Spi 13-279-5 18 Inch 4 Piece Combination Square Set

Product Description

The SPI 13-279-5 is a 4-piece combination square set built for layout, inspection, and measurement work in machine shops, fabrication environments, and on the job site. The set includes a square head, protractor head, and center head, all designed to mount on an 18-inch hardened steel blade. Graduation markings follow both English and metric scales, with increments as fine as 0.02 inches and 0.5 mm, making it suitable for precision layout tasks. The blade is hardened steel for wear resistance, and the heads are cast iron for dimensional stability. Machinists, toolmakers, and experienced tradespeople are the primary users of this type of set.

This combination square set is used in metalworking and general precision layout applications where multiple head configurations are needed from a single blade. The square head handles 90-degree and 45-degree reference work. The protractor head allows angle measurement across a range of positions. The center head locates the center of round stock. Together, the three heads cover the most common layout and inspection tasks found in production machining, maintenance shops, and fabrication facilities.

Key Features

• 18-inch hardened steel blade with English and metric graduation
• 4-piece set includes square head, protractor head, and center head
• Graduation increments of 0.02 inches, 0.03 inches, 0.5 inches, and 1 mm
• Cast iron head construction for dimensional stability
• Dual-scale graduation supports both inch and millimeter measurement
• Single blade accepts all three heads for versatile layout work

Compatibility

Designed as a standard 18-inch combination square set compatible with typical combination square accessories and replacement heads that fit the same blade standard.

Installation Notes

Combination square sets require no installation but should be stored in a case or protected environment to prevent blade warping and head wear. Before use in precision layout work, verify blade straightness and check head clamping lock for secure seating. Periodic cleaning of the blade groove and head locking mechanism ensures accurate, repeatable positioning over time.