Hi Leo (the other one) :-))
First off, I use the woodworm on wet wood, not hard dry wood (normally) and my drill press only handles 14"D or less, so anything larger than
14" I drill with a handheld drill and eyeball it, and drill deep enough to not bottom out, 1" for the short screw and 1 1/2" for the long one.
I never have a problem just spinning the wood onto the woodworm screw until the face seats against the chuck jaws, and my wood blanks faces are mostly chain sawed and rough, the wood gives enough for the screw to align in the wood in my experience.
I do on occasion back the wood off to insert a wood wedge between the jaw and the wood to have the outside edge of the blank get into plane better.
I also use the largest jaws that I have, gives more leverage and also more face contact and steadiness.
Wobble does not come from the screw being off a few degrees, but from the blanks face not contacting the chucks jaws.
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Have fun and take care Leo Van Der Loo