Turn a piece of stock about 1/4" thick to a size that is just smaller
that the id of the cone, about 1/2" deep in the cone. Center drill it.

Chuck a piece of round stock just the size of the id of the small end
centrally in the headstock chuck.
Slide the small end of the cone over it.

Push the disk into the cone from the big end.
Bring up the tailstock to push on the center drilled hole in the disk.
Check for concentricity. Maybe a tap here or there to true it up.

Where did you get the cone?

Pete Stanaitis
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