In fact, by quickly rubbing one metal block against another, the interface will inevitably become flatter and flatter.
Ma Lin was thinking, if oil was applied and this polishing method was used, would it eventually produce a very flat metal surface.
After actually trying it out, he discovered that polishing a metal plate this way required a huge amount of labor, but it could indeed result in a metal surface that met industrial production standards, and consequently, his planers and table saws all had qualified workbenches. However, he had to keep polishing, continuously observing and improving.
Polishing cylinders and spheres by hand is also truly a task of patience.
As long as you have enough patience, you can polish them by hand.
This way, even the world's earliest machine tools could be hand-polished and assembled by him, and using them, he could produce various mechanically complex machines.
It reminded him of adjusting light paths during school experiments.
