TOOL MAKING AND STOCK CALCULATION
=91. Tongs.=—As tongs are among the most important tools and quite
difficult to make, they will be taken up in this chapter on tool making.
The weakest places in a pair of tongs are where the shoulders or
offsets are formed for the jaws and handles. These places should be
reënforced by fillets as large as the usefulness and appearance of the
tongs will permit; they should never be made sharp and square, unless
their construction demands it.
All tongs for general blacksmithing can be forged properly with the
hand hammer and the use of such tools as the top fuller, the swages,
and the round-edged set hammer. Some assistance with a light sledge
will be necessary. The use of such tools as a square-edged set or the
file for forming shoulders or fillets is very objectionable, especially
in the hands of unskilled workmen. If the two parts do not seem to
fit as they should, due to the fillets which are present, they will
generally adjust themselves when they are riveted together, heated, and
worked freely.
=92. Heavy Flat Tongs.=—Fig. 74. Fullering, forging, swaging, punching,
and riveting. Material: 15 inches of 7/8-inch square mild steel.
Mark the center of the 15-inch length with a hardy or cold chisel.
Form two depressions 3/8 inch deep, with a top fuller, one 2 inches
from the end at _a_, the other 3 inches from the same end but on the
opposite side. Form a third depression to the same depth, but at an
angle of 45 degrees, starting from the bottom of the first one, and on
the side indicated by the broken line, as at _b_. Draw the 2-inch end
to 1 × 1/2 inch from _a_, tapering to 1 × 3/8 inch at the end. This
portion forms one jaw, as shown at _c_. Now flatten out about 2 inches
of the metal from the beveled depression _b_ toward the center mark,
to 9/16 inch thick, allowing the metal to spread as wide as possible.
This should then be forged and formed into shape for the joint _d_, and
the fuller again placed in the second depression to make the dimension
there 5/8 inch, as shown at _d_.
[Illustration: FIG. 74.—STEPS IN MAKING HEAVY FLAT TONGS.]
Forge the other end in the same manner, exerting due care to have all
dimensions correspond; cut the stock in two at the center. Draw out
the heavy ends for the handles with the power hammer or with some
assistance from a sledge. They should be roughly forged at first with
an allowance for finishing as follows: Beginning at the joint, use the
top and bottom swages on the outer edges through the greatest width,
and swage to 5/8 × 1/2 inch. This swaging should be continued toward
the end to form the handle. By using the flatter during the swaging,
the sides may be kept straight, smooth, and slightly tapering to a
round section. Make the end 3/8 inch in diameter for a length of 3
inches. Sketch _F_ shows one side of a pair of tongs drawn and swaged.
Place the parts together to see if they fit properly; if they do not,
make the necessary alterations. Use a top fuller to form a groove _e_
about 1/8 inch deep, lengthwise on the inside of the jaws, and smooth
the sides and edges with a flatter. Then punch a 3/8-inch hole in the
center of the joint, as shown in sketch _F_. This should be done on
both parts.
Heat thoroughly the end of a 3/8-inch rivet, 1-3/4 inches long, and
with it rivet the two portions tightly together. Heat the tongs, make
them work freely, and adjust them to hold 3/8-inch flat iron, with the
entire length of the jaws in contact and with the ends of the handles
1 inch apart. The jaws and handles should be adjusted so that a line
extended lengthwise across the center of the rivet would pass midway
between them.
=93. Light Chain Tongs.=—Fig. 75. Forging, swaging, punching,
fullering, and riveting. Material: 13 inches of 3/4-inch square mild
steel.
[Illustration: FIG. 75.—STEPS IN MAKING LIGHT CHAIN TONGS.]
Mark the center of this length with a hardy or cold chisel. Form a
shoulder 1-1/4 inches from the end, and draw this end to 7/8 × 1/2 inch
at the bottom of the shoulder, tapering to 3/4 × 3/8 inch at the end,
as at _a_. Form a second shoulder at an angle of 45 degrees, starting
from the bottom of the first one, by holding the work on the anvil, as
shown at _b_. The blows should be directed a little toward the center
mark, to flatten and spread the metal for forming the joint of the
tongs. Form a third shoulder at _c_, 1 inch from and on the opposite
side to the first and toward the center mark, the thickness here being
1/2 inch. Note that these shoulders should be made with overhanging
blows and not by using the fuller. The metal between the shoulders
_c_ and _a_ should now be forged into shape for the joint. Forge the
other end in a similar manner, being careful to have all dimensions
correspond; then cut the stock in two at the center.
