nose to the grindstone
Users lay on (often strapped to) a plank above the grindstone. First attested 1532, from John Frith's A Mirror to know Thyself: "This Text holdeth their noses so hard to the grindstone, that it clean disfigureth their faces."
- (idiomatic, after keep, put, have, hold (one's)) used to form idioms meaning "to work hard, or focus heavily on work."
- If he'd keep his nose to the grindstone a bit more, he could be a pretty good student.
- ^ The meaning and origin of the expression: Keep your nose to the grindstone, the Phrase Finder