Tape measure

How it works

The user draws the blade from the case and reads the length against its graduations. In a spring tape, a flat spiral spring inside the case winds as the blade is drawn out and rewinds the blade when it is released. Fellows’s 1868 patent describes the spring fitted as in watches, its inner end on a central arbor and its outer end on the rim of a barrel, with a click that holds the tape at any desired position and lets it back at pleasure.

A steel blade with a concave-convex cross section stays straight when extended. Farrand’s 1922 patent describes a metallic ribbon curved in cross section, flexible enough to be coiled but stiff and resilient enough to remain straight, or return to straight, when released. The curve is what lets the blade reach across an opening unsupported.

For trade use the blade must be accurate within legal tolerances. NIST Handbook 44 sets the tolerance for metal tapes by length, from 1/32 inch for intervals of 6 feet or less to 1/4 inch for 81 to 100 feet, and requires short tapes not normally used under tension to be tested with no tension applied, supported on a flat horizontal surface. In Europe the Measuring Instruments Directive sets maximum permissible errors by accuracy class as a + bL millimeters, with an extra allowance where a terminal interval is bounded by a surface, which is the case at a hook or an end.

Anatomy

Case: Leather in early long tapes; Fellows’s 1868 case was molded of gum-lac and sawdust and colored with ivory-black; later cases are metal or plastic.
Blade (tape): Linen, wired linen or steel ribbon, graduated on its face; a pocket steel blade is curved in cross section so that it stands out straight.
Spring: A flat spiral spring in a barrel that rewinds the blade; absent in long hand-wound tapes and in Farrand’s 1922 holder, which fed the tape by hand.
Lock or click: A click or brake that holds the blade at a chosen length; Stanley introduced its sliding lock in 1963.
End hook: A fitting at the zero end that catches the work; the 2013 PowerLock is described by Stanley with a “Tru-Zero” end hook.

Variants

Long tape: A hand-wound tape of tens or hundreds of feet in a leather or metal case; the Science Museum Group holds a 40-foot tape in a leather case made to Chesterman’s patent.
Spring-return pocket tape: A short tape rewound by a spring; patented in the United States by Bangs (1864) and Fellows (1868), both of New Haven County, Connecticut.
Curved steel pocket tape: A steel blade of concave-convex section that stands out when extended; Farrand’s 1922 patent describes it.
Power-return locking tape: The D-shaped PowerLock of 1963, with a coilable spring and sliding lock, which Stanley says remains the core of modern designs.
Dip and strapping tapes: Special accuracy classes D and S in the European directive, for dipping tanks and strapping tanks.

Specifications

Length · ft or m: 25 ftThe 2013 PowerLock anniversary tapes are 25-foot tapes; NIST tests tapes of 25 ft (10 m) or over at a 10 lb (5 kg) load.
Standout · ft: Stanley claims 7 feet of standout for its 2013 PowerLock tapes; this is a manufacturer claim, and no independent standout test has been sourced.
Tolerance (US, metal tapes) · in: 1/16 in for 7 to 30 ftNIST Handbook 44, Table 2: 1/32 in to 6 ft; 1/16 in, 7–30 ft; 1/8 in, 31–55 ft; 3/16 in, 56–80 ft; 1/4 in, 81–100 ft.
Maximum permissible error (EU) · mm: a + bL, with L in whole meters: Class I a = 0.1, b = 0.1; Class II a = 0.3, b = 0.2; Class III a = 0.6, b = 0.4; plus c (0.1, 0.2, 0.3 mm) where an interval is bounded by a surface.

Made to

NIST HB44-5-52
EU MID-MI-008
OIML R.35

Tips

The end hook is built to move
The hook on a modern tape is riveted so that it slides along the blade through a travel equal to its own thickness. Tallon’s 2009 patent says this lets the tape be used “butt-on,” with the hook pushed against a surface, or “hook-on,” with the hook pulled over an edge, giving a true zero in both. Rutty’s 1984 patent for The Stanley Works reached the same result with a hinged hook offset by the thickness of the metal, and describes the ordinary fixed hook as introducing an inaccuracy in inside measurements.1 2
Use the 16-inch stud marks
Stanley lists 16-inch and 19.2-inch stud center markings as a feature of its Powerlock tape, to simplify framing jobs. Griffith’s 1916 estimating chapter counts studs on the basis of walls and partitions specified 16 inches on centers, which is the spacing the mark locates.1 2
Use the 19.2-inch diamonds for trusses and floor joists
West Fraser, a producer of wood panels, says the black diamonds start at 19.2 inches and are used to space floor trusses under a 4 by 8 panel with a 20 inch span rating. It explains that a panel has 5 open bays and 5 joists, and that 96 inches (8 feet) divided by 5 bays gives the 19.2 inch spacing.1
Support a long tape along its length
Long, flat steel tapes sag if they are not supported over their full length, and the manual says lack of support can cause reading errors. The hook at the end of the common steel tape allows one person to take all the readings.1
Use a magnetic hook on steel framing
Milwaukee states that the magnetic hook on its 16 foot wide blade tape attaches to EMT conduit and steel studs, and that its 16 foot reach allows long measurements to be taken alone. This is a manufacturer’s description; no independent test of the magnet’s holding force has been sourced.1

History

Earliest documented

1833

Sheffield, England

Grace’s Guide records that James Chesterman, who moved from London to Sheffield in 1821 and set up the Bow Works, patented a spring-return linen tape measure in 1833, and invented a woven “metallic” tape and a steel tape in 1842. The Science Museum Group holds a 40-foot flexible measuring tape in a leather case made to the patent of Chesterman and his partner.1 2

The pocket tape measure is a nineteenth-century answer to a problem the folding rule already solved for short work: carrying a long, accurate length in a small space. The first form recorded here was textile. Grace’s Guide credits James Chesterman of Sheffield with a patented spring-return linen tape in 1833 and with woven “metallic” and steel tapes in 1842, and Chesterman’s firm was still making linen tapes in the 1920s, according to the Science Museum Group’s dated examples. The European directive now confines measures made from material whose dimensions may alter materially with humidity to its two lower accuracy classes, Classes II and III.

