Bad GD&T prints

XxXxXx has done some interesting work with their GD&T process. They don't mark up any kind of a print anymore. Part of the part cad data surface is some wireframe, which outlines all mating surfaces. They issue a single spec for all stampings (GLOBAL GENERIC TOLERANCES FOR SHEET METAL COMPONENTS). They make a 3D PDF file that calls out the functions and sizes of all holes, you reference the specs, you program. Outline surfaces are mating tol, non-outline surface are non-mating tol, 15 different hole type callouts, 4 surface callouts, 5 trim callouts.

Only problem is, you have no way of knowing which of the 5 possible types of trim it is, unless you are an XxXxXx engineer as these are not called out on the PDF, the PDF only shows hole type/size, none of the other 2 possible surfaces are ever called out on the PDF (again, without being an XxXxXx engineer, you don't know).

Everything is called out to A|B|C, but some fixtures will have 'D' nets as well (but only sometimes and only if there are more than 3 "A" nets, but I've seen them with 5 nets, all "A").

Oh, and they do NOT allow MMC for any position callout anymore, haven't for a few years, but you are allowed it for the "B" and "C" locators, but the fixtures are made with RFS pins, so you don't get that either.

So, it was a great start, but kinda not as great on the followup. CAD is always master (except for hole sizes, called out on the PDF), all 'basics' come from the CAD file.

XxXxXx has done some interesting work with their GD&T process. They don't mark up any kind of a print anymore. Part of the part cad data surface is some wireframe, which outlines all mating surfaces. They issue a single spec for all stampings (GLOBAL GENERIC TOLERANCES FOR SHEET METAL COMPONENTS). They make a 3D PDF file that calls out the functions and sizes of all holes, you reference the specs, you program. Outline surfaces are mating tol, non-outline surface are non-mating tol, 15 different hole type callouts, 4 surface callouts, 5 trim callouts.

Only problem is, you have no way of knowing which of the 5 possible types of trim it is, unless you are an XxXxXx engineer as these are not called out on the PDF, the PDF only shows hole type/size, none of the other 2 possible surfaces are ever called out on the PDF (again, without being an XxXxXx engineer, you don't know).

Everything is called out to A|B|C, but some fixtures will have 'D' nets as well (but only sometimes and only if there are more than 3 "A" nets, but I've seen them with 5 nets, all "A").

Oh, and they do NOT allow MMC for any position callout anymore, haven't for a few years, but you are allowed it for the "B" and "C" locators, but the fixtures are made with RFS pins, so you don't get that either.

So, it was a great start, but kinda not as great on the followup. CAD is always master (except for hole sizes, called out on the PDF), all 'basics' come from the CAD file.