Update: Spent 3 hours chasing a 1/8 inch gap on a cabinet door in my garage
I was finishing a face frame for a bathroom vanity two weeks ago in my shop outside Boise. The left door sat proud at the top corner by about 1/8 inch. I checked the hinge screws, the stile for twist, even the floor level. Drove myself nuts shimming and re-shimming. Turned out my 4 foot level had a tiny burr on the edge from when I dropped it last winter. It was throwing off every reading by a hair. Swapped to my old 2 foot level and the gap closed in 10 minutes. How do you all check your levels for accuracy without a granite slab?
Tbh this is exactly why I stopped trusting my long level for finish work. Mine got a ding on the bottom edge and I didn't notice for weeks. I finally checked it by flipping it end for end on a flat table saw top and drawing a line, then checking that both lines matched up. The gap between them told me the bubble was off, and sure enough it was reading a hair high.