yes it needs to be below the top. what motor did he use? also for the changeer you dont want aluminum agnist alumin spining.it needs some brass incerts and some moly greessee,possiably the molly greese will do on the wheel&guide.or make the wheel out of brass or steel and use moly lube..you could also add a oil dripercup and posibly a wick so it dont just run off.you could also use a bearing there insted of the disc...lots of ways to skin cats and not get bitten... the price of power feeds has come down a lot in the past 5 years. but most take away some travell.on my big mill(9x42) I made spacers to space it away so I didnt loose somuch, also it was skeey close to the glass DRO scale... Im not sure why they make them like that but thats how they are. I have a 40 year old enco mill drill I may put power drive on...or cnc conversion. this may help if I only add a power feed. thanks and keep the chips flying!!