A square head and steel rule that when used together have both a 45 and 90 face to allow the testing of the accuracy of two surfaces intended to have these angles.

Related Terms


A mass of reinforced concrete cast around the head of a group of piles to ensure that they act as a unit to support the imposed load.


[DESENG] Ahammerwithapoint at one end of the head and a blunt surface at the other end.


A screw having in its head a recess in the shape of a cross; it is inserted or removed with a Phillips screwdriver that automatically centers itself in the screw.


The end of a hammer head with a hemispherical, wedge, or other shape; used to bend, indent, or cut.


A bolt with a head resembling an upside-down pan.


A die head for cutting screws that opens automatically to release the cut thread.


1. A condition existing when the drive rod of the drill swivel head is not centered and parallel with the borehole being drilled. 2. A borehole that has deviated from its intended course. 3. A condition existing wherein any linear excavation (shaft, drift, borehole) deviates from a previously determined or intended survey line or course. 4. State in which an equipment or subsystem is in standby, maintenance, or mode of operation other than online.


1. A frame used in front of a television picture tube to conceal the rounded edges of the screen. 2. A thin sheet of metal or other material containing an open pattern, used to shield selected portions of a semiconductor or other surface during a deposition process. 3. A protective covering for the face or head in the form of a wire screen, a metal shield, or a respirator.


[DESENG] Ablunt-endedscrew with a standardized thread and a head that may be flat, round, fillister, or oval, and may be slotted, or constructed for wrenching; used to fasten machine parts together.


A heavy-weight bolt with a square, hexagonal, or flat head used in the automotive, aircraft, and machinery fields.

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