| 摘要 |
<p>A workpiece-holding jig for a lathe comprises: a faceplate (1) provided on the reverse thereof with means for attachment to a lathe shaft and on the face with a central plain bore (2) and three sets of threaded bores (3, 4 and 5) extending outwardly therefrom, the bores in each set being spaced along two lines extending parallel to and equidistantly spaced from a radial line extending from the centre of the faceplate, the radial lines being spaced one from another around the central bore by 120 degrees of arc, each set being spaced from the central bore by a different distance; a first support member (9) having a support plate (9b) presenting a support face extending normally to the faceplate and an attachment plate (9a) extending from said support plate on the opposite side from said support face, the attachment plate having two bores (10) therethrough each alignable with a threaded hole in a respective one of the two lines of any of the three sets, whereby screws passed through the plate and into the threaded bores may secure the first support member with the plane of the support plate thereof extending at right-angles to the radial line of the set; a second support member (15) attachable to the support plate of the first support member and extending at right-angles thereto; clamping means (20) securable to the first support member for clamping a workpiece against said first and second support members; a centralising rod insertable into the central plain bore and shaped such that the portion of the rod projecting from the bore presents a flat face in a plane normal to the faceplate and passing through the axis of the rod, an alignment bore passing through the said portion of the rod normal to the flat face, the axis of the bore intersecting the axis of the rod, the flat face providing a reference face against which slip blocks may be temporarily positioned for locating the support members at a desired radial distance from the centre of the faceplate; and an alignment rod having a shape and size corresponding with that of the alignment bore in the centralising rod so as to be a sliding fit in said bore.</p> |
