SPIRAL POINT is also known as ‘gun nose’ or ‘bull nose’ or chip driver. These taps are dimensionally the same as a hand tap, second lead, but have the cutting face ground back relative to the axis of the tap, for the lead portion.
This gives the flute a better cutting action, requiring less power, and pushes the cut material forward, allowing free flow of coolant along the flutes to the cutting edge.
The flutes are not ground as deeply as for hand taps, giving the tap greater strength. It can therefore be run at higher speeds. Spiral point taps are ideal for machine tapping of through holes, or blind holes where there is enough clearance beyond the threaded portion to accommodate the swarf.
Advantages:
• Thread Chamfer is of 4.5 threads & cutting load is distributed
• Shallow flute depth, hence stronger tap
• Chip clogging is eliminated as the tap pushes the chip forward and thus enhancing tool life.