Spi 13-456-9 Combination Square Blade 18 Inch 4R

Product Description

The SPI 13-456-9 is an 18-inch replacement blade for combination squares, graduated in the 4R system with four graduations: 1/64, 1/32, 1/16, and 1/8 inch. The blade is finished with a baked enamel coating that protects the graduated markings from wear, corrosion, and shop-floor abrasion. This blade is used to restore or replace a worn combination square blade without replacing the entire tool. Machinists, pipefitters, tool and die workers, and general trade professionals rely on 4R-graduated blades for precise layout work on metal, wood, and composite materials.

This blade fits standard combination square heads that accept an 18-inch blade. It is suited for use in machine shops, fabrication shops, plumbing layout, electrical rough-in, and any trade application requiring accurate scribing, squaring, or depth measurement. The 4R graduation system provides four scales on a single blade, reducing the need to switch tools during layout. Installation or replacement requires no special tools and takes only a few seconds once the locking screw on the square head is loosened.

Key Features

• 18-inch blade length provides extended reach for larger workpieces and layout tasks
• 4R graduation system includes 1/64, 1/32, 1/16, and 1/8 inch scales on one blade
• Baked enamel finish protects graduation markings from wear and corrosion
• Sold individually as a direct replacement blade for combination square sets
• Compatible with standard combination square heads accepting an 18-inch blade

Compatibility

Designed as an OEM-style replacement blade for combination squares that accept an 18-inch, 4R-graduated blade. No specific compatible head models or part numbers were provided in the product data.

Installation Notes

Replacement is performed by loosening the locking screw or clamp knob on the combination square head, sliding out the worn blade, and inserting the new blade to the desired depth before retightening. No special tools are required beyond what is used to operate the square head's locking mechanism. Inspect the head's groove and locking mechanism for wear before installing a new blade to ensure accurate seating and reliable clamping.