Dormer E500 straight flute taps are the only type of taps that can be used by hand but they may also be used in a machine if required Extremely versatile can tap through or blind holes in most materials When tapping blind holes straight flute taps should be used in sets The three taps which form a set are known by more than one name 1 Taper or First tap 2 Second or Intermediate tap 3 Bottoming third or plug tap Metric coarse straight flute taps Tolerance Class 2 for 6H Fit Surface treatment Bright Material HSS High Speed Steel Chamfer No 12 and 3 Serial no 4 and 5 Flute Geometry Straight Flutes ISO529