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What are the parts of an engineer’s square?

What are the parts of an engineer’s square?

Shop for Engineer’s Squares

Labelled side and profile view of an engineers square, Side face of blade, side face of stock, outer working face of stock, inner working face of stock, groove or relief, inner edge of blade, blade, stock, engineer's square with stock, engineers square without stock, side face of square, thicker blade is needed if there is no stock


The stock of an engineers square is the shorter thicker section of the tool On most engineer’s squares, the stock is the shorter, thicker part of the tool, that allows the engineer’s square to sit unaided on a flat surface with the blade in a vertical position, freeing the user’s hands.

The stock also allows the user to butt the tool up to the edge of a workpiece and use the blade as a guide for marking lines at right angles to the workpiece edge.


Blade of an engineer's square On most engineer’s squares, the blade is the longer, thinner part of the tool. The blade is fitted into the end of the stock with the outer edge of the blade protruding from the end of the stock. On engineer’s squares that do not have a stock, the blade is thicker.

The inner edge of an engineer’s square blade can range in length from 50mm (2″) up to 1000mm (40″).


Groove of an engineer's square The groove or notch is a semi-circle cut out from the stock or blade where the inner edge of the two meet. The groove ensures that no swarf, dirt or grit can get between the engineer’s square and the workpiece at this critical point. By preventing this from occurring, the groove helps to reduce the risk of inaccuracy when checking the workpiece is square.

The groove also helps to prevent measuring the angle of a metal workpiece inaccurately should a burr be present on its edge.

Additional features

Bevelled edges of an engineer's square

Bevelled edges

Bevelled edges are only found on engineer’s squares that do not have a stock.

As the blade of these engineer’s squares is thicker, the bevelled edge helps to reduce the contact patch (area of the workpiece in contact with the tool), thus allowing the user to make a quicker, more accurate visual check of any light between the edge of the workpiece and edge of the blade, so determining if the workpiece is square.

The bevelled edge is the one that is not at right angles to it's adjacent sides A bevelled edge is a face that is angled in comparison to the other sides, instead of being square (at a right angle) to them.
Graduation marks on an engineer's square with a stock

Graduation marks

Graduation marks are marks of measurement, most commonly placed along the blade of an engineer’s square. These allow you to measure the length of the line you wish to place on the workpiece, without the need for a ruler.

Graduation marks are useful as trying to hold an engineer’s square and a ruler accurately in place whilst marking a line on the workpiece can be tricky.

Graduation marks on an engineer's square without a stock Graduation marks are more common on engineer’s squares that don’t have a stock.

They can be either imperial or metric graduations, and some squares may feature imperial graduations on one edge and metric on the other.

Wonkee Donkee I had to go to university to have a graduation, if you just needed marks down your side then any old Zebra could graduate!
The foot or stand on an engineer's square without a stock helps it stand upright freeing the users hands or allowing them to view it from another angle.


The foot or stand, is a feature found on some engineer’s squares that do not have a stock. The foot aids the square in standing upright when checking the squareness of a workpiece.

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