Overcoming the limitations of the 3 axis machine.

Standard desktop routers and milling machines permit cutting in relief but what if you need to machine a an object like the one illustrated - a container for a new magic potion, with the product name boldly embossed? 

A few machines in the desktop arena offer the possibility of adding a 4th axis, allowing the work piece to be rotated as it is cut. (A device similar to the tailstock of a lathe holds the work.) The crossed arrows indicate the movement options for the cutting tool and it becomes obvious that even adding a 4th axis will not allow us to cut an opening into the neck of the container. Specialised large, industrial machines can incorporate a powered knuckle in the Z axis allowing the spindle to be positioned for undercuts and cavities. These are the so-called "5 axis" machines. Update: British company produces a desktop sized 6 axis system!

 There is another way ...

You can slice your 3D model in the software you used to create it (in this case one slice along the longer axis would suffice) machine several pieces, and then assemble them. In the case of more complex models, and those too large for the cutting envelope of the machine, it would be nice if the process could be automated. Millit from Switzerland takes care of this. Just import a solid and set the parameters for the machine you plan to use. Millit slices the model (making allowances for such things as undercuts and material thickness) and allows the placing of pegs and bore holes for accurate final assembly. 

CNC Notes