Photo by WARDJet, available under CC BY SA 3.0 US
As desktop manufacturing tools like a CNC, 3D Printer or laser cutter become more common, we find ourselves running into the limitations of the machines that just a few years ago seemed limitless. Traditional CNC and 3D printers work from the top down or bottom up of an XY surface and move up along the Z axis.
This works well for many things but what if we want to work on the underside of a part? Normally, this is done by adding a fourth axis, called an A axis that rotates the part around the center of the X axis, like so:
With access to the sides and bottom, we can make many more parts! But there is still more we can do. By adding rotation around the Y axis (which we will call our B axis), we now have access to almost every bit of our part to be milled.
Shapes which could not have been made by three axis milling are now possible, and milling time is usually lower because you don’t have to remove and remount the buck.
By Andy Hasara