Definitions

Base Bottom disk Large Diameter

Top Top disk riding on base

XY X Y Coordinates of target pointy on top

At Angle from top ref to bottom after rotation (not shown )

Tc The center top

Rt The distance from Top center to XY

Kr Constant distance from Center Base to Extruder (Tc @ zero) Must be > than Rt

Bc Base Center

Ab Bottom angle (CCW is positive)

Rt=Sqrt(x^2+y^2)

Ab=SIN^-1(Rt/Kr) If X<0 then Ab=-Ab

A’= SIN^-1(X/Rt) If Y<0 then A’ = -A’

At=A’+Ab

Explanation:

The system is shown where the extruder is hovering over XY= 0,0

Rt is the radius of the tangent Circle.

Rt allows us to calculate the angle Ab to rotate the base (Backwards to get the extruder in position.) CCW is positive.

A’ is the angle the top table would have to be rotated to get the point in position in real space. CW is positive.

At is the angle the top table needs to be rotated relative to the base table. CW is positive