Why do we want our parts to look good? One answer is that we usually have to sell them, either to an inspector or customer. Parts that have a skillfully made appearance are nearly always more accurate, more consistent and easier to sell than carelessly made parts.

Another reason clean, detailed parts are desirable is because they are easier to measure, inspect and talk about. If someone were to ask "How deep is the slot in that part?" it is easy to say "It's within a couple thousandths of a half inch deep." It's not so easy to explain that for a variety of reasons, you're unable to get consistent readings.

People may argue that appearance shouldn't matter as long as parts are in tolerance. Ragged parts can be difficult to inspect to determine if they are in tolerance.

What constitutes quality part appearance? My concept has evolved over the years.

The following are a list of criteria I use to judge part appearance before I ever put a micrometer or caliper on them.

• Does the finish correspond to the function of the part?

• Are finishes consistent throughout the part?

• Is the part de burred properly?

  Minimum and consistent deburring is functional and looks better than heavily filed edges.

• Is the part covered with chatter marks?

  A little chatter may not be an issue on milled parts and can often be seen in long corners and weak areas. Try to keep chatter to a minimum though or it'll look like...