Draft:1-2-3 blocks

1-2-3 inch Blocks are steel blocks used for setup primarily in Milling (machining). The original dimensions are 1" thick, 2" on the shorter side and 3" on the long side. They are accurately machined and ground on all sides. They may be used like Parallels (engineering) and also used for setup, they are through drilled and usually half the holes are threaded, allowing them to be used in combination.

The Metric equivalent is 25-50-75mm.

=Usage= 1-2-3 blocks are primarily used for workpiece setup, usually on a mill, and may also be used for dimensioning. They are not as accurate as Gauge Blocks.