Framing square

How it works

The two arms are made at an exact right angle, so the outer edges mark a square line across a board. Hodgson gives the test still in use: mark a line along the tongue across a board with a trued edge, turn the square over, and check that the tongue falls on the same line.

For roof framing the square is used as a scale triangle. The carpenter sets the rise on one arm and the run on the other at the edge of the rafter stock; the two arms then give the plumb and level cuts. Hill’s 1879 article and Hodgson’s treatise work through rafters, braces and octagons this way.

The tables stamped on the square do the arithmetic. Howard’s 1881 patent puts on the square a table of rafter lengths for given spans at one-fourth, one-third and one-half pitch. Nicholls’s 1901 patent gives rows of figures under each inch mark for the length of common and of hip and valley rafters per foot of run, jack rafter lengths at 16 and 20 inches on center, and side cuts. Other standard scales are the brace measure, giving the length of a common brace for equal runs, the octagon or “eight-square” scale for cutting an octagonal stick from a square one, and a diagonal scale for taking off hundredths of an inch.

Anatomy

Blade (body): The longer, wider arm; 24 inches by 2 inches in good squares, according to Hill (1879) and Hodgson.
Tongue: The shorter, narrower arm; 14 to 18 inches long, according to Hill and Hodgson, and 1½ inches wide, according to Hodgson; the Vermont Historical Society’s nineteenth-century examples have 16-inch tongues.
Heel: The outside corner where the arms meet; a Shaftsbury square in the Vermont Historical Society is marked “Hardened corners.”
Graduations: Inches subdivided into halves through sixteenths on the outer edges and twelfths on an inner edge, with thirty-seconds on some squares, according to Hodgson’s ABC of the Steel Square.
Tables and scales: Rafter tables, brace measure, octagon scale, board measure and a diagonal hundredths scale, stamped or etched on the faces.

Variants

Plain steel square: Graduated arms with board and brace measure, such as the popular No. 100 described by Hodgson.
Rafter-table square: A square with rafter lengths per foot of run, of the kind patented by Nicholls in 1901.
Square with framing attachments: A square fitted with an adjustable stock or fence for repeating a pitch; Hodgson describes a “pitch-square” and Topp’s Framing Tool.
Combination square and level: A square with leveling glasses set in its arms; Hodgson reproduces such a patent and judges it more ornamental than useful.

Specifications

Blade · in: 24 × 2Hill (1879); Hodgson.
Tongue · in: 16 × 1½Hill and Hodgson give 14 to 18 inches long and Hodgson 1½ inches wide; the Vermont Historical Society’s Shaftsbury squares have 16-inch tongues.
Squareness tolerance · in: No standard or independent test of framing-square accuracy has been sourced.

Safety and care

Care

Do not use emery or sandpaper on nickel or black-finished squares; oil the square after use and do not put it away with finger marks on it, which cause rust (manufacturer’s directions for the Nicholls square, reproduced by Hodgson).
If the outer edges are found not straight or not true, file or grind them until they are (Hodgson).

Tips

Use the rafter table for length per foot of run
Griffith explains that carpenters found the rafter length increases in proportion for every foot of run, so a table of lengths per foot of run replaces a solution of the right triangle. Twelve inches is taken on the tongue as the run, the rise per foot is found on the outer edge of the blade, and the number directly below it is the common rafter length per foot of run. His worked example for quarter pitch uses 13.42 inches per foot, and 12.5 feet of run times 13.42 inches is 167.75 inches.1
Step off the plumb cut at 12 and the rise
To lay out a common rafter, the square is placed with 12 inches on the tongue as the run and the rise per foot of run on the blade, both numbers kept against the top edge, and the cut is scribed along the blade. Griffith notes that the order of tongue and blade may be reversed so long as it is kept consistent.1
Use the Essex board measure for lumber
The manual describes the Essex board measure on the back of the square as a table for the board feet in a piece of lumber. Hodgson explains that the 12 inch mark stands for a one inch board 12 inches wide, the starting point, and that the length is read on the line below it: a board 8 feet long and 6 inches wide measures 4 board feet.1 2
Use the brace rule for common braces
The manual lists the brace measure among the tables on the back of the square as the means of finding the exact length of common braces. Hodgson’s simpler case is a brace with a three-foot run on both post and beam, laid out by taking 12 inches on the tongue and 12 on the blade and stepping the distance three times along a straight line.1 2
Use the octagon scale to cut an eight-sided stick
The octagon scale runs along the middle of the face of the tongue. Hodgson describes taking as many spaces from the scale as there are inches in the width of a square stick and laying that space off on either side of the points where the center lines meet the sides, to mark the corners to be cut away.1 2
Mark a square line with the square tilted
The manual says to place the blade or tongue against the side of the material with the square tilted slightly so the other leg extends across the work, then to mark with pencil or crayon. The same chapter lays out stair cuts by repeating a 9 inch by 12 inch setting on the square.1

History

Earliest documented

ca. 1981–1975 B.C.

Thebes, Egypt (tomb of Meketre)

The Metropolitan Museum of Art holds a wooden carpenter’s square, 15.1 cm long and 11.5 cm wide, from its 1920 excavation of the tomb of Meketre at Thebes, dated to the early reign of Amenemhat I in Dynasty 12.1

The square is among the oldest measuring tools, because joinery depends on right angles. The Met holds a wooden carpenter’s square from the tomb of Meketre at Thebes, of about 1981–1975 B.C., and Late Period Egyptian amulets in the shape of a square. Hodgson, writing in 1903, notes that a square had been found among carpenters’ tools in an Egyptian tomb and rejects on those grounds the Greek claim that the tool was invented by one Theodosius of Samos.

