The retired carpenter next door in Toledo taught me the pencil trick that ended my crooked shelf problem
I was building floating shelves in my hallway last month and every single one came out sloped. I mean visibly sloped, like 3/4 of an inch off over 4 feet of length, and I had already patched and repainted the wall twice trying to fix it. My next door neighbor Gene, who did finish carpentry for 38 years, wandered over while I was cussing at my level and asked to see my tape measure. He didn't say a word about my shelves, he just pulled a stub of a carpenter pencil out of his pocket, rubbed the lead flat on a scrap of sandpaper, and drew a line down my plywood. Then he said "now run your thumbnail in that groove before you cut anything" and walked back home. I tried it on my next board and the saw followed that little channel like it was on rails, dead straight, first try. Turns out the pencil was dull and fat so it was riding up on the wood grain the whole time. I had been measuring right and marking wrong for 6 whole shelves. Anyone else ever have a tiny tool habit like that fix a problem you blamed on your own hands?