The pre-castellated PC boards arrived from OSH Park yesterday. The router paths that Stephen added look to be spot-on, and the router actually seems to have cut them darn near perfectly. The path went right outside the silk-screened grinding guides (that show how far the non-castellated boards should be sanded/ground) and left just a tiny bit of excess to be sanded. OSH Park’s milling tolerance is 5mil so there’s a but of variance across the three boards that I received, but all of them look usable. And they’ve got a special Halloween sticker, too.
I broke out my USB microscope to get a few pictures of the edges as they came from the factory. The first one shows a tab of fiberglass that didn’t get trimmed or cut, as well as a small copper tab inside the via. These get folded over into the castellation in just about every hole.
After cleaning up one of them with a pocket knife, the result is pretty good, even with no grinding or sanding yet.
Overall I’m really pleased with how these boards came out from the factory. Here’s the underside. You can see a bit of tab as well as lots more copper to clean up. Hopefully I’ll get a chance to assemble and test these boards in the next couple days.