High velocity, low-friction boring tool

A high speed, low friction, boring tool for boring holes located in any machinable material by a drill jig member, said drill jig member being distinct from and positioned upon said machinable material, said tool comprising:

• an elongated cylindrical shaft member;
• a cutting head interchangeably mounted on said shaft member, said cutting head having variable cutting means to cut holes within a predetermined size range within said machinable material,
• a housing coaxially surrounding a portion of said shaft, said housing and the surface of said shaft cooperating to define a completely enclosed annular bearing chamber,
• a low friction ball bearing member coaxially disposed within said enclosed annular bearing chamber, said low friction ball bearing member engaging said shaft and said housing to permit said shaft to displace rotationally and axially on said low friction ball bearing member;
• said housing member having an axially extending, cylindrical, sheath integral therewith, said sheath being disposed axially on said housing from that portion of said housing defining said enclosed annular bearing chamber, said sheath being sized to engage an aperture in said drill jig, directly, and being axially withdrawable therefrom, to guide said cutting head to said machinable material, said housing having means for bearing on said drill jig said cutting head being maintained at least a predetermined distance from said sheath.