I have had very limited experience using a scroll chuck in the expansion mode, but I hollowed out a vessel this morning that I had this way. About 25% of the way into the hollowing, it dawned on me that I had pretty well finished the foot before I reversed it in the expansion chuck. The thing is, I didn't create a shoulder at the time I turned the foot. For the remainder of the hollowing, I took conservative cuts and was very careful not to hog. I probably checked the snugness of the chuck 30 times. The hollowing went without incident. So did I just get lucky? Should I have turned a shoulder at the foot to be taken off later when I finish the foot?