Smithy CNC Mills - Manual (Page 94)

If the first move after cutter radius compensation has been turned on is an arc,
the arc which is generated is derived from an auxiliary arc which has its center
at the programmed center point, passes through the programmed end point,
and is tangent to the cutter at its current location. If the auxiliary arc cannot be
constructed, an error is signalled. The generated arc moves the tool so that it
stays tangent to the auxiliary arc throughout the move. This is shown in
Figure 9-1.
Regardless of whether the first move is a straight line or an arc, the Z axis may
also move at the same time. It will move linearly, as it does when cutter radius
compensation is not being used.Rotary axis motions (A, B, and C axes) are
allowed with cutter radius compensation, but using them would be very unusual.
After the entry moves of cutter radius compensation, the interpreter keeps the
tool tangent to the programmed path on the appropriate side. If a convex cor-
SmithyCNC Programmer’s Reference Manual: Tool File & Compensation
SmithyCNC Programmer’s Reference Manual: Tool File and Compensation 9-12
Figure 9-4 First Radius Compensatin Move-Straight
Figure 9-5 First Radius Cutter Radius Compensation Move-Arc