A power tool which includes a housing mounted to be moveable with respect to and spaced from a base (8), said housing including a motor to rotate a shaft which includes, at its free end, a tool holder for a cutting tool, said shaft extending from the housing such that the tool holder is located at or adjacent to the base and said housing is connected to the base by at least one extendable assembly. The power tool can be selectively locatable with a guide plate (4) via retaining means (52). The guide plate (4) includes apertures for the receipt of retaining means (52) to allow the power tool to be engaged therewith and optionally datum tabs (84,86) to contact with the power tool to ensure the accurate location of the power tool with the guide plate (4) when held in position by the retaining means (52). A fence (66) can be engaged with the guide plate (4), said fence preferably including measurement means (68) to allow the distance from the fence (66) to the cutting tool of the power tool to be measured and a measuring location system or trammel can be provided for use in at least two modes, a first mode to measure a first range of circles of relatively small diameter and a second mode to measure a second range of circles of relatively larger diameter.

In a working machine, left and right side walls 5L,5R are erected on a bed 3, a forward/backward saddle 9 is movable in forward/backward directions, left and right sides of the forward/backward saddle 9 are movably supported with the left and right side walls 5L,5R, a forward/backward drive device 13 is arranged on the left and right side walls 5L,5R, to move the forward/backward saddle 9 in the forward/backward directions, a left/right saddle 25 is arranged on the forward/backward saddle 9 and movable in left/right directions, a left/right drive device 45 is arranged on the forward/backward saddle 9 on each of forward/backward sides of the left/right saddle 25, to move the left/right saddle 25 in the left/right directions, an up/down slider 51 is movable up and down and arranged on the left/right saddle 25, a lower portion of the up/down slider 51 is provided with a processing head 62 to which a processing tool 69 for processing a work set on the bed is removably and replaceably attached, and an up/down drive device 57 is arranged on the left-right saddle 25 on each of left and right sides or forward and backward sides of the up/down slider 51, to move the up/down slider up and down. The working machine is provided the left/right drive devices 13 arranged at different levels on the forward and backward sides of the left/right saddle 25.