Yeah, I've designed a weld that wasn't actually possible to manufacture as well. In my case, the shop just substituted a thinner piece of metal without telling me because the thickness I specified wouldn't weld. It actually failed in the field and broke a very nice piece of test equipment owned by the US Navy. Would have been the end of my career probably if I didn't have a paper trail proving it was the manufacturing team's fuckup. Still taught me an important lesson in the importance of inspection and verification.