Abstract: A cutting tool for forming an opening in an object, such a steel belted tire or the like, is disclosed. The cutting tool is provided with a relatively small number of first helical grooves in its body portion, and a relatively large number of second helical grooves. The first and second sets of grooves are oriented in opposite directions relative to the longitudinal axis of the cutting tool. The tool so constructed is durable and capable of providing quick and clean operation in forming an opening in the said object.