Ok, I core everything. I take a rounded bowl blank to the drill press,
and use the proper sized forstner bit to drill a recess, in the
center, about 1/4 to 3/8 inch deep in the top of the blank. I mount
the blank via an expanding chuck (Vicmark), and turn the bottom. I use
a dovetailed scraper to make the recess on the bottom, usually about
3/16 deep, although I never measure. The angle on the dovetail matches
the angle of the jaws on my chuck when the handle and blade and handle
are parallel to the ways, so the angles of the wood and jaws match for
a perfect fit. I do hold the tool so that it just barely touches the
wood on the final cut on the outside of the dovetail. This evens out
that 1/64 of an inch that creates some of the inevitable wobble that
you get when you reverse. When I remove the core, it already has a
centered recess. I finish turn the big bowl, then remount the core.
The chuck never has to come off, and I don't need the tailstock for
stability. Of course, this has taken a few years to work out all the
details, but it works for me.
robo hippy

On Aug 2, 7:59 am, (Arch) wrote:
Hi Mac,

Good tip for when a tail stock interferes with cutting a hole with
straight or angled walls for expansion jaws.

Pickying right along, it dovetails nicely (again misusing the word) into
my cautioning that the bottom of a "Forstner bit straight walled recess"
is not usually truly perpendicular to its walls.

Sorry! It's the heat, not the humididy.

Turn to Safety, Arch
Fortiter

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