Trammel Head Beam Compass Set, 57" Diameter Range, Hardened Points and Pencil Holder

When it comes to measuring, marking, or scribing large arcs and circles beyond the reach of a standard compass, nothing beats a beam compass. This precision set includes two movable heads that securely lock in place on 3/8" diameter chrome-plated steel beams using knurled knobs. Each beam features a flat top surface to prevent rotation of the heads once locked.

The set includes two 14-1/2" beams and a connector, allowing you to join them for extended reach. With a single beam, you can scribe or draw arcs up to a 14-3/8" radius (28-3/4" diameter). Combined, the beams allow for a 28-3/4" radius (57-1/2" diameter).

One head features a fine-adjustment mechanism with 1-3/4" of travel, controlled by a knurled adjustment wheel for precise settings. Both heads accept either straight or bent hardened steel tips—two of each are included. A pencil holder is also provided, designed to fit standard 0.300" diameter pencils and secured via hex screw to the end of the beam.