Diagonal scale: Plain scales cannot be used for taking smaller measurement. The distance between the consecutive divisions on a plain scale, at best can only be 0.5 mm. In other words, the smallest measurement that can be taken. Using a plain scale of RF 1:1 is 0.5 mm. If the RF of a plain scale is 1:5, the smallest measurement such a scale can take is 2.5 mm (0.5 mm x 5).

Distance of centre of one rivet to the centre of next rivet measured parallel to the seam is called pitch.

In Clearance fit, the largest permitted shaft diameter is smaller than the diameter of the smallest hole, so that the shaft can rotate or slide through with different degrees of freedom according to the purpose of mating members.

Hole Basis System In Hole basis system hole limit dimensions are considered constant and various types of fits are obtained by suitably varying the limit dimensions of the shaft.

Shaft Basis System In shaft basis system, the shaft limit dimensions are kept constant and various types of fits are obtained by varying the limit dimensions of hole.