does weights, volumes, and temperature on one side, and area and length on the reverse side.
Stock: 1
USD $49
This is a specialist rule for calculating resistance attenuation in 600 ohm circuits, using impedance, voltage, and resistance. Includes the original case and instruction manual.
Stock: 1
USD $85
This is a very minimalist circular pocket rule that looks to have only three scales, with a concentrically mounted rotating scale and adjustable cursor. Appears to be for doing multiplication and division, as well as percentages.
Stock: 1
USD $125
This is a beautiful, metal body, simplex, circular rule in excellent condition. We are unfortunately unable to give a great deal more depth on the rule due to most of the documentation we have on it being in German, but both the case and rule are in excellent condition.
Stock: 1
USD $95
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. This flight computer handles altitude, pressure, wind drift, time, temperature, and fuel problems.
The rule gives calculations primarily in US/Imperial units, with some calculations available in metric.
Stock: 1
USD $225
Uncommon Faber-Castell circular, plastic body rule with rotating scale and 7 line cursor, two color (red/black) scale markings, trademark mint green accent stripes on primary scales, yellow stripes on dual cycle scales, and expanded trig scales. The rule is self documenting on right hand side for all scales, the back is blank. An exceptionally high quality and attractive circular rule, seldom seen outside of Europe.
There are two versions of this rule, one where the reverse side is blank, and one with setting data (in German – this rule, see photo). The set comes with the original zippered leather case with gold logo embossed in the leather, and original German manual.
(11 Scales)
Front – K, A, L, D, [ C, CI, B, T1, T2, S, ST ]
Stock: 1
USD $75
This is a larger, 6″ circular flight computer, featuring a variety of functions on the front side for calculating air speed, fuel consumption, distance, and altitude/temperature adjustments. The reverse side features a cross-wind calculator.
Includes the original case and operating manual.
Stock: 1
USD $175
Gilson’s most famous aluminum circular slide rule, with alternating yellow/white stripes and fractional converter/operator scales. This rule was made by Gilson in Florida but was also sold by numerous other companies, this is the Dietzgen version (slightly green tinted). This is a very powerful rule, with 3 sets of trig scales (sin/tan), giving performance equal to a much larger straight rule, and still has the factory box, and original printed manual.
The rule has unique fractional ‘binary’ scales that permit operations directly with fractional numbers, and also drill size scales. Rotating dual cursors with a slip clutch on one side, and a single cursor on the other.
(21 Scales !)
Front – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back – degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 2
USD $175
Gilson’s most famous aluminum circular slide rule, with alternating yellow/white stripes and fractional converter/operator scales. This rule was made by Gilson in Florida but was also sold by numerous other companies, this is the Dietzgen version (slightly green tinted). This is a very powerful rule, with 3 sets of trig scales (sin/tan), giving performance equal to a much larger straight rule, and still has the factory box, and original printed manual.
The rule has unique fractional ‘binary’ scales that permit operations directly with fractional numbers, and also drill size scales. Rotating dual cursors with a slip clutch on one side, and a single cursor on the other.
(21 Scales)
Front – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back – degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 1
USD $65
This is a larger, 6″ circular flight computer, featuring a variety of functions on the front side for calculating air speed, fuel consumption, distance, and altitude/temperature adjustments. The reverse side features a cross-wind calculator.
Includes the original case, which has a torn edge.
Stock: 1
USD $125
This flight computer features a variety of functions on the front side for calculating air speed, fuel consumption, distance, and altitude/temperature adjustments. The reverse side features a cross-wind calculator.
This rule is a smaller version of the CR-3, and includes the original case.
Stock: 1
USD $125
This duplex circular rule looks to have 15 scales, and includes its original manual and case.
Stock: 1
USD $59
4 Inch Simplex Circular
Pickett’s popular plastic commercial circular slide rule, with mark-up and discount functions. Very nice rule, with operating instructions on the face, used excellent condition. Convenient pocket size, very hard to find!
(4 Scales + directions)
Front – Profit mark up , Unit Cost, Profit Margin %, Discount %
Back – Blank
Stock: 3
USD $75
This is an unusual rule created by Tektronix for circuit computations, accounting for frequency, resistance, capacitance, and inductance. The front of the rule features the various calculation scales, and the back of the rule features reference formulas.
