Method of controlling polishing tool holder, polishing tool holder, and polishing device

A method of controlling a polishing tool holder that includes a machine attachment part, an attachment part to which a polishing tool is attached, a movement mechanism including a drive source configured to move the attachment part in an axial direction of the machine attachment part, and a load detector configured to detect a load exerted on the polishing tool attached to the attachment part,

• the method comprising attaching a polishing tool having a grinding element to the attachment part, connecting the machine attachment part to a spindle of a machine tool and operating the machine tool, monitoring an output from the load detector and calculating an amount of change of the load per unit time while the machine tool moves the polishing tool holder along a predetermined machining path, and performing a projection control operation, the projection control operation comprising driving the drive source based on the load detected by the load detector and the amount of change of the load per unit time, and moving the attachment part to advance or retract the polishing tool,
• wherein when the load detected by the load detector is outside a preset load threshold range and the amount of change of the load per unit time is smaller than a preset amount of change threshold, the projection control operation is performed.