2: Lathe Fixtures(Turning fixtures)
The standard work holding devices or fixtures for lathe are:
· Three and four jaw chucks
· Collets
· Face plate
· Mandrels
· Milling vice
If the job can be held easily and quickly in the above mentioned standard devices, then there is no need for special work holding devices. However many jobs particuly casting and forging, because of their shapes, cannot be conveniently held by any of the standard devices. It then becomes necessary to build a special work holding device for the job. Such a device is called lathe fixture.
A lathe fixture consists of a base , location and clamping devices. A lathe fixture can be fixed to the lathe either by holding in the chuck jaws or fixing to a face plate.
Basic Design Principles for Turning or Lathe Fixtures:
1. To avoid vibration while revolving , the fixture should be accurately balanced.
2. There should be no projections of the fixture which may causes injury to the operator.
3. The fixture should be rigid and overhang should be kept minimum possible so that there is no bending action.
4. Clamps used to fix the fixture to the lathe should be designed properly so that they don’t get loosed by centrifugal force.
5. The fixture should be as light weight as possible since it is rotating.
6. The fixture must be small enough so that it can be mounted and revolved without hitting the bed of the lathe.