I have found that the easiest way to set up a smooth azimuth rotation is to simply bolt a short piece of threaded rod onto a board like in the picture below.
Two nuts are then added to the threaded rod and are left to rotate freely.
Using a table saw, cut a groove into the middle of a short board at the same depth and diameter of the nuts. (Note: The nuts I am using in the picture above aren’t really the best. If possible, it would be better to find some that have a square shape for a tighter fit inside the short board.)
This board, in conjunction with the threaded rod and nuts, is then used to hold the “base” of the heliostat in place while still allowing it to turn freely.
Achieving a smooth altitude rotation is a piece of cake. Just use a couple of hinges.