When confronted with a new workpiece many programmers and machinists first consideration is “How will I hold this part?” It is a very important decision to be made, but when it comes to multiaxis machining it should not be the starting point.
Building a good fixture is an expensive part of multiaxis machining. Keep fixture costs down by generating the toolpaths first, then run the program on a virtual machine simulation while ‘levitating’ the part in mid-air. You will be able to place the part in multiple orientations and positions while observing the machine’s motions. This will enable you to find the machines ‘sweet-spot’ – the envelope where the machine executes optimum, smooth, synchronized motion without hitting or even coming close to rotary or linear travel limits. Fixture design should begin at this point since now you can design and build the fixture with confidence, knowing that there will be no need for expensive and time-consuming changes.