Spiral point taps

Spiral point taps, often referred to as gun-nosed taps, have an angle ground on the inside of the flute, to push the metal cuttings (or swarf) forwards down the hole ahead of the cutting edges and are recommended for through holes. 

Several suppliers design taps with greater clearance especially for titanium. Spiral-point interrupted-flute taps with alternate teeth omitted have given good results at slow speeds. Modification of the tap by grinding away the trailing edge of the thread is beneficial (see Fig. 6). Typical chamfer relief is 12°. 

Procedure. A stout-necked, round-bottomed flask of about 300 c.c. capacity is closed by a rubber stopper through which pass (1) a tapped funnel, (2) a glass tube drawn out to a point and reaching almost to the bottom of the flask and (3) a glass tube connected with a vertical spiral condenser. The end of the condenser is tightly connected with either a bulbed tube of about 75 c.c. capacity or other absorption apparatus. 

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