Granite Gang Saw: Abrasive Cutting Rate Lab (2D)

This 2D companion turns the 3D gang-saw scene into a side-view process lab built around real abrasive-machining math. A gang saw does not cut granite with a sharp blade edge: steel blades reciprocate back and forth while a fed slurry of abrasive grit and water does the actual material removal through three-body abrasion, rolling loose grit particles between the blade and the stone. The removal rate here follows the same form as Preston's equation — used across lapping, CMP and abrasive-machining processes — as the product of contact pressure, mean blade sliding speed and a grit-size factor; an Archard-style wear law built from the same pressure-velocity product tracks how fast the blades themselves wear down. Stroke rate and downforce set how hard and how fast the abrasive works, grit size trades cutting speed against blade life and finish quality, and blade spacing sets the resulting slab thickness directly — the same variables a quarry operator tunes on a real gang saw, plus a small, physically real touch: blades nearer the edge of the gang see slightly less downforce than the centre blade because the saw frame sags a little under load, a well-documented effect that shows up here as a visible spread in the per-blade cut-depth graph.