Combination Squares have a black wrinkle finish on machined cast-iron heads. Used for joint layout, machine set-up, determining level/plumb, or as a depth, height, or marking gauge, they have accurately machined components, steel scribing pins, and built-in levels in the protractor and square heads.
The 6" square/miter fits comfortably in your apron pocket. It measures up to 5" from the square face. Its rule is 0.080" thick by 3/4" wide and graduated in 8ths, 16ths, 32nds and 64ths. For larger layout work, the full-size 12" model includes a 1/10" thick, reversible 12" etched steel rule (same graduations as the 6" size). The blade is square to the head within ±0.001" for the 6" model and ±0.002" for the 12" size; the 45° measurement is accurate within ±0.004" per foot on both. The rules are straight and parallel within 0.001" per foot.
The four-piece combination set includes the 12" square/miter and rule, the bevel protractor and the center-finding head. An 18" rule (same graduations as the 12" Imperial) is offered separately. The optional 12" (30cm) Imperial/metric rule is graduated in 64ths and millimetres on one side, and 32nds and 1/2 millimetres on the other.
A surface gage is a measuring tool used to transfer measurements to work by scribing a line, and to indicate the accuracy or parallelism of surfaces. The surface gage consists of a base with an adjustable spindle (1) to which may be clamped a scriber or an indicator (2). Surface gages are made in several sizes and are classified by the length of the spindle. The smallest spindle is 4 inches long, the average 9 to 12 inches, and the largest 18 inches. The scriber is fastened to the spindle with a clamp. The bottom and the front end of the base of the surface gage have deep V-grooves. The grooves allow the gage to measure from a cylindrical surface. The base has two gage pins (3). They are used against the edge of a surface plate or slot to prevent movement or slippage.