W. E. Dalby 



45 



this path twice full size. The curve is the profile of a section taken 

 through the roller path at right angles to the plane of reference. 



The process of drawing a family of curves is similar. The datum 

 lines are first drawn one for each position of the guide frame in its 



Fig. 



notches. Then the point Z is selected. Guide frame and stock are 

 adjusted to bring the roller over the selected point and then the roller 

 is lowered into contact with the surface and the roller post is securely 



