This article: In the 1970s, the Japanese Antarctic Research Expedition (JARE) group designed several drills using side-mill cutters.  These are toothed gears that are driven from the rotation of the main drill motor via 45° spiral gears; their axis of rotation is horizontal, and they are placed so that the teeth cut four vertical slots in the borehole wall.  Guide fins higher on the sonde travel in these slots and provide the antitorque.  The design was effective at preventing rotation of the sonde, but it proved to be almost impossible to realign the guide fins with the existing slots when tripping in.  Misalignment increased the chance of the drill getting stuck in the borehole; and there was also a risk of ice cuttings from the mill cutters jamming in between the drill and the borehole wall, causing the drill to get stuck.  The system was used again in a drill developed in China in the 1980s and 1990s, but the problems inherent in the design are now considered insuperable and it is no longer in use.The most recent anti-torque system design is the use of U-shaped blades, made of steel and fixed vertically to the sides of the sonde.  Initial implementations ran into problems with thin blades bending too easily, and thick blades providing too much resistance to vertical movement of the sonde, but the final design can generate strong resistance to torque in both firn and ice.Drills may be designed with more than one anti-torque system in order to take advantage of the different performance of the different designs in different kinds of snow and ice.  For example, a drill may have skates to be used in hard firn or ice, but also have a leaf-spring system, which will be more effective in soft firn. contains an answer for the question: What are the initials for the group that designed several drills using side-mill cutters?, what is it ?


JARE