Spi 13-277-9 Combination Square Set 18in 4-piece

Product Description

The SPI 13-277-9 is a 4-piece combination square set built for layout, inspection, and measurement work in trade and industrial settings. The set includes a square head, protractor head, and center head, all compatible with an 18-inch hardened steel blade graduated in 4R style. The 4R graduation delivers four scales: 1/8, 1/16, 1/32, and 1/64 inch markings on opposing faces, giving machinists, pipefitters, fabricators, and tool-and-die professionals precise reference in a single blade. Cast iron heads provide rigidity and resistance to wear under shop conditions.

This combination square set is suited for general layout and angle work in machine shops, fabrication facilities, and on industrial job sites. The square head handles 45-degree and 90-degree layout. The protractor head allows angle measurement across the blade. The center head locates the center of round stock quickly and accurately. All three heads accept the same 18-inch blade, so the set functions as a versatile system rather than a collection of single-purpose tools.

Key Features

• 18-inch hardened steel blade for durability and long-term accuracy
• 4R graduation: 1/8, 1/16, 1/32, and 1/64 inch scales for fine layout work
• Three interchangeable heads: square, protractor, and center
• Cast iron head construction resists wear and maintains squareness under repeated use
• 4-piece configuration covers a broad range of layout and inspection tasks

Compatibility

Designed as a self-contained 4-piece combination square set; all three heads are compatible with the included 18-inch 4R hardened steel blade.

Installation Notes

Combination squares are hand-held layout and inspection tools that require no installation. Store the set away from moisture and cutting fluids to prevent rust on the blade and corrosion on the cast iron heads. Verify blade lock tightness before transferring measurements to avoid blade shift. Periodically check head-to-blade squareness with a known reference surface to confirm accuracy is maintained.