The more I think about this the less I understand what is happening, a not
unusual occurence for me. If you are roughing the bowl why are you using a
glue block at all? Either there should be enough scrap at the bottom of the
piece for a faceplate or certainly enough for a spur center. I rough
entirely between centers, exterior and interior. If you are finsihing the
bowl green and letting it warp this is a different matter. In that case I
would rough between centers using a face plate at the base and remove the
tenon with large jaws, a jam chuck or other means, The chances of flight are
minimal to say the least. (The tenon "could" split.) Occasionally I have
turned a hollow form from green wood when the screws for a face plate would
remove too much of the piece. In that case I heat the bottom of the piece
with a heat gun to dry it and use hot glue. I have also used CA with equally
good results.Make sure the surfaces are flat and dry.
--
God bless and safe turning
Darrell Feltmate
Truro, NS Canada
www.aroundthewoods.com