Westcott AT-8 8" Adjustable Triangle Scale Drafting Tool

The Westcott AT-8 is an 8-inch adjustable drafting triangle that sets any angle between 0° and 90° using a rotating pivot arm calibrated against a graduated arc scale. What distinguishes it from a standard 45° or 30/60/90 fixed triangle is that it eliminates the need to own multiple triangles for angle variety — one tool covers the full right-angle range. The dual graduation system is a practical time-saver: inner arc markings show the direct angle, while the outer arc simultaneously displays the complementary value, so a drafter working with paired angles never has to calculate the difference manually. The translucent plastic body keeps the underlying artwork or engineering drawing visible through the tool, which reduces the parallax errors that come with opaque straightedges.

Four circular openings — 1/4, 1/2, 3/4, and 1 inch in diameter — add a circle-tracing function that makes the AT-8 useful for geometry students, architects sketching plan details, and illustrators roughing in circular elements quickly. The tool is explicitly designed for both classroom and professional drafting environments: light enough for a student's pencil case, functional enough for architectural and engineering layout work. Construction is plastic throughout, which keeps weight minimal but means long-term precision depends on protecting the pivot and edges from physical damage. For users who want a single adjustable triangle with built-in small-circle capability, the AT-8 offers that combination in an 8-inch form factor.