Most engineering drawings show dimensions from two perpendicular edges of
the workpiece. These are the two edges that you should “find,” or locate, as
you zero the X- and Y-axis dials.
The goal is to set the X- and Y-axis dials to zero with the centerline of the
spindle directly over the respective edge of the workpiece. Then all
movements of the workpiece relative to the spindle are referenced to these
two edges.
To find the left edge of a workpiece:
1.
Put the solid body of the edge finder in a collet or drill chuck in the mill’s
spindle.
2.
Offset the movable end of the edge finder so that it is not concentric with
the body.
3.
Move the edge finder so that it is clear of the workpiece beyond the left
edge.
4.
Lower the mill’s head so that the smaller diameter section of the movable
end of the edge finder is next to the workpiece.
5.
Turn the mill on and adjust the speed control to about half of full speed in
the low speed range or about one third of full speed in the high speed
range.
With the edge finder spinning, it is obvious that the movable end of the
edge finder is not concentric with the body.
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