An adjustable pipe center for a workpiece having a hollow and a workpiece-axis, the adjustable pipe 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 circular and having 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, and
- a plurality of keyways recessed into the conical sidewall;
- a plurality of bearing-fins 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,
- a retention-flange distal to the bearing-surface structured and arranged to engage 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, and
- a fin-threading integrated into the concavity;
- and
- a plurality of power-screws corresponding to the plurality of bearing-fins disposed within the plurality of screw-apertures, the plurality of power-screws being sized to freely turn within the plurality of screw-apertures, the plurality of power-screws being in engagement with the fin-threading of the plurality of bearing-fins when the plurality of power-screws and the plurality of bearing-fins are assembled within the center-head, such that turning one of the plurality of power-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 power-screws each having a drive-axis, the drive-axis being neither parallel nor normal to the 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.
- wherein each of the plurality of screw-apertures are disposed parallel to the conical sidewall;
- 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, the plurality of bearing-fins being configured to act as a plurality of bearing-surfaces against a turning workpiece;
- 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 smooth-walled, the apertures being configured to allow the plurality of power-screws to freely spin within the plurality of screw-apertures;
- wherein the lathe-center further includes a plurality of screw-retainers corresponding to the plurality of power-screws affixed to the center-base 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 power-screws from leaving 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 plurality of power-screws have a power-screw axis along which each of the plurality of power-screws rotates, the power-screw axis being disposed at an angle intermediate to the shaft axis and the bearing-surface, such that rotating one of the plurality of power-screws causes the corresponding bearing-surface to move inwardly and alternatively outwardly against the hollow of the workpiece;
- wherein each of the each of at least one retainer-screws has a retainer-screw axis along which each of the each of at least one retainer-screws rotates, the retainer-screw axis being parallel to each of the plurality of power-screws;
- wherein each of the plurality of screw-retainers further includes a semi-circular relief configured to expose the end of each of the plurality of power-screws, such that each of the plurality of power-screws may be engaged by a drive tool while being retained by the plurality of screw-retainers, the semi-circular relief being alignable and concentric to the plurality of power-screws;
- and
- wherein each of the plurality of keyways further include
- a guideway sized to index the plurality of bearing-fins tangentially about the center-head,
- a bearing-shoulder sized to index the plurality of bearing-fins radially about the center-head, the bearing-shoulder preventing the plurality of bearing-fins from moving in an inwardly radial direction relative to the center-head, the bearing-shoulder being sufficiently displaced from a corresponding one of the plurality of power-screws to prevent compression against the corresponding one of the plurality of power-screws by the workpiece when the workpiece is in contact with the plurality of bearing-fins, and
- a retention-keyway configured to engage the retention-flange of the plurality of bearing-fins, the retention-keyway being sufficiently proximate to the plurality of power-screws to index the fin-threading of the plurality of bearing-fins to the plurality of power-screws.