Craftsman 351.21 7150 Manual De Instrucciones página 10

canbeabove t heworkpiece centerline, and somewhat out
from thework surface. With small diameter work (Figure
25G), therestshould b ecloser t othework surface. As
work grows s maller, therest s hould b erepositioned.
How to Position Tool Rest for Circumference Scraping
In scraping operations, the tool rest position is not as critical
as it is for cutting operations.
• The chisel generally is held horizontally, though it can be
held at an angle to reach into tight places. Considering that
the wire edge of the chisel does the scraping, Figures 26B
and 26C show the results of too low or toe high a position
for the rest.
Figure 26A shows the chisel action with the rest correctly
positioned.
Fig. 26A Fig. 26B Fig. 26C
"_" Digging [
In
C
Figure 26
How to Position Chisel and Rest for Diameter Scraping
When scraping on the diameter, that portion of surface to the
right of center is moving upward (Figure 27A). If a chisel is
placed in this area, it will simply be carried up off the rest and
out of your hands.
• All diameter approach operations must be done at the left
of center.
Three different chisel contact points are shown in Figure 27B.
It will be noted that when a chisel is above the workpiece cen-
ter (or below it) the work surface sweeps past the chisel edge
at an angle and tends to carry the chisel in one direction or
the other along the rest.
Only when the chisel contacts the work on the centedine,
does the work surface pass squarely under the chisel
edge. This, then, is the position in which it is easiest to
hold the chisel steady. To obtain this position, place the
rest approximately YF' (thickness of chisel) below center.
Fig. 27A
Fig. 27B
4
LI___
Figure 27
USING THE GOUGE
Three gouges, the I/4, _t_and 3/4" sizes, are adequate for gener-
al homeshop turning. Other sizes from Y8to 2" can be pur-
chased to provide more flexibility.
The chief use of the gouge is for rough circumference cutting
of raw stock down to a cylinder of working size. It is best to
use this tool for rapid cutting away of large areas of the work-
piece. When the tool is used this way, it does not produce a
smooth surface. With practice, the gouge can be used for cut-
ting coves and the shaping of long cuts.
Figure 28
Cutting Edge
Advanced
Wrong
Right
When used for cutting, the gouge is always held with the con-
vex side down. it should be rolled approximately 30 ° to 45 ° in
the direction in which it is being advanced along the rest and
the cutting edge should be slightly ahead of the handle.
USING THE SKEW
• Two skews, the _/2 and 1" sizes, are all that are needed for
general use. Other sizes are available.
This tool is nearly always used to make finished cuts, to cut vees
and beads, and to square shoulders. Properly used, it produces
the best finish that can be obtained with a chisel. It is not recom-
mended for scraping because the edge tends to dull more quickly.
• For finish cutting, the skew is held with the cutting edge
considerably in advance of the handle, bevel side down.
Keep the base of the bevel against the work. It is good
practice is to place the skew well over the work, pull it back
until the edge begins to cut, then swing the handle into
position to advance the cut.
Both the toe and the heel of the skew can be used for taking light
cuts, but do not penetrate the wood too deeply without cutting
clearances. There is danger of burning the tip of the tool.
Pul! Ba_c_k S_wing
OF CUT
Tool
Using Toe Using Heel I/v
Figure 29
USING THE PARTING TOOL
The parting tool has just one primary purpose: to cut into the
workpiece as deeply as desired, or all the way through to make a
cut-off. It is, therefore, a very narrow tool _/8" wide) and shaped to
cut its own clearance so that the edge will not be burned. When
used for scraping, however, the parting tool should be backed off
regularly to prevent overheating.
Unlike the gouge and skew, the parting tool is seldom held with
the bevel against the work. Since the amount of stock removal is
small, a support for the bevel is not necessary.
The tool is simply fed into the work at an angle (for cutting), or
pointed at the workpiece center (for scraping). It can be held eas-
ily in one hand.
Cutting Scraping
4--..- 4"-'-
F,gure o d/
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