A method for the in-situ reconditioning of a heavy piece mounted on a floor, comprising: assembling a jig mounted on said floor to be placed in the vicinity of the piece to be reconditioned also mounted on said floor, said jig supporting a frame on which is mounted a precision robotic arm carrying at least one machining unit; aligning said piece and said jig with a precision alignment tool to allow said jig, said frame and said robotic arm to form a precision machining apparatus; and machining said piece using said precision machining apparatus, the method being characterized in that: prior to said assembling, positioning stilts on the floor using a precision laser alignment tool and adjusting height of said stilts using a precision laser alignment tool, said stilts positioned to receive said piece and said jig; said alignment of said piece and said jig being made using a precision laser alignment tool; and said assembly of said jig is performed such that said jig is arranged around said piece to be reconditioned, said frame comprising a gantry, and said jig pressing said gantry at both ends, said jig being configured such that a portion of said jig moves relative to said floor, said reconditioning comprising moving said portion of said jig relative to said floor, said jig comprising a central stilt and an annular turntable centered around said center stilt, said assembling step comprising placing said piece around said central stilt, and said gantry being pressed at one of said two ends on said central stilt and at the other of its said two ends on said turntable. assembling a jig mounted on said floor to be placed in the vicinity of the piece to be reconditioned also mounted on said floor, said jig supporting a frame on which is mounted a precision robotic arm carrying at least one machining unit; aligning said piece and said jig with a precision alignment tool to allow said jig, said frame and said robotic arm to form a precision machining apparatus; and machining said piece using said precision machining apparatus, the method being characterized in that: prior to said assembling, positioning stilts on the floor using a precision laser alignment tool and adjusting height of said stilts using a precision laser alignment tool, said stilts positioned to receive said piece and said jig; said alignment of said piece and said jig being made using a precision laser alignment tool; and said assembly of said jig is performed such that said jig is arranged around said piece to be reconditioned, said frame comprising a gantry, and said jig pressing said gantry at both ends, said jig being configured such that a portion of said jig moves relative to said floor, said reconditioning comprising moving said portion of said jig relative to said floor, said jig comprising a central stilt and an annular turntable centered around said center stilt, said assembling step comprising placing said piece around said central stilt, and said gantry being pressed at one of said two ends on said central stilt and at the other of its said two ends on said turntable. prior to said assembling, positioning stilts on the floor using a precision laser alignment tool and adjusting height of said stilts using a precision laser alignment tool, said stilts positioned to receive said piece and said jig; said alignment of said piece and said jig being made using a precision laser alignment tool; and said assembly of said jig is performed such that said jig is arranged around said piece to be reconditioned, said frame comprising a gantry, and said jig pressing said gantry at both ends, said jig being configured such that a portion of said jig moves relative to said floor, said reconditioning comprising moving said portion of said jig relative to said floor, said jig comprising a central stilt and an annular turntable centered around said center stilt, said assembling step comprising placing said piece around said central stilt, and said gantry being pressed at one of said two ends on said central stilt and at the other of its said two ends on said turntable.