Rotary encoder

A method of mounting a rotary scale member on a machine part which is configured to rotate about an axis of rotation, the rotary scale member comprising a body on which a series of scale features defining a scale that extends around a scale axis is or can be provided, and at least three radially-compliant flexures spaced around the scale axis, the method comprising:

• i) locating the rotary scale member on the machine part such that the scale axis and axis of rotation are substantially parallel,
• ii) subsequently arranging at least a first radial adjustment device so as to contact both the machine part and the rotary scale member, and manipulating the at least first radial adjustment device so as to radially displace the body of the rotary scale member;
• wherein at least the majority of any radial reaction force, generated as a result of the interaction of at least one of the flexures with a radial stop member against which it is radially pressed, and which is imparted on the at least first radial adjustment device by the rotary scale member in opposition to the radial displacement of the rotary scale member, is directed into, and reacted by, the machine part via the contact between the at least first radial adjustment device and the machine part.