When the first real one of anything gets built, somebody measures it against the drawing and writes down every number. That is called a first article, and it is the most boring important hour in the whole job. This is that sheet, shrunk to fit a kitchen table.
One object, five measurements
| What you measured | Your guess | The ruler says | Difference | In? | |
|---|---|---|---|---|---|
| 1 | The longest way across | ||||
| 2 | The widest way across | ||||
| 3 | How tall it stands | ||||
| 4 | Something round, straight across the middle | ||||
| 5 | Your own choice |
Then · Count how many were inside your tolerance. Five out of five means your eye is good or your tolerance is generous, and only one of those is worth having.
Extra · Find two things that are supposed to be identical. Measure both. The gap between them is what the word quality actually means.
On our bench the second column holds the number off the drawing instead of a guess. The airplane has five of its own: length, wingspan, sweep, the fin tip, and whether the wing threads its own hole. Nobody has built one yet, so there are no numbers in that column either. When there are, they go up on the Build Log exactly as measured, including the ones that miss.
That is the end of this one
The word for what you just did is first article.
A first article is the first one ever made, measured against the drawing one dimension at a time, before anybody agrees to make a second. It is the moment a drawing stops being an opinion. You have just run one on something in your house.
Where to go now