... ,dough and crushing corps for livestock's feed ...etc .2. grindstone specification and each part's introductionmillstone , it is ... 45 meters one minute. Millstone circumference caculation general millstone diamter 2 meterhowever , when donkey pull millstone , the stress points ... caculated by diameter about 4 meeers . Circumference formula C=2∏R get walking path circumfereneC= 12.56 meters millstone ...