QuickCAM PRO Model Boundary

[GGS_harrise]

Hi there,

When I am importing an STL into QuickCAM PRO why is the model boundary always a rectangle around the model and not just follow the actual boundary of the shape?
A lot of wasted material and machining time.

Any advice would be greatly appreciated.

(in this specific example the billet of wood I will be CNCing is not actually a rectangle but a triangle which my model should fit onto, but with the unnecessary extra milling the tool runs foul of the workholding screws.)