Tool holder

A tool holder for a rotary tool having an elongated cylindrical shank comprising:

• a body having a cylindrical bore with a predetermined inside diameter;
• an elongated cylindrical insert having a throughbore, said insert having an outer diameter larger than said inside diameter of said body cylindrical bore;
• means for removably and coaxially securing the tool shank to said insert within said insert throughbore;
• wherein the tool includes a non-circular section at its end positioned within said cylindrical throughbore and comprising means within said insert throughbore for engaging said non-circular tool section and preventing rotation of the tool shank relative to said insert;
• wherein said rotation preventing means comprises a boss having a non-circular outer periphery, said boss being axially slidably mounted in a like shaped channel at an inner end of said insert throughbore, said boss having a recess adapted to receive said non-circular end of the tool shank, and means for adjustably positioning said boss in said insert channel;
• and
• wherein said insert channel is internally dreaded and wherein said positioning means comprises an externally threaded fastener dimensioned to threadably engage said internal threads in said channel, and means for securing said fastener to said boss so that said boss is secured against axial movement relative to said fastener and so that said boss is rotatable relative to said fastener.