TrySquare The Trysquare is a Prescision instrument Which is used to check squareness (angle of 90 °) of a surface . The accuracy of measurement by a try square is about 0.002mm per 10mm length , which is accurate enough for most workshop purposes . The try square has a blade with parallel surfaces . The blade is fixed to the stock at 90° . Uses - -The try square is used to check the squareness of machined or filled surfaces . -Check the flatness of surfaces . - Mark lines at 90 ° to the edges of workpieces . (Trysquare made of hardened steel ) -try squares are specified according to the lengths of the blade ie.100mm ,150mm ,200mm .