Rule 21 of 31 · Chapter V — Joinery and Glue-Ups
Dry-fit before you glue
Why this rule exists
Glue-up is a race against a clock you can't pause. Spread glue, and you've got minutes before it grabs, no time to discover a joint that won't close or a clamp you can't find. A dry run, the whole assembly clamped without glue, shows you every problem while you can still fix it calmly. I've never once regretted a dry-fit, but I've cursed plenty of glue-ups I rushed into. Rehearse it dry and the wet run goes smooth.
In practice
Assemble the entire piece dry, with clamps, before any glue touches the wood. Check that every joint closes fully, that the assembly sits flat and square, and that your clamps and cauls are the right length and reach for the job. Lay everything you'll need out in order, glue, brush, mallet, clamps, rag, so it's all within easy reach when the clock starts. Note the clamp positions, then take it apart and glue up with a clear, rehearsed plan.
When it doesn't apply
A single simple joint you've done a hundred times, like gluing one edge to one edge, rarely needs a rehearsal. The dry-fit earns its keep on complex assemblies with many joints closing at once, where a single stuck part during glue-up can wreck the whole piece before it sets.