TTC 61/64' x 1/2' Shank Ground HSS Silver & Deming Drill: Reduced Shank Drill Bits: Industrial & Scientific. TTC 61/64" x 1/2" Shank Ground HSS Silver & Deming Drill: Reduced Shank Drill Bits: Industrial & Scientific. Standard spiral, helical flutes. . All drills have reduced shanks that are 1/2" in diameter. . Special care should be exercised when using these drills to avoid bending or shearing the reduced diameter drill shank. Can be used in electric drills and drill presses with 1/2" capacity drill chuck. Primarily designed as tools for drilling larger holes with reduced diameter straight shank drills. For most drilling operations in a wide array of materials having low and medium tensile strength ratings. Intended for those applications where only a 1/2" chuck is available to drive the drills. May be used with a wide range of portable or stationary machine tools and with hand held manual drills. For optimal performance and the best tool life suitable, lubricating/cutting oils or the appropriate coolant fluids are recommended. . . .