Rule 16 of 31 · Chapter IV — Keep Tools Sharp
A sharp tool is a safe tool
Why this rule exists
This sounds backwards until you've felt it. A dull chisel or plane needs force to cut, and force is where control goes to die: you lean into it, it skips off the wood, and now the edge is heading for your hand with your whole weight behind it. A sharp tool cuts where you aim it with a light push, so it stays predictable. Dull tools don't just work badly, they hurt people. Keep them keen and they obey.
In practice
Learn to sharpen and do it often, before a tool feels dull rather than after it's fighting you. A quick touch-up on a fine stone or a strop takes a minute and keeps an edge singing through the work. Test the sharpness by paring end grain or shaving a thumbnail, and hone the moment cuts get ragged or the tool wants extra muscle. Keep your sharpening kit set up and within reach so a touch-up is never a chore you talk yourself out of.
When it doesn't apply
Sharp doesn't cancel the other safety habits; a keen blade still cuts you if you put a hand in its path or push toward your body. And for demolition, prying, or scraping paint, use a beater tool you don't mind abusing rather than dulling and chipping your good edges on nails and grit.