The watermelon-shaped FA cutter is used for calibrating slots in casing. It is used to provide free passage of the rock breaking tool (bit). The dimensions of cut holes correspond to the nominal diameter of FA.
Options of using the watermelon cutter:
separately, with supply of flushing-cooling liquid through a nipple hole or coupling
together with window and other watermelon cutters - flushing and cooling is carried out through the window cutter system
together with the rock breaking tool and flushing through its flushing system
together with the starter cutter, which is used to cut a window in the well casing.
FAs are custom made with socket and nipple threads.