Adjustable pipe center and method

A lathe-center for a workpiece having a hollow and a workpiece-axis, the lathe-center comprising:

• a shaft having a shaft-axis, the shaft configured to releasably couple with a lathe-spindle;
• a center-head fixed to the shaft, the center-head configured to fit within the hollow of the workpiece, the center-head including
• a center-base proximal to and concentric with the shaft, the center-base being circular and having a base-diameter,
• a center-end distal to and concentric with the shaft, the center-end being flat and circular with an end-diameter, the end-diameter being smaller than the base-diameter,
• a conical sidewall extending between the center-base and the center-end,
• a plurality of screw-apertures extending from the center-base to the center-end, wherein each of the plurality of screw-apertures are disposed parallel to the conical sidewall, and
• a plurality of keyways recessed into the conical sidewall;
• a plurality of bearing-fins respectively disposed within the plurality of keyways, the plurality of bearing-fins being able to slide within the plurality of keyways, each of the plurality of bearing-fins having
• a bearing-surface disposed distal to the center-head configured to engage the hollow of the workpiece, the bearing-surface being neither parallel nor normal to the shaft-axis, the bearing-surface having a convex surface-curvature structured and arranged to mate with the hollow of the workpiece,
• a retention-flange distal to the bearing-surface engaging the plurality of keyways, the retention-flange being able to prevent the plurality of bearing-fins from moving radially outward from within the plurality of keyways,
• a concavity disposed within the retention-flange, the concavity being semi-circular, the concavity traversing an entire length of the retention-flange, and
• a fin-threading integrated into the concavity;
• a plurality of adjustment-screws corresponding to the plurality of bearing-fins disposed within the plurality of screw-apertures, the plurality of adjustment-screws protrude from the center-end and are sized to freely turn within the plurality of screw-apertures, the plurality of adjustment-screws being in engagement with the fin-threading of the plurality of bearing-fins such that turning one of the plurality of adjustment-screws causes a corresponding one of the plurality of bearing-fins to slide linearly within the corresponding one of the plurality of keyways, the plurality of adjustment-screws each having a drive-axis, the drive-axis being neither parallel nor normal to a respective bearing-surface of the plurality of bearing-fins in order to enable the bearing-surface of each of the plurality of bearing-fins to function as a translating inclined plane against the hollow of the workpiece, such that the workpiece-axis of the workpiece is displaced laterally relative to the shaft-axis as any one of the plurality of bearing-fins slides linearly within the corresponding one of the plurality of keyways;
• and
• a plurality of screw-retainers corresponding to the plurality of adjustment-screws affixed to the center-base, within a recess thereof, over the plurality of screw-apertures, such that each one of the plurality of screw-retainers covers one each of the plurality of screw-apertures, the plurality of screw-retainers preventing the plurality of adjustment-screws from leaving the plurality of screw-apertures, wherein each of the plurality of screw-retainers comprises a flat plate having a semi-circular relief that engages a respective one of the plurality of adjustment-screws such that an end of each of the plurality of power screws adjustment-screws is exposed;
• wherein the shaft has a machine-taper configured to mate with a machine-tapered chuck;
• wherein the plurality of bearing-fins is constructed from hardened tool-steel;
• wherein the lathe-center further includes a bearing coupling the shaft to the center-head, the bearing enabling the shaft to spin freely relative to the center-head, the bearing being disposed within and concentric to the center-base of the center-head;
• wherein each of the plurality of screw-apertures are non-threaded and cylindrical, the apertures being configured to allow the plurality of adjustment-screws to freely spin within the plurality of screw-apertures;
• wherein each of the plurality of screw-retainers include at least one retainer-aperture and at least one retainer-screw, the at least one retainer-screw being dimensioned to pass through the at least one retainer-aperture into the center-base, such that the plurality of screw-retainers is releasably affixed to the center-head;
• wherein the center-head further includes a plurality of base-apertures disposed within the center-base, the plurality of base-apertures being dimensioned and threaded to releasably accept the at least one retainer-screw;
• wherein each of the at least one retainer-screws has a retainer-screw axis along which the at least one retainer-screws-respectively rotates, the retainer-screw axis being parallel to each of the plurality of adjustment-screws;
• wherein each of the plurality of power screws adjustment-screws may be engaged by a drive tool while being retained by the plurality of screw-retainers, the semi-circular relief being respectively aligned and respectively concentric to the plurality of adjustment-screws.