Wow, a solid 3.5" shaft? Are you supporting a tank? Mine has a 3/16" wall tube on the outside and a 3/16" wall tube on the inside. Actually I think it's metric.

I was wondering about the bearings myself. I saw one stand that had a worm gear drive to rotate it. I happen to have a worm gear winch laying around and I may see if I can adapt it easily. I think removing that powdercoating and lubing it will make a lot of difference.