Only small cuts can be made and the material must be relatively soft for the grips to cut into the face of the material. This centre is mostly used on woodworking lathes
| Centre Lathe Accessories - Centres |
|
The primary use of a centre is
to ensure concentric work is produced; this allows the
workpiece to be transferred between machining (or
inspection) operations without any loss of accuracy. A part
may be turned in a lathe,
sent off for hardening and tempering and then ground
between centres in
a cylindrical grinder. Centres are fitted in the tailstock to support long workpieces. This is to prevent the workpiece bending away from the cutting action. A centre hole must be drilled before a centre can be used. |
| There are a number of different types of centre, depending on the machining operation: |
| Revolving centre | |
|
A revolving
centre,
also known as a live centre in
some countries, is constructed so that the 60° centre runs
in its own bearings and is used at the non-driven or
tailstock end of a machine. It allows higher turning speeds
without the need for separate lubrication, and also greater
clamping pressures.
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| Dead Centre | |
| A dead centre does not rotate - the work rotates about it. Live centre Rotates while dead centre does not rotate. The dead centre are mostly use in the headstock spindle when turning between centres. A dead centre in the tailstock is normally used for very accurate work. Lubrication must constantly be applied when a dead centre is cued in the tailstock. A typical lubrication is white lead, but is not in use any more as it is poison's. Use a high pressure grease. |
|
| Ball centre | |
| Ball centres are either of the of the dead centre type or revolving centre type. This centre is used when cutting taper with the tailstock set-over method. The standard centre cannot sit squarely in the centre hole when the tailstock is set over. |
|
| Half centre | |
|
Another good use
of a dead centre in the tailstock is with a half (dead)
centre which allows you to face almost to the centre of the
part being faced with the centre providing support.
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|
| Cone (pipe) centre | |
|
The cone centre
is used to support work with large holes on the end, for
example for turning or machining pipes and tubes. They are
not recommended for machining heavy components.
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|
| Driving centre | |
|
Driving centres has a number of
spring loaded grips, which dig into the face of the work.
The centre is inserted in the headstock of the lathe and
drive the work without the need of a dog carrier.
Only small cuts can be made and the material must be relatively soft for the grips to cut into the face of the material. This centre is mostly used on woodworking lathes |
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