2020-8-3 · Let''s talk about ratios for a moment. We want to make a full yellow belt of plates. A yellow belt moves 15 items per second. A Stone Furnace can make 0.3125 plates per second. Fifteen divided by 0.3125 is 48 -- thus we need 48 furnaces to make a full belt. Luckily the ratio of ore to plates is 1:1 for iron and copper, so we can plan around one ...