Ok, this is one of the simple things has probably been beat to death before (like verifying tape measures), but a search of the forums didn't turn up anything on how to calibrate or verify screw pitch gages. Any ideas? My first thought is to slap it on an optical comparator and compare with an overlay- but where do I get do thread pitch overlays (or do they even exist? Off topic somewhat- How do I create overlays?) If not with an optical comparator, how else?