Draw out the heavy ends for the handles with a power hammer or with
some assistance from a sledge. Roughly forge them from 1/2 × 7/16 at
_c_, down to 5/16 inch round, 3 inches from the end. Finish the edges
by using the top and bottom swages. By using the flatter on the sides
during the swaging, the handle may be kept straight, smooth, and
slightly tapered to where it terminates into round. Sketch _F_ in Fig.
74 shows the handle drawn out and swaged.
[Illustration: FIG. 76.—THE COMPLETED LIGHT TONGS.]
Place the two parts together to see if they fit properly; if they do
not, make the necessary alterations. Taking each piece separately,
perform the following operations: Fuller a groove 1/8 inch deep,
lengthwise on the inside of the jaw, and another crosswise about 1/4
inch from the end as shown at _A_, Fig. 76. Then punch a 5/16-inch hole
in the center of the joint. A 5/16-inch rivet 1-1/2 inches long should
be obtained, its end should be thoroughly heated, and the two parts
riveted tightly together. Heat the tongs and make them work freely;
adjust them to hold 3/16-inch flat iron with the full length of the
jaws in contact, also to hold 3/8-inch round material in the cross
groove when the handles are 1 inch apart. They should be adjusted,
so that if a line were extended lengthwise through the center of
the rivet, it would pass midway between the jaws and handles. When
complete these tongs will appear as in Fig. 76.
=94. Lathe Tools.=—A complete description of lathe tools would require
too much space in this book, therefore only six common ones will be
explained; by applying the knowledge received from making these, the
operator should be able to forge many others. These with the other
tool steel exercises should supply sufficient practice in forging,
hardening, and tempering tool steel.
If these tools are to be put into practical use, a good quality of
tool steel should be provided, cut about 8 inches long for each one,
and great care should be taken in the heating, forging, and tempering.
If, however, they are to be made for practice alone, then much shorter
pieces may be conveniently used, also an inferior grade of steel;
mild or soft steel would be sufficiently good to provide the needed
practice in heating, forging, and tempering. Even though the material
is inferior, the operations should receive the most careful attention.
The material may be 1 × 1/2-inch, 7/8 × 3/8-inch, or any suitable stock
size.
[Illustration: FIG. 77.—BRASS TOOL.]
=95. Brass Tool.=—Fig. 77. Forging, hardening, and tempering. Material:
6 to 8 inches of 1/2 × 1-inch tool steel.
Starting about 3/4 inch from one end, draw to a uniform taper on both
sides and on one edge only, so that the metal is 1/4 inch thick and 1/2
inch wide at the end. The lower or beveled edge also should be drawn
thinner than the upper to provide the necessary clearance amounting to
about 5 degrees on each side, as shown in the sectional view. The end
should be cut off at an angle of 70 degrees and ground semicircular in
form with the necessary clearance.
Heat about 2 inches of this end and harden in the manner described for
the cold chisel, but in this case the color for tempering is a very
pale yellow.
=96. Cutting-off or Parting Tool.=—Fig. 78. Fullering, forging,
hardening, and tempering. Material: 7 inches of 1/2 × 1-inch tool steel.
[Illustration: FIG. 78.—CUTTING-OFF OR PARTING TOOL.]
With a top fuller form a depression across one side 5/8 inch from the
end, fullering the metal to 3/16 inch thick. Draw this end down to 1 ×
3/16 inch. The thickness of the metal where it was fullered should also
be decreased to 1/8 inch, gradually increasing to 3/16 inch at the end,
taking extreme care to have sufficient clearance from front to back and
from top to bottom. The cutting edge is generally allowed to project
about 1/8 inch above the stock; the end is trimmed off at an angle of
75 to 80 degrees and ground, as shown in Fig. 78, after which it is
hardened and tempered to a pale yellow.
=97. Heavy Boring Tool.=—Fig. 79. Drawing, bending, hardening, and
tempering. Material: 7 inches of 1/2 × 1-inch tool steel.
[Illustration: FIG. 79.—HEAVY BORING TOOL.]
Draw about 2-1/2 inches tapering to 1/2 inch square at the end; the
taper on the top edge should be only 1/8 inch, while that on the bottom
should be 3/8 inch, as shown at _a_. With the metal resting flat on the
anvil and the top edge to the left, bend down 3/4 inch of the end to an
angle of about 80 degrees, then forge down the corners from the point
back to the heel, to a slight octagonal form, as shown in Fig. 79.
Grind the projecting end of the angle semicircular with a clearance of
15 degrees, then harden and temper to a pale yellow.
=98. Light Boring or Threading Tool.=—Fullering, drawing, hardening,
and tempering. Material: 5 inches of 1/2 × 1-inch tool steel.
