set square
A modified try square having an adjustable head.
It is used by some bookbinders in taking precise
measurements, including marking off the head of
the text block for trimming with the plow or
guillotine, board cutting, cutting of mats, etc.
The critical part of this implement is the sliding
arm (or head), which must move freely but not
wobble.
![[CoOL]](/icons/sm_cool.gif){kind=icon}