There is provided a guide dresser for milling a saw guide, the guide dresser comprising first and second cutter assemblies that are slidably mounted on a rail or slide system so as to be adjustable, in operation, between an open position and a closed position. There is also provided cutter heads and methods for milling a saw guide.

A sensorless method for cutting tool health monitoring which continuously evaluates the health of a cutting tool and requires no sensors to be added to the machine tool. During a machine tool cutting operation, time series data for one or more machine tool parameter such as spindle torque or servo motor velocity is collected and converted to the frequency domain. The magnitude of the data at the spindle frequency is divided by the magnitude of a reference data set for the same parameter at the spindle frequency, where the ratio is designated as a tool breakage indicator. The tool breakage indicator is monitored over time to identify any increase in value, and its value is also compared to predefined thresholds. Various criteria may be defined which trigger the replacement of the cutting tool based on the value and/or the rate of change of the value of the tool breakage indicator.