Ball Bearing

For Danish grain mills, the numbers 300, 400, and 500 do not represent the size of the bearing itself, but rather the diameter of the millstone (grinding stone) or the mill’s width in millimeters (i.e., a 30 cm, 40 cm, and 50 cm mill). Based on the standard dimensions of the rotating shaft (main shaft) in Danish mills commonly found on the market, here are the corresponding bearing sizes for each mill size: 300 mill (30 cm millstone): Standard bearing number: 6206 or 6306 (depending on the year of manufacture and motor power). Bearing dimensions for 6306: Inner diameter 30 mm, outer diameter 72 mm, thickness 19 mm. 400 mill (40 cm millstone): Standard bearing number: 6307 or 6308. Bearing dimensions for 6308: Inner diameter 40 mm, outer diameter 90 mm, thickness 23 mm. 500 size grinder (50 cm stone). Standard bearing number: 6309 or 6310 (withstands very heavy loads). Bearing dimensions 6310: inner diameter 50 mm, outer diameter 110 mm, thickness 27 mm.