To centre a workpiece on a lathe a hole is first drilled at one end of the workpiece and secondly a centre of the lathe is located in the hole so as to rotatably mount the workpiece in the lathe.
Conventionally, the hole is drilled by mounting the workpiece in the lathe and using a Jacob's chuck and a centre drill. However, this is a relatively complicated centering procedure since the Jacob's chuck is first installed in the lathe, the centre hole is then drilled in the workpiece, the Jacob's chuck is then removed, a centre is then installed in the lathe, and finally the centre is engaged with the drilled hole in the workpiece.
To simplify the centering procedure at the lathe, some workshops have a drilling apparatus remote from the lathe to drill the centre hole. However, centering the workpiece on the lathe takes a relatively long time using such drilling apparatus.
It is an object of the invention to provide a centering assembly for a lathe which permits a centre hole to be drilled on the lathe and permits a centre to be located in the drilled hole in an improved, faster and simplified manner.
My invention includes a centering assembly for centering a workpiece in a lathe including a rotatable centre having an opening along the axis of rotation thereof, a drill in said opening, and means for moving the drill along said axis of rotation from a retracted position within the centre to an extended position for drilling said workpiece.
Preferably holding means are provided to prevent rotation of the centre when the drill is moved to the extended position.
Further objects and advantages of the invention will appear from the following description of a preferred embodiment thereof given by way of example with reference to the accompanying drawings.