Powermatic 3520B - Manual (Page 27)

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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 39.
Figure 39
6. Use the left hand to control cutting edge of
gouge, while right hand swings tool handle
around toward your body (Figure 38). 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.
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.
3. Remove sanding dust with tack rags or
compressed air and, with lathe turned off,
apply first coat of finish. Let stand for several
minutes, wipe off excess. Allow to dry before
sanding again with 320 or 400 grit
sandpaper.
4. Turn lathe back on and continue the
separation cut almost all the way through
the base. Stop at about 3" and use a small
fine tooth saw to separate the bowl from the
waste.
5. Apply second finish coat and allow to dry
before buffing.
Maintenance
Before doing maintenance on
the Lathe, disconnect it from the electrical
supply by pulling out the plug or switching
off the main switch. Failure to comply may
cause serious injury.
Maintenance on the 3520B Lathe should be
performed at periodic intervals to ensure that the
machine is in proper working order, that all
fasteners are tight, and all necessary
adjustments have been made. Inspection and
maintenance should be performed at least twice
a year, but more frequently if the Lathe receives
constant use.
Clean and oil the lathe bed(s) so that headstock,
tailstock and tool support base will slide easily.
Clean any rust spots that may develop on the
bed with a commercial rust remover.
Use compressed air to blow out the interior of
the headstock, in order to keep sawdust and
chips from accumulating on belts and sheaves.
Also blow off debris that accumulates on the
inverter. Do not disassemble inverter to
clean!
Frequently clean out the morse tapers on both
headstock and tailstock. Commercially available
taper cleaners may be acquired from tool stores.