Speed square

A speed square, also called a rafter square, rafter angle square, and triangle square, is a multi-purpose

dimensional lumber

, and as a saw guide for short 45 and 90 degree cuts.

The term "speed square" is a genericised trademark based on those owned by Swanson Tool Company^[1]^[2] which first manufactured and sold the tool.

History

Albert J. Swanson invented the A Speed Square in 1925 as a carpenter's layout tool. He later founded Swanson Tool Company to produce it.^[3] Today, Swanson Tool Company still manufactures and distributes the Speed Square and other carpentry tools from its headquarters in Frankfort, Illinois.

Design

Speed squares are manufactured from a variety of materials such as

HDPE

. They are also made in several sizes, including 7-inch, 8-inch, 25-cm and 12-inch sizes.

Embedded degree gradations on the tool eliminate the need for trigonometric calculations and allow for lines to be more easily made.

The tool is an isosceles right triangle with a ruler on one equal side and a fence on the other. It is marked with the word Pivot at the right angle point and displays Degrees on its hypotenuse, Common and Hip/Val markings on its midsection.

Degree indicates the angle in degrees from 0° to 90°.
Common indicates the rise in inches over a 12 inch run for common rafters from 1 inch to 30 inch.
Hip/Val indicates the rise in inches over a 17 inch run for hip or valley rafters from 1 inch to 30 inch.

Some models have divots for fitting a writing utensil to mark lumber with. Speed squares made by the Swanson Tool Company also have a diamond shape cutout on the ruler side at 3½ inches.

Usage

Among its basic uses are marking common,

stringers

, determining and marking angles, and making square cuts on boards.

Common lines made using a speed square include perpendicular cut marks and Angles definition of an angle for roofs, stairways, and decks.

The tool uses a 0° reference. This means when a board is squared off the tool reads 0°. The angle derived is actually a

ISBN 978-0-7641-3918-5

Differences of Angle Square and Protractor
compare 20° on Protractor and Angle Square

References

^ "Trademark Status & Document Retrieval". United States Patent and Trademark Office. May 19, 2017. Retrieved 2021-05-01. Mark: SPEED SQUARE [...] Goods and Services [...] For: Hand tools, namely, squares [...] Owner name: Swanson Tool Company, Inc.
^ "Trademark Status & Document Retrieval". United States Patent and Trademark Office. May 19, 2017. Retrieved 2021-05-01. Mark: SPEED [...] Goods and Services [...] For: HAND TOOLS, NAMELY; SQUARES [...] Owner name: SWANSON TOOL CO., INC.
^ "History". Swanson Tool Company. n.d. Retrieved 2021-05-01.