One of my favorite quotes as it relates to working in a machine shop was spoken by a veteran tool maker I once worked for. It was in response to my complaining about having wasted time working on a part that was already out of tolerance. He said: "All I know is if I don't check it...it's wrong."

It seems you can double check things all day long without finding an error then the first time you don't check something that's the measurement that'll be wrong.

Part of learning any trade is learning how to avoid trouble. Mistakes are no fun. The trick is to try to develop habits and ways of working that reduce your chances of making mistakes without wasting time.

The following is a list of suggestions that may help you stay out of trouble. Everybody is different in how they approach jobs and each of us has our own strengths and weaknesses.

With that in mind, some of the following suggestions should give you some insight into avoiding errors. ...