Most of the times the square has legs of the same length (‘isosceles’), while the tool itself usually has one leg that is longer than the other. Every so often you see this more ‘common’ square on charts and here even in the emblem of the German provincial Grand Lodge Zur Sonne (‘to the sun’).
Here we have another one, the seal of the Symbolische Großloge von Deutschland (‘symbolic grand lodge of Germany’).

Top: emblem from 1741. Designer unknown.
Bottom: emblem of another German Grand Lodge. Year and designer unknown.