ISRO Technician-B Fitter Question Paper - 2017 (Set - 1) with Answer Key

The type of drill used for general purpose drilling work is Type N.

The helix angles vary according to the material being drilled. According to indian standards, three types of drills are used for drilling various materials.
Type N - For normal low carbon steel.
Type H - For hard and tenaceous materials.
Types S - For soft and tough materials.

The angle between the flanks in trapezoidal thread is 30 degree.

The process of enlarging and finishing previously drilled holes to accurate size using a multi-point cutting tool is called as Reaming. The Tool used for this process is called Reamer.

A NO-GO plug gauge is used to check the upper limit of a hole.