The APTC provides a wide-range, twin chucking head for the direct clamping of taps. There is no need for separate collets. An adjustable safety torque clutch helps prevent tap breakage. Radial parallel float compensates for misalignment between hole and tap. Length compensation on compression and tension compensates for the difference between machine feed and tap pitch.

Chucking. High concentricity, firm clamping, safe torque drive and large clamping range. APTC can accommodate standard square-ended taps. The tap is clamped by two adjustable set of jaws. The four jaw set provides positive drive at the tap square. The three jaw set centers the tap perfectly. The two jaw sets move independently of one another, providing proper clamping despite any differential in the relation between the tap round shank and square.

Safety Torque Clutch. The safety clutch is infinitely variable to the required tap size torque by simply adjusting to scale. The safety clutch disengages when the preset torque is exceeded. After disengagement, there is virtually no torque on the tap, minimizing clutch wear. This prevents tool breakage. Blind holes can be bottom tapped under full rotation of the spindle. Reversing the spindle, the clutch re-engages and the tap is automatically withdrawn.

Radial Parallel Float. This ball-bearing float device guarantees threads to exact tolerance. It also protects misaligned taps against side thrust. It automatically centers after every tapping operation.

Length Compensation. Ball-cage length compensation provides smooth axial movement, even in the presence of maximum torque. This free axial movement prevents damage to thread flanks when the feed rate and tap pitch do not match. It also permits cutting small threads on heavy machines. The length compensation positions at zero point and is therefore also suitable for machine feed.