In SolidWorks assemblies, mates are the basic units that either make everything work together and function properly, or fill the tree with errors and warning symbols. When properly handled, mates enable your assembly to react predictably to changes in parts exactly the same way that sketch relations drive changes in part features. As a result, mates and sketch relations often have the same function and even the same weaknesses to watch out for.
This chapter goes one step further with mates, by not just simply putting parts together with Coincident and Concentric mates, but also mating parts when tolerances, gaps, and symmetry become issues. You will also learn about the more advanced mate types that may be useful for special situations.
One of the assumptions that I make in this chapter is that assembly mates are not just used for positioning parts, but also for motion. Making motion work takes a little more than just establishing the right spatial relationship between parts; it usually also involves analyzing the open degrees of freedom.
From time to time, I have met users who take a static approach to putting parts together into assemblies, by simply placing parts at the correct X- and Y- coordinates ...