Powermatic 3520C Operating Instructions And Parts Manual page 22

7. As the bowl takes shape, work on the bottom
(tailstock end) to accomodate attaching a face
plate.
8. Turn a short tenon (about 1/8" long) the size of
the hole in the faceplate. See Figure 10-10. This
will allow centering the workpiece when the
faceplate is attached.
Figure 10-10
9. (NOTE: If you plan to use a chuck, turn a tenon
of the appropriate length and diameter to fit your
chuck.)
10. Stop the lathe, remove workpiece and attach
face plate or chuck (see sect. 10.4.1, Mounting
Stock).
The surfaces of faceplate and
workpiece should mount flush to each other.
11. Finish turning the outside of bowl with 1/2" or
3/8" bowl gouge. Leave additional material at
base of bowl for support while turning interior.
This will be removed later.
To Shape Interior of Bowl:
1. Stop the lathe and move tailstock away. (You
may want to remove the center from the
tailstock to avoid bumping it with your elbow.)
2. Adjust tool support in front of the bowl just below
centerline, at a right angle to the lathe ways.
3. Rotate workpiece by hand to check clearance.
4. Face off top of bowl by making a light shearing
cut across the top of workpiece, from rim to
center.
5. Place 1/2" bowl gouge on tool support at center
of the workpiece with the flute facing top of
bowl. The tool handle should be level and
pointed toward the four o'clock position, as
shown in Figure 10-11.
6. Use the left hand to control cutting edge of
gouge, while right hand swings tool handle
around toward your body (Figure 10-11). The
flute should start out facing top of workpiece,
and rotate upward as it moves deeper into the
bowl to maintain a clean even curve. As the tool
goes deeper into the bowl, progressively work
out toward the rim. It may be necessary to turn
the tool support into the piece as you get deeper
into the bowl.
(NOTE: Try to make one, very light continuous
movement from the rim to the bottom of the
bowl to ensure a clean, sweeping curve through
the piece. Should there be a few small ridges
left, a light cut with a large domed scraper can
even out the surface.)
7. Develop wall thickness at the rim and maintain
it as you work deeper into the bowl (Once the
piece is thin toward the bottom, you cannot
make it thinner at the rim). When the interior is
finished, move the tool support to exterior to re-
define bottom of bowl. (General rule of thumb:
the base should be approximately 1/3 the
overall diameter of the bowl).
8. Work the tight area around faceplate or chuck
with 1/4" bowl gouge.
9. Begin the separation with a parting tool, but do
not cut all the way through yet.
10.4.8 Sanding and finishing
1. Remove the tool support and adjust lathe speed
to approximately 500 RPM. High speed can
build friction while sanding and cause heat
check in some woods.
2. Begin with fine sandpaper (120 grit) and
progress through each grit, using only light
pressure. Coarser sandpaper tends to leave
deep scratches that are hard to eliminate. Use
power-sanding techniques to avoid concentric
sanding marks around your finished piece.
Avoid rounding over the rim and foot with
sandpaper; try to keep details crisp. Finish
sanding with 220 grit.
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Figure 10-11