I have recently aquired a Tadco Autogard 250 tapping device with a No2 Morse Taper shank. Before I bust any taps can anybody tell me how they work. Does thisdevice slip when a suitable torque is reached for a particular tap. The end of the thing rotates and screws in and there is a scale which has numbers that do not relate to any thing obvious. Sadly there was no instruction book.