Instrumented cutter

A downhole cutting tool, comprising:

• a tool body defining at least one pocket having an open leading end;
• a cutter in the pocket and attached to the tool body, the cutter having:
• a cutter body with an outer end portion exposed at the open leading end of the pocket, the pocket dimensions permitting at least some transverse movement of the outer end portion;
• and
• a connecting section connecting the cutter to the tool body, the connecting section having a different cross-sectional area when compared to a cross-sectional area of the outer end portion and exhibiting greater compliance than the outer end portion, the pocket surrounding the connecting section and providing higher resistance to transverse movement of the connecting section as compared to the outer end portion;
• and
• a plurality of strain gauges coupled to a carrier wrapped around an inner surface of the connecting section, the plurality of strain gauges including at least:
• at least four chevron gauges connected in a Wheatstone bridge sensitive to shear force on the cutter and insensitive to axial loading and temperature changes of the cutter, each of the at least four chevron gauges including a first gauge with a conductive path at 45° to an axis of the cutter and a second gauge with a conductive path orthogonal to that of the corresponding first gauge;
• and
• at least four Poisson gauges connected in a Wheatstone bridge sensitive to axial force on the cutter and insensitive to shear loading and temperature changes of the cutter, the at least four Poisson gauges not being connected to any of the at least four chevron gauges, each of the at least four Poisson gauges including a first gauge with a conductive path parallel to the axis of the cutter and a second gauge perpendicular to the axis of the cutter.