Using a top fuller, form a depression 7/16 inch deep on one edge and
2 inches from the end. Draw this metal slightly tapering to 7/16 inch
square at the end, keeping it straight on the top. With the metal
resting flat on the anvil and the straight edge to the left, bend down
3/4 inch of the end to an angle of 80 degrees, then forge the corners
between the angle and where the depression was formed to a slight
octagonal form.
For a boring tool, grind the projecting end of the angle semicircular
in form, with sufficient clearance for boring a hole of the desired
size; for a threading tool grind it to the proper angle of the thread
with sufficient clearance, then harden and temper it to a pale yellow.
=99. Diamond Point Tool.=—Fig. 80. Forging, hardening, and tempering.
Material: 7 inches of 1/2 × 1-inch tool steel.
[Illustration: FIG. 80.—FIRST STEPS IN MAKING A DIAMOND POINT TOOL.]
Using a top fuller, form a depression 3/8 inch deep on one edge 3/4
inch from the end, as at _a_. Then holding the depression over a round
edge of the anvil and delivering blows on the end, as indicated at
_b_, forge the 3/4-inch end into a square form, at an angle of 70
degrees to the lower edge of the stock, as shown at _c_. By resting the
inner corners of this end on the face of the anvil and delivering blows
on the opposite outside corners, as shown in Fig. 81, its form should
be changed to 7/16 inch square, projecting diagonally from the stock,
as shown at _a_, Fig. 82.
[Illustration: FIG. 81.—CHANGING THE FORM OF _c_, FIG. 80, TO THAT OF
_a_, FIG. 82.]
[Illustration: FIG. 82.—DIAMOND POINT TOOL, FINISHED.]
By using a sharp, hot cutter and cutting entirely from the right inside
surface (_a_, Fig. 82), and by holding the point over the edge of the
anvil, so that the operation will have a shearing effect, the excess
metal which extends more than 3/8 inch above the upper line of the
stock may be removed. For a right-hand tool the point should be set
1/8 inch to the left, as shown at _b_, the two outside surfaces being
ground smooth and forming an acute angle; the inside portion of the
end on the side indicated by _a_ should be ground somewhat shorter,
producing a diamond-shaped appearance. Harden and temper to a very pale
yellow.
Reverse the operations of cutting, setting, and grinding for a
left-hand tool.
=100. Right Side Tool.=—Fig. 83. Forging, offsetting, hardening, and
tempering. Material: 7 inches of 1/2 × 1-inch tool steel.
[Illustration: FIG. 83.—FIRST STEPS IN MAKING THE SIDE TOOL.]
[Illustration: FIG. 84.—SIDE TOOL.]
Heat and cut off about 5/8 inch of one corner, as at _a_, Fig. 83, and
form a depression with the top fuller 1-1/2 inches from the end on
the side indicated at _b_, 1/4 inch deep at the upper edge, leaving
the metal full thickness at the lower edge. Then the metal should be
roughly spread out from the upper edge of the stock by holding the
fuller lengthwise, as shown at _C_, leaving the lower edge the full
thickness, and smoothed with a flatter, drawing the upper edge to
1/8 inch in thickness. The above operations could be done with a hand
hammer, but not without considerable hard work.
[Illustration: FIG. 85.—OFFSETTING THE SIDE TOOL FOR CLEARANCE.]
Trim this end to the form shown in Fig. 84, by using a sharp, hot
cutter and cutting entirely from the side indicated by _d_. When this
has been done correctly remove all metal extending more than 1/4 inch
above the upper edge of the stock. When this has been forged to the
correct shape, heat and place the tool so that the fullered shoulder
is just beyond the edge of the anvil, then form the offset with a
round-edged set hammer, as shown in Fig. 85. Grind the upper edge
parallel with the stock but at a slight angle, to produce a cutting
edge, and grind the face side straight and smooth. In cooling this tool
for hardening it should be placed in the water, as shown in Fig. 86,
to insure hardening the whole cutting edge. Leave sufficient heat in
the heel or bottom of the tool to draw the temper uniformly to a pale
yellow.
[Illustration: FIG. 86.—HARDENING THE SIDE TOOL.]
=101. Forging Tools.=—The following forging tools are somewhat
smaller than those used in general smith work, but they are perfectly
serviceable and sufficiently heavy for manual training or considerable
ordinary work. The material for their construction should be tool steel
of 0.80 to 0.90 per cent carbon, 1-1/4 inches square, unless otherwise
specified. The holes or eyes should be punched straight, and the
precautions formerly given under the head of punches should be observed.
A tapered drift pin of an oval section 7/8 × 5/8 inch at the largest
end, also a smaller oval-shaped handle punch, should first be provided.
