Manually operated lens cribber

Abstract

A manually operated lens cribber has a cutting compartment on a base. The cutting compartment has a door that is moveable between a closed position and an open position. A cutting tool is inside the cutting compartment and rotates about a first axis. A lens blank carrier is attached to the base in a manner to be manually movable across the base on a second axis that is substantially perpendicular to the first axis. The lens blank carrier has a hand operated screw mechanism on which a lens blank can be mounted and which moves the lens along a third axis that is substantially parallel to the first axis. A releasable end stop is positioned on the base for positioning the lens blank carrier relative to the cutting tool so that the desired amount of material is removed from the lens blank. A calibration and positioning scale is also provided.

We claim: 
     
         1 . A manually operated lens cribber comprising:
 a base;   a cutting compartment on the base, the cutting compartment having a top, side walls and a door attached to the side walls, the door being moveable between a closed position and an open position such that the base, top, sidewalls and door in the closed position define an enclosed cutting chamber;   a cutting device connected to the base and having a cutting tool which is within the cutting chamber and rotates about a first axis;   a lens blank carrier attached to the base in a manner to be manually movable across the base on a second axis that is substantially perpendicular to the first axis, the lens blank carrier having a hand operated screw mechanism on which a lens blank can be mounted, the hand operated screw mechanism having a handle which when turned causes the lens blank to move along a third axis that is substantially parallel to the first axis and wherein movement of the lens blank carrier in one direction along the second axis will move at least one portion of the lens blank carrier into the cutting chamber and movement of the lens blank carrier in an opposite direction along the second axis will move the at least one portion of the lens blank carrier out of the cutting chamber; and   a releasable end stop on the base which is positioned on the first second axis at a location where the lens blank carrier can abut the end stop when moved along the second axis toward the end stop.   
     
     
         2 . The manually operated lens cribber of  claim 1  also comprising a window in the top. 
     
     
         3 . The manually operated lens cribber of  claim 1  wherein the screw mechanism has a rod with threads and a housing that surrounds at least a portion of the rod with threads also comprising a retractable pin connected to the housing and positioned to engage the rod with threads, the retractable pin being moveable between a first position in which the retractable pin engages the threads and a second position in which the retractable pin does not engage the threads. 
     
     
         4 . The manually operated lens cribber of  claim 3  also comprising a spring attached to the retractable pin and the housing which biases the retractable pin toward the first position. 
     
     
         5 . The manually operated lens cribber of  claim 1  also comprising an exhaust pipe which extends from the cutting chamber and is attached to the base. 
     
     
         6 . The manually operated lens cribber of  claim 1  also comprising:
 a rail attached to the base and positioned on the second axis; and 
 a carriage on the rail and attached to the lens blank carrier. 
 
     
     
         7 . The manually operated lens cribber of  claim 1  wherein the end stop has an index line and further comprising a scale on the base and positioned to be adjacent the index line when the end stop is in a selected location. 
     
     
         8 . The manually operated lens cribber of  claim 7  wherein the scale has fixed scale base which has a series of markings that correspond to diameters of cutting tools, and a moveable scale base having markings that correspond to diameters of cribbed lens blocks, at least one set screw connected between the scale base and the scale moveable base for securing the moveable base against movement relative to the fixed scale base.