What is a test grid, and why does everyone insist on it?

A test grid is a small matrix engraved or cut on scrap: speed steps across the columns, power steps down the rows, one square per combination. Ten minutes of scrap turns "what settings for X?" into a circled cell you measured on your machine.

It is the insistence because settings do not transfer cleanly — lens condition, true optical output, air pressure, and material batch all shift the window. Every chart in our settings library ships with a bracketed range for exactly this: the chart gets you close, the grid makes it yours.