The spring and the catch were worked out in Connecticut in the 1860s. Bangs’s 1864 patent describes a spring tape-measure with a click mechanism “in general use” at the time and improves it by making the click part of the spring. Fellows’s 1868 patent claims a particular arrangement of a click that holds the tape at any position and releases it at will, and states that metallic cases with a click and release knob were already known. The patents themselves therefore show a run of incremental improvements on an existing device, with no single inventor of the locking tape.

Steel changed what a tape could do. Lufkin, founded to make log rules for the logging industry, says it introduced the first steel measuring tape produced in the United States in 1890. Farrand’s 1922 patent adds the property that defines the modern pocket tape: a steel ribbon curved in cross section so that it stays straight when pushed out, yet can still be coiled. His holder had no return spring; the tape was fed out by hand and held by a brake. Stanley says it introduced its first steel tape rule in 1931.

The modern form arrived in 1963 with Stanley’s PowerLock, which the company describes as combining a coilable spring and a sliding lock in a D-shaped case and as the core of designs that followed. Lufkin’s own history says the folding rule remained the dominant measuring tool of the trades until the 1940s, when the retractable tape became practical.

A tape measure is also a regulated measuring instrument. NIST Handbook 44 requires flexible tapes in its code to be metal and sets tolerances for metal tapes by length. The European directive takes a different approach, expressing the permissible error as a formula in two constants that change by accuracy class, with an added allowance at an end bounded by a surface.

Timeline

1821
James Chesterman moves from London to Sheffield and sets up the Bow Works in Nursery Street.1
1833
Chesterman patents a spring-return linen tape measure.1
1842
Chesterman introduces a woven “metallic” tape and a steel tape.1
1864
William H. Bangs Jr. of West Meriden, Connecticut, patents an improved spring tape-measure in which the click is an extension of the spring itself (US Patent 45,372).1
1868
Alvin J. Fellows of New Haven patents a spring tape whose click holds the tape at any desired position (US Patent 79,965).1
1869
Edward Taylor Lufkin founds the E. T. Lufkin Board and Log Rule Manufacturing Company in Cleveland, Ohio, to serve the logging industry.1
1890
Lufkin introduces what the company calls the first steel measuring tape produced in the United States.1
1922
Hiram A. Farrand of Merchantville, New Jersey, is granted US Patent 1,402,589 for a measuring tape of concave-convex steel ribbon stiff enough to stand straight, in a simple holder with a brake.1
1923–1928
J. Chesterman & Co. make a 12-foot linen tape later given to the Science Museum by Stanley Tools and Chesterman.1
1931
Stanley says it introduces the first steel tape rule.1
1963
Stanley introduces the D-shaped PowerLock tape rule, which the company describes as having the world’s first coilable spring and sliding lock.1 2
1972
NIST Handbook 44 amends its test rules for metal tapes: 5 kg (10 lb) tension for tapes of 10 m (25 ft) or over, 2.5 kg (5 lb) for shorter tapes, and none for short tapes not normally used under tension.1
2014
The European Measuring Instruments Directive (2014/32/EU) sets accuracy classes I, II and III, and special classes D and S, for material measures of length.1

Where the sources disagree

Who made the first steel tape, and when?

James Chesterman of Sheffield produced a steel tape in 1842.1
Grace’s Guide
Lufkin introduced the first steel measuring tape produced in the United States in 1890.1
Crescent Lufkin (company history)
Stanley introduced the first steel tape rule in 1931.1
Stanley Tools (company history)

Who first made a spring tape that locks?

Fellows’s 1868 patent claims a click that holds the tape at any desired position; the patent itself disclaims earlier metallic cases with a click and release knob.1
US Patent 79,965
A click mechanism was already in general use in spring tape-measures in 1864, when Bangs patented an improved one.1
US Patent 45,372
The 1963 PowerLock had the world’s first coilable spring and sliding lock.1
Stanley Tools (press release)

Gaps in the record (6)

Many secondary accounts date Chesterman’s first tape patent to 1829; Grace’s Guide gives 1833. The British patent itself has not been located and read, so the earliest date stands at 1833 and the 1829 claim is unverified.
The Science Museum Group titles its object “Chesterman & Rottom’s patent,” while Grace’s Guide names the partnership Chesterman and Bottom; the spelling is unresolved.
The Smithsonian’s National Museum of American History holds Lufkin tapes, but its site is not reachable from here and its records have not been read.
Stanley’s PowerLock patent number and text have not been located.
No independent test of blade standout, hook accuracy or durability has been sourced, so buying is null.
No sourced safety or care entries.