Stock: 1
USD $45
This is a very thorough and intuitive conversion set created by Pickett which uses interchangeable discs secured by a thumb screw to modify the rule for different unit conversions. The rule also features C & D scales for multiplication and division.
The original packaging is included, which features detailed and easy to understand operating instructions.
Stock: 1
USD $89
8 Inch Simplex Circular
Pickett’s popular full-sized plastic commercial circular slide rule, with mark-up, margin and discount functions. Very nice rule, with operating instructions right on the face, very good condition. This has a few surface scuffs, but as you can see, they do not affect operation at all.
(4 Scales + directions)
Front – Profit mark up , Unit Cost, Profit Margin %, Discount %
Back – Blank
Stock: 1
USD $265
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, time, temperature, and fuel problems.
The rule give simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch, reprint English manual, and original German manual.
Stock: 1
USD $245
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, wind drift, time, temperature, and fuel problems. The 617 features an additional rotating wind arrow on the back face, not present on other models.
The rule gives simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch. Comes with an English manual reprint, and original German language manual.
(22 scales on front, Wind scales on rear)
Stock: 1
USD $285
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, wind drift, time, temperature, and fuel problems.
The rule gives simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch. This rule is in excellent condition, and the case is in fair condition (some scuffs/marking). The similar 617 has an additional rotating wind arrow on the back face, not present on these models. Comes with an English manual reprint, and original German manual.
(22 scales on front, Wind scales on rear)
Stock: 1
USD $35
Originally designed as Geocaching coins by Dutch Geocacher Technetium, these Pale Horse Designs coins are a unique slide rule item. The core is die cast zinc alloy to achieve the high detail, with either gold or silver toned plating, or nickel plating, depending on the design. The inner triangle design is Sierpiski’s fractal triangle. Each coin comes inside a clear plastic display carrier, and a padded cardboard display box with cutout for viewing the coin.
The Sunlight Coin is satin gold and silver finish with a jade accent, and is both a wonderful aesthetic addition to any collection, as well as having a unique feel, with a working slide rule on the face (the two outer scales are C and D, the innermost is a Log Log scale, and smith chart on the reverse). These 50mm diameter coins are heavy and thick (5mm), not a flimsy plastic item, but a solid metal good luck piece or pocket fancy you will enjoy for a long time.
The Midnight and Sunlight coins can be purchased as a set for $65, while quantities last.
We will not be doing any further production runs of these coins.
Stock: 15
USD $35
Originally designed as Geocaching coins by Dutch Geocacher Technetium, these Pale Horse Designs coins are a unique slide rule item. The core is die cast zinc alloy to achieve the high detail, with either gold or silver toned plating, or nickel plating, depending on the design. The inner triangle design is Sierpiski’s fractal triangle. Each coin comes inside a clear plastic display carrier, and a padded cardboard display box with cutout for viewing the coin.
The Midnight Coin is blue and nickel plated, and is both a wonderful aesthetic addition to any collection, as well as having a unique feel, with a working slide rule on the face (the two outer scales are C and D, the innermost is a Log Log scale, and smith chart on the reverse). These 50mm diameter coins are heavy and thick (5mm), not a flimsy plastic item, but a solid metal good luck piece or pocket fancy you will enjoy for a long time.
The Midnight and Sunlight coins can be purchased as a set for $65, while quantities last.
We will not be doing any further production runs of these coins.
Stock: 2
USD $159
M.H. Mear Gas Flow Calculator Circular Rule (new/mint)
Stock: 1
USD $59
Coast Navigation Simex Course Converter (new/mint)
Stock: 1
USD $85
Fearns W25 Castings and Forging Weight Calculator Circular Rule (new/mint). One with a green case and one with a brown case.
Stock: 2
USD $85
Fearns-Mear Machining Time Calculator Circular Rule (new/mint)
Stock: 2
USD $159
M.H. Mears Pipe Flow Calculator for Liquids & Gases (new/mint)
Stock: 1
USD $135
Concise No. 380 Radio Converter Circular Rule (new/mint), includes case and instruction manual.
