The chain idea is a good one but not the best for accuracy. Accuracy costs money, the more money - the more accurate. If you tightened up the chain to even 750 lbs on each chain, that would be 1500 lbs pull across your table. Is your table capable of that kind of pull, what about warping the table if the pull on each chain is different. Your springs would have to be die springs to get that amount of tension in a small package. You need to keep so many teeth in contact with the chain to avoid jump. To get the required number of teeth in contact you will need idler sprockets on either side of your driven one to help wrap the chain around. With the high chain tension on the idlers/ driven sprockets that will put a lot of tension on the bearings, shafts and mounting plate. More tension= more friction= slower speeds which leads to bigger motors to overcome the slow speed. I don't want to be the bearer of bad news.
If it's not nailed down, it's mine.
If I can pry it loose, it's not nailed down.