need to hold a bowl by the edge not a center. Whats a poor turner to do? Well, if you are in the $ you can buy a chuck to handle that BUT for a FEW dollars and some shopping time and then some shop time here is how you can make your own chuck to handle that bowl that needs to have a nice base with no blemishes.
https://www.youtube.com/watch?v=5qopqIb_h-oThe video is just 8 minutes TV time ( much longer real time) and is very plain and easy to follow. The U Tube side bars show some other interesting techniques for rounders.