Abstract: A tool holder for holding a replacable tool bit having a body part and a cutting edge, the tool holder having a body provided with first and second clamping members which co-operate, in the use, to clamp the tool bit to the body, the first clamping member having a tool bit engageable portion for engagement with the body part of the bit, a fulcrum portion in engagement with the tool holder body and a load applying portion whereat a load is applied to the first clamping member to cause the member to pivot about the fulcrum and so urge the bit, in use, towards the second clamping member. In one version the tool bit is of polygonal shape in side elevation and has a cutting edge at each corner of the polygon, so that a selected one of the cutting edges may be brought into an operative postiion relative to the tool holder by rotating the bit about the first clamping member so that the selected edge is presented to a work piece for cutting engagement therewith.