Capt T
Here are a couple of thoughts on what you are trying to do.
First, if your cuts are heavy and if the wood is fairly soft and green, the
spur center will start to dig into the wood and fill itself up with fibers
from the wood. If you had the drill on end you would call the spur center a
drill bit. Once it jams with those fibers, nothing will get it to hold. Take
more gentle cuts and make sure your tools are sharp.
Second, I like to use a faceplate where possible, not a chuck. It is a myth
that you can get the piece perfectly centered after putting on a tenon. A
faceplate will give superior hold and can be centered as well as a chuck
with a bit of experience.
I would start between centers and rough shape a vase or hollow form, leaving
a tenon on the bottom large enough for a faceplate. I think you are using a
3/4x16 spindle. There is a very nice 2" faceplate made for the Taig lathe
that is great for this application. It needs to be redrilled to take #14
sheet metal screws but this is easily done.
Take a look at my web site for a few more hints. There is a page on doing
hollow forms that should help.

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God bless and safe turning
Darrell Feltmate
Truro, NS Canada
www.aroundthewoods.com