The CLRSRF Command [ML]

This command defines a clearance surface. It is used with the RETRCT command to withdraw the tool tip to the clearance surface. A clearance surface will remain in effect until changed by a new CLRSRF command, or a CLEARP command. This command is valid for lathes and 3-axis+ mills.

There are three possible ways in which CLRSRF can be programmed. The clearance surface can be defined by a point, a plane, or a cylinder.

The first format defines a point with coordinates x,y,z. A symbolic point can generally be used by the APT programmer. When a RETRCT command is encountered, the tool will be retracted along the tool axis to a plane passing through this point and perpendicular to the tool axis.

The second format defines a plane using the canonical form where a,b,c specify the unit vector that is normal to the plane and d is the normal distance from the part coordinate origin to the plane. A symbolic plane can generally be used by the APT programmer. When a RETRCT command is encountered, the tool will be retracted along the tool axis until the tool tip rests on this plane.

The last format defines a cylinder using the canonical form where x,y,z refers to any point in the cylinder axis, i,j,k are the direction cosines of the cylinder axis and r is the radius of the cylinder. A symbolic circle or cylinder can generally be used by the APT programmer. When a RETRCT command is encountered, the tool will be retracted along the tool axis until the tool tip rests on the cylinder.

Note that the CLRSRF command only defines the clearance surface, a RETRCT command is needed to position the tool tip on the defined surface. See “The RETRCT Command” for more information on tool retraction processing.

NOMORE removes the definition of the clearance surface that was defined by CLEARP or CLRSRF commands. It is an error to code RETRCT without a defined clearance surface.