The steel framing square is an American nineteenth-century form. Hodgson describes its predecessor as a clumsy iron square, mostly made in England, with a narrower blade, irregular and often incorrect markings, and used chiefly in blacksmith shops. He dates the first steel squares with a 2-inch blade to the early nineteenth century near New Haven. In Shaftsbury, Vermont, Silas Hawes patented a carpenter’s square, and the Vermont Historical Society holds a square marked “Hawe Patent” with hand-struck numerals, dated 1819–1859, and a later Eagle Square example with mechanically struck graduations.

Its fixed proportions made it a calculator as well as a square. With the blade and tongue graduated in inches, any rise and run can be set out at full size or to scale, and Hill’s 1879 article and Hodgson’s treatise are long collections of such problems for rafters, braces, octagons, stairs and handrails.

The tables moved the arithmetic onto the tool. Howard’s 1881 patent tabulates rafter lengths for whole spans at three common pitches. Nicholls’s 1901 patent arranges figures under each inch mark, so that a carpenter reading under the number for the rise finds the length of common, hip, valley and jack rafters per foot of run. Hodgson’s ABC of the Steel Square reports that the makers of the Nicholls square replaced the board measure with a rule for framing, and his treatise describes a market already supplied with many squares, attachments, charts and keys for finding cuts.

iBerkshires, citing the Bennington Museum and the Shaftsbury Historical Society, reports that the Eagle Square partnership held a monopoly on the square-making business and earned a national reputation, that Stanley bought it out, and that Stanley announced in 2000 the closing of the Shaftsbury plant, ending a tradition of tool-making there of nearly 200 years.

Timeline

ca. 1981–1975 B.C.
A wooden carpenter’s square is placed in the tomb of Meketre at Thebes.1
664–332 BCE
Egyptian amulets of the Late Period take the form of a carpenter’s square; the Met holds a hematite example.1
early 1800s
The first squares made of steel with a 2-inch blade are made near New Haven, Connecticut, as far as Hodgson could discover.1
1817 or 1819
Silas Hawes of Shaftsbury, Vermont, is granted a US patent for a carpenter’s square (see disputed).1 2 3
1819–1859
Squares marked “Hawe Patent / Warranted steel,” with numerals hand-struck in the metal, are made in Shaftsbury.1
1859
Four Shaftsbury makers form the Eagle Square partnership, according to the Bennington Museum’s director of education.1
1859–1900
Eagle Square squares of 24 by 16 inches are graduated with mechanically struck marks.1
1879
William E. Hill describes the “framing square,” its blade and tongue, diagonal scale and roof-framing uses in The Illustrated Wood-Worker.1
1881
Jeremiah G. K. Howard of Montana Territory patents a carpenter’s square bearing a table of rafter lengths for spans at one-fourth, one-third and one-half pitch (US Patent 247,353).1
1901
Moses Nicholls of Glenwood, Iowa, patents a square with rows of rafter figures per foot of run, including hip, valley and jack rafters (US Patent 672,455).1
1903
Fred T. Hodgson publishes A Practical Treatise on the Steel Square, later expanded; its second edition is dated 1909.1
1915 or 1916
The Stanley company acquires the Eagle Square company (see disputed).1 2
2000
Stanley Works announces it will close the Shaftsbury plant, ending nearly two centuries of square-making there, according to iBerkshires.1

Where the sources disagree

When did Silas Hawes patent his square, and what did the patent cover?

1817; Hawes was granted one of the first patents by the US government for his carpenter’s square.1 2
iBerkshires, citing Phyllis Chapman of the Bennington Museum and the Shaftsbury Historical Society
1819; the patent was for tapering the square from the heel to each end to make it lighter, better balanced and less costly in metal.1
Barry’s Big Blog of Building
The Vermont Historical Society dates its “Hawe Patent” square to 1819–1859.1
Vermont Historical Society

Where was the steel square first made?

Near New Haven, Connecticut, early in the nineteenth century; Hodgson reports hearsay of Sheffield-made steel squares 150 years earlier but says he has no reliable evidence for them.1
Fred T. Hodgson (1903)
Shaftsbury, Vermont, is the birthplace of the modern carpenter’s square.1
iBerkshires
A legend of a Vermont blacksmith forge-welding two saw blades after the War of 1812 is apocryphal, and steel squares existed earlier.1
Barry’s Big Blog of Building

When was the Eagle Square company formed, and when did Stanley acquire it?

Four men formed the Eagle Square partnership in 1859; Stanley bought it out in 1915.1 2
iBerkshires, citing the Bennington Museum
Hawes and Stephen Whipple went into business as the Eagle Square Company a year after the patent; Stanley Rule and Level bought a majority interest in 1916.1
Barry’s Big Blog of Building

Gaps in the record (7)

Hawes’s patent was issued before the 1836 Patent Office fire, and its text and drawing have not been read. The 1847 government List of Patents for Inventions (Internet Archive) indexes a patentee Silas Hawes, but the available OCR does not allow the entry’s subject or date to be read.
The DATAMP patent record and the Shaftsbury historical marker could not be fetched from here.
The Met’s Meketre square may be a full-size tool or a model; the record read gives dimensions only.
No Stanley or Eagle Square catalog page has been read for the twentieth-century product line, aluminum squares or the current table layout.
No standard for framing squares has been identified; standards is empty.
No independent accuracy test has been sourced, so buying is null.
No sourced safety entries.