89mm stepped 3 wings Drag Drill Bit 3 1/2 inch for drill pipe 76mm
drag bit is a drill bit usually designed for use in soft formations such as sand, clay, or some soft rock. However, they will not work well in coarse gravel or hard rock formations. Uses include drilling water wells, mining, geothermal, environmental and exploration drilling. Whenever possible, they should be used to drill pilot holes because they produce cuttings that are easiest to log.
Step type bits are the most common type of drag bit used in the world today. They are primarily designed for soft to medium formations.
Chevron bits are designed for medium to hard formations and are used in areas that contain a lot of rock and also in the oilfield for drilling out concrete casings and plugs.