Starting out with a shaft which is too big is uneconomical (a shaft with an O.D. as large as in (a) requires too much machining). In this case the middle portion could have been left rough. Starting with drawn rod of the right size (b), only the two ends need to be machined; and metal removal is greatly reduced.

Square ends (a) represent a hazard (injury to fingers), are easily, damaged and more difficult to assemble. Although rounding off is better (b), a small chamfer (C) is safest and least expensive.

To protect a conical cavity from damage (a) when machining between centers, a small recess (b) suffices.

Long small diameter bores (a) should be avoided, due to high machining costs and possibility of tool breakage.

Long bores for guiding shafts (a) should be enlarged in the middle section (rough boring suffices), in order to facilitate guiding the shaft and reduce finish machining.

Whenever possible, design for minimum setup time. Design (a) requires two setups (boring from each side), while design (b) requires only one setup (boring from right side only).