Stock: 2
USD $85
Earns W28 Steelwork Weight Calculator Circular Slide Rule
Stock: 1
USD $59
Do you need to measure fallout radiation from a nuclear detonation? This is what you need to do that! I’m sure there are other ways, but this way will absolutely not fail you (doesn’t need batteries), so long as you are sufficiently far away to safely be able to operate the rule.
Stock: 3
USD $125
4 1/2″ Binary Pocket Circular Rule (in green)
(21 Scales !)
Front: – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back: degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 1
USD $125
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, wind drift, time, temperature, and fuel problems.
The rule gives simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch. We have had many requests for this rule from all over the world, this set is in very good condtion, except for a few case scuffs.
Stock: 1
USD $275
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, wind drift, time, temperature, and fuel problems.
The rule gives simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch. We have had many requests for this rule from all over the world, this are the first 618’s we have ever had available for sale, all in excellent condition. The similar 617 has an additional rotating wind arrow on the back face, not present on these models. The earlier 616 does not have the red reciprocal degrees printed on the rear compass rose, or the wind arrow.
(22 scales on front, Wind scales on rear)
Stock: 1
USD $95
Fearns A8 Metric Weight Converter, includes case and manual, one side converts imperial to metric, and the other metric to imperial.
Stock: 1
USD $255
5.5″ Circular Aviation Slide Rule
Constructed with one rotating film disk, and rotating cursor on each side. A very sophisticated and beautiful flight computer for doing altitude, pressure, time, temperature, and fuel problems.
The rule give simultaneous solutions in both metric and US/Imperial units, without being cluttered or hard to interpret, an outstanding mechanical and artistic design. Still in demand today among many pilots, but very hard to find.
Made of ‘Aristopal’, comes complete with zippered leather pouch.
Stock: 1
USD $125
4 1/2″ Binary Pocket Circular Rule
(21 Scales !)
Front: – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back: degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 1
USD $69
Concise Type E Pocket Circular Slide Rule w/Conversion Tables, includes original manual.
Scales: D, C, CI, A, K
Stock: 1
USD $165
nPK-69 Russian Dual Circular Slide Rule w/Chart – RARE.
Stock: 1
USD $249
Originally made by Gilson but sold under a number of different marques (e.g. Post, Dietzgen, Tavella, etc), this 21 scale rule is recognized for its high visibility alternating yellow and white rings.
The rule has unique fractional ‘binary’ scales that permit operations directly with fractional numbers, and also drill size scales. Rotating dual cursors with a slip clutch on one side, and a single cursor on the other.
This specific rule and its case are in above average condition.
Scales include:
Front – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back – degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 1
USD $220
Originally made by Gilson but sold under a number of different marques (e.g. Post, Dietzgen, Tavella, etc), this 21 scale rule is recognized for its high visibility alternating yellow and white rings.
The rule has unique fractional ‘binary’ scales that permit operations directly with fractional numbers, and also drill size scales. Rotating dual cursors with a slip clutch on one side, and a single cursor on the other.
This rule is in good condition, and the case is in acceptable condition with some fraying and marking.
Scales include:
Front – C, CI, A, K, L, Log Log (1.0015-1,000,000), fractions, fractions, drill/thread, mm
Back – degrees, sines, tans, degrees, sines, tans, degrees, sines, tans, Fractional Conversions
Stock: 2
USD $215
This is a single sided circular slide rule operated by using the two knobs on the top of the rule’s all metal casing. Some details on using these style of calculators can be found here. The Long Scale version of this calculator is specifically designed for use by engineers, draughtsman, and science students.
The designation of “long scale” (also some times called “magnum”) refers to this calculator being 1.5″ larger than the standard Fowlers Calculator, allowing for much finer gradation on the scales, and allowing calculations of four or five significant digits.
Stock: 1
USD $249
This is a very rare 4″ pocket circular rule, that comes with both the original factory box and manual in very good condition.
Scales include: A, C, CI, Log, Log-Log, Binary, S,
Stock: 1
Sphere Research Corporation