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ROUGH-CUTTING
TO SIZE
The roughing-off cut can be made to accurately size the
cylinder to a given diameter.
Another method is to make a number of sizing cuts at inter-
vals along the work, then use the gouge to reduce the whole
cylinder down to the diameter indicated by these cuts.
MAKING SIZING CUTS
Sizing cuts are useful to establish approximate finished size
diameters at various points along a workpiece. The work can
then be turned down to the diameters indicated and be ready
for finishing.
•
Diameters for sizing cuts should be planned to be about 1/8"
greater than the desired finish diameters. A sizing cut is
made with the parting tool.
•
Hold the tool in one hand, and use the other hand to hold
an outside caliper preset to the desired sizing-cut diameter.
•
As the cut nears completion,
lower the chisel point more
and more into a scraping position.
•
When the calipers slip over the workpiece at the bottom
of the groove, then the cut is finished.
Figure 41
SMOOTHING
A CYLINDER
The final 1/8"can be removed in two ways. Either use the 1"
skew, working from the center toward both ends and taking
lighter and lighter cuts until finished, or use a block plane
as illustrated in Figure 29.
CUTTING A SHOULDER
A shoulder can be the side of a square portion left in the
workpiece, the side of a turned section, or the end of the
workpiece. Most shoulders are perpendicular
to the work
axis, but a shoulder can be at any angle.
•
First, mark position of the shoulder with a pencil held to
the revolving workpiece.
•
Second, make a sizing cut with the parting tool, placing
this cut about 1/16" o utside the shoulder position and cutting
to within about 1/8"of the depth desired for the area outside
of the shoulder.
•
If shoulder is shallow, the toe of the skew can be used
to make the sizing cut. Do not go in deeper than 1/8" with
the skew unless wider and wider vees are cut to provide
clearance for this tool.
Figure 42
"_
•
Use the gouge to remove any waste stock outside of shoul-
der. Smooth this section, up to within 1/8"of shoulder, in the
usual manner. Finishing of the shoulder, unless it is more
than 1" high, is best done with the 1/8" skew.
13
• The toe of the skew is used to remove the shavings
from the side of the shoulder - down to finished size.
•
Hold skew so the bottom edge of bevel next to the shoul-
der will be very nearly parallel to side of shoulder - but
with cutting edge turned away at the top so that only
the extreme toe will do the cutting. If cutting edge is
flat against shoulder, the chisel will run.
•
Start with handle low, and raise handle to advance toe
into the work.
•
Cut down to finished diameter of outside area. Then, clean
out the corner by advancing heel of the skew into it along
the surface of the outside area.
• Tilt the cutting edge, with handle raised up so that only
the extreme heel does this cutting.
•
If shoulder is at end of work, the process is called squaring
the end. In this case, reduce outer portion to a diameter
about 1/4"larger than tool center diameter. Then, later,
saw off the waste stock.
Wrong
Right
Figure 43
CUTTING VEES
Vee grooves can be cut with either the toe or heel of the skew.
•
When the toe is used, the cutting action is exactly the
same as when trimming a shoulder except that the skew
is tilted to cut at the required bevel. Light cuts should
be taken on first one side and then the other, gradually
enlarging the vee to the required depth and width.
•
When the heel is used, the skew is rotated down into the
work, using the rest as a pivot. Otherwise, cutting position
and sequence of cuts are the same. As when using the
toe, it is important that cutting be done only by extreme
end of cutting edge.
•
If deep vees are planned, it is quicker to start them by
making a sizing cut at the center of each vee.
•
Vees can also be scraped with the spear point chisel
or a three-sided file.
Figure 44
CUTTING BEADS
This operation requires considerable practice.
•
First, make a pencil line to locate the tops (highest points)
of two or more adjoining beads.
• Then, make a vee groove at the exact center between two
lines and down to the desired depth of the separation
between the beads. Be careful not to make the groove too
wide or you will remove portions of the desired beads. The
sides of the two adjoining beads are now cut with the heel
of the skew. Use a 1/8" skew, unless beads are very large.
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