Matched pairs of square, hardened blocks ground to 1 by 2 by 3 inches, usually drilled and tapped so they can be bolted together or to parts. They raise work, square it to the table, set heights, act as angle plates and stand in as quick fixtures. Because every face is ground square to the others, they double as a reference for checking setups.
Heard on the job
Stand the plate up against a 1-2-3 block and clamp it, that's square enough for drilling the end holes.
Also heard as
- 123 blocks
- one-two-three blocks
Related terms
Parallels
Matched pairs of ground steel bars used to raise a part in the vise to a known, level height.
Fixturing
The design and use of fixtures that locate and clamp parts the same way every time.
Surface plate
A thick slab of granite or cast iron, lapped flat, that every height check and layout line is measured from.