Jacobs High Torque/High Precision Model Chuck Jacobs high torque/high precision model chucks are precision tested and certified to 0.0016” T.I.R max at half capacity. For use on CNC machining centers in drilling, boring, counter-boring and milling operations requiring heavy penetration. The Jacobs high torque/high precision model chuck is furnished with a spanner wrench to allow the application of supplementary gripping torque. Light tightening increases gripping torque up to 3 times higher than hand tightening. The Jacobs high torque/high precision model chuck resists tool loosening on high-speed machines.