Abstract
The eguation of the locus of the knife ebge of rotary lathe is usualy considered as follow
γ=α(θ+C) [known as Archimedes Spiral.].
This is true when the knife edge moves exactry to the center.
But usualy the course of the knife edge is lower (or higher) than the horizontal center line a liltle [a].
So there is some difference between the curve which is usualy used and the real one.
The equation of the real curve traced by the knife edge, when the edge moves on the line which does not pass through the center, is follow
θ=√γ2-α2/ma-tan-1√γ2-α2/a+C
a Distance between the course of knife edge and horizontal center line.
m Rate of the velocity of the knife edge.
c Constant, concerned fo the starting point.
