The buildcraft lumberjack robot won't pick up the end-forged axe. I have double checked that it still accepts vanilla axes, and I don't see a way in the buildcraft configs to add an acceptable axe.

I'm no modder, but I think I've found the corresponding line in Buildcraft's code that checks if an item is an axe: https://github.com/BuildCraft/BuildCraft/blob/e06e7c79511ab89a4eb66799c4f59227c8b76829/common/buildcraft/robotics/boards/BoardRobotLumberjack.java#L33

Probably because it's unbreakable...might have a look into this, but it's not a priority