to glue up rings or segment, the faces being glued should be flat as possible. And a far amount of glue is needed. In the few segments I have done, I used a hose clamp to hold everything together for each ring created, and let it set for a few days. Then sand the faces flat prior to gluing the rings together, a disk sander works well for this. You can use the pressure of the lathe to hold the rings in place as the glue dries. Again, I wait a few days to allow the glue to cure. Hope that helps Ryan