Mandrel

A mandrel, mandril or arbor is a tapered tool against which material can be forged, pressed, stretched or shaped (e.g., a ring mandrel – also called a triblet – used by jewellers to increase the diameter of a wedding ring), or a flanged or tapered or threaded bar that grips a workpiece to be machined in a lathe. A flanged mandrel is a parallel bar of a specific diameter with an integral flange towards one end, and threaded at the opposite end. Work is gripped between the flange and a nut on the thread. A tapered mandrel (often called a plain mandrel) has a taper of approximately 0.005 inches per foot and is designed to hold work by being driven into an accurate hole on the work, gripping the work by friction. A threaded mandrel may have a male or female thread, and work which has an opposing thread is screwed onto the mandrel. On a lathe, mandrels are commonly mounted between centres and driven by a lathe dog (typically flanged or tapered mandrels), but may also be gripped in a chuck (typically threaded mandrels) where the outer face of work is to be machined. Threaded mandrels may also be mounted between centres. In addition to lathes, mandrels, more usually referred to as "arbours", are used to hold buffing wheels, circular saws and sanding discs. Typically, such mandrels consist of a cylinder that is threaded on one end.…

A mandrel, mandril or arbor is a tapered tool against which material can be forged, pressed, stretched or shaped (e.g., a ring mandrel – also called a triblet – used by jewellers to increase the diameter of a wedding ring), or a flanged or tapered or threaded bar that grips a workpiece to be machined in a lathe. A flanged mandrel is a parallel bar of a specific diameter with an integral flange towards one end, and threaded at the opposite end. Work is gripped between the flange and a nut on the thread. A tapered mandrel (often called a plain mandrel) has a taper of approximately 0.005 inches per foot and is designed to hold work by being driven into an accurate hole on the work, gripping the work by friction. A threaded mandrel may have a male or female thread, and work which has an opposing thread is screwed onto the mandrel. On a lathe, mandrels are commonly mounted between centres and driven by a lathe dog (typically flanged or tapered mandrels), but may also be gripped in a chuck (typically threaded mandrels) where the outer face of work is to be machined. Threaded mandrels may also be mounted between centres. In addition to lathes, mandrels, more usually referred to as "arbours", are used to hold buffing wheels, circular saws and sanding discs. Typically, such mandrels consist of a cylinder that is threaded on one end. There are many different types of mandrel for specialised applications. Examples include live chuck mandrels, live bull ring mandrels and dead bull ring mandrels. ==History== Mandrels are not recent inventions. Metal machining utilising the spinning process has been recorded as far back as ancient Egyptian times. In metal spinning, a wood or metal spinning mandrel is used, the form of which corresponds with the internal contour of the part to be produced. This method securely clamps the raw material and allows for accurate machining into the desired final form. Since the material is clamped internally, there is no interference to the operator from the lathe/mandrel assembly during production. The traversing mandrel was introduced around 1700, and instantiated the design of a lathe mandrel able to slide axially in its bearings under the control of the operator, so that components having short lengths of thread could be produced, such as screws. The traversing mandrel was primarily employed by watchmakers and ornamental turners during this era. Eventually the device was superseded by a mandrel-driven device called a leadscrew, which uses a train of gears that can be altered as required for the turning application.

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