3 Part III Some Practical Advice

Perhaps because the Machinery's handbook [45] has tables for press fits, we are lured into using them. Besides, the geometry is simple, and parts count is minimum. Rather standard, accepted practice, right?

No! Why? Because a press fit is overconstrained. Press fits require tight tolerances, generate uncontrolled friction, and create assembly stress, all of which good designers try to avoid. Furthermore, they are hard to assemble, and disassembly might be impossible.

Think press fits, and most of us think of dowel pins pressing into one or more mating parts. But press fits tempt designers in other geometries as well, all of which are sub-standard design.