up to the hub
1. The central part, usually cylindrical, of a wheel; the nave. See Illust. of Axle box.
2. The hilt of a weapon.
3. A rough protuberance or projecting obstruction; as, a hub in the road. [U.S.] See Hubby.
4. A goal or mark at which quoits, etc., are cast.
5. Diesinking A hardened, engraved steel punch for impressing a device upon a die, used in coining, etc.
6. A screw hob. See Hob, 3.
7. A block for scotching a wheel.
Hub plank Highway Bridges, a horizontal guard plank along a truss at the height of a wagon-wheel hub.
Up to the hub, as far as possible in embarrassment or difficulty, or in business, like a wheel sunk in mire; deeply involved. [Colloq.]