=102. Cold Chisel.=—Fig. 87. Forging, hardening, and tempering tool
steel. Material: 6-1/2 inches of 3/4-inch octagonal tool steel.
[Illustration: FIG. 87.—COLD CHISEL.]
First draw 1/2 inch of one end to a smooth, round taper about 3/8 inch
in diameter at the extreme end, then grind off the rough projecting
edges until it is 1/2 inch in diameter. This end should not be cooled
quickly, because it might harden somewhat, which would cause it to
break easily. Starting 2 inches from the opposite end, draw the tool
tapering to 1/8 inch thick and 1 inch wide, using the flatter on these
tapered sides and edges. They should be made straight and smooth, with
the edges perfectly parallel. Two views with dimensions are shown in
Fig. 87.
Grind the cutting edge of the chisel to the desired angle, then harden
and temper it as follows: Heat about 2 inches of the cutting end to a
dull cherry red and plunge about 1 inch of this perpendicularly into
water; withdraw it about 1/2 inch, and keep it in motion between the
first and second cooling places until the end is perfectly cold. Remove
the tool and quickly polish one side with emery cloth or sandstone,
watching the varying colors as they make their appearance and move
toward the edge; when the dark purple or blue color entirely covers
the point, thrust it into the water again and leave it there until
thoroughly cooled. Regrind cautiously, protecting the temper, and test
its cutting qualities on a piece of cast iron or soft steel.
=103. Hot Cutter.=—Figs. 88 and 89. Punching, fullering, forging,
hardening, and tempering. Material: 4 inches of 1-1/4-inch square tool
steel.
[Illustration: FIG. 88.—STEPS IN MAKING THE HOT CUTTER.]
[Illustration: FIG. 89.—HOT CUTTER.]
Punch and drift an eyehole 1-3/4 inches from the end, making all sides
straight and smooth, as shown at _a_, Fig. 88. With a pair of 3/4-inch
fullers, form two depressions on opposite sides 1/4 inch from the eye,
as at _b_, fullering the metal to 5/8 inch thick. From this place draw
the end tapering to 1-1/2 × 1/8 inch, and trim it off at a right angle
to the stock, as at _c_. Using a hot cutter and working equally from
all sides, cut the tool from the bar 1-1/4 inches from the edge of the
eye. Draw the head end tapering to about 7/8 inch from the eye, draw
the corners to form a slightly octagonal section. Remove all projecting
metal so as to produce a convex head. (See Fig. 89.) This will be
referred to later as forming the head. Grind both sides of the cutting
end equally to form an angle of 60 degrees, with the cutting edge
parallel to the eye. Harden, and temper to a dark purple or blue.
=104. Cold Cutter.=—Figs. 90 and 91. Punching, forging, hardening, and
tempering. Material: 4 inches of 1-1/4-inch square tool steel.
[Illustration: FIG. 90.—STEPS IN MAKING THE COLD CUTTER.]
[Illustration: FIG. 91.—COLD CUTTER.]
Punch and drift an eye 2 inches from the end _a_, Fig. 90. Draw this
end tapering on the sides parallel with the eye, forming convex
surfaces and terminating in 1 × 3/16 inch. (See sketches _b_ and _c_.)
Cut the tool off at _c_, 1-1/4 inches from the eye, and form the head.
Grind the cutting end equally from both sides to form an angle of
60 degrees, and a convex cutting edge similar to that shown at _d_.
Harden, and temper to a dark purple or light blue. The finished tool is
shown in Fig. 91.
[Illustration: FIG. 92.—SQUARE-EDGED SET HAMMER.]
=105. Square-edged Set.=—Fig. 92. Punching and forging. Material: 3-1/2
inches of 1-inch square tool steel. Heavier or lighter stock may be
used if desired.
Punch and drift an eye 1-1/4 inches from the end, then, using a pair
of 3/8-inch fullers, form depressions about 1/8 inch deep across the
corners, as at _a_, Fig. 92. Cut the tool off 1-1/2 inches from the
eye, and form the head to 3/4 inch at the end. Heat and anneal in warm
ashes; when it is cold, grind the face smooth, straight, and at right
angles to the stock.
=106. Hardy.=—Fig. 93. Fullering, forging, hardening, and tempering.
Material: 3 inches of 2 × 7/8-inch tool steel.
Using steel 2 inches wide with a thickness equal to the dimension of
the hardy hole, fuller and draw a slightly tapered shank 1-3/4 or 2
inches long, to fit loosely into the anvil. The broken lines at _a_,
Fig. 93, indicate the drawn shank. Cut off the stock 1-1/2 inches from
the shoulders at _b_. Heat and drive the drawn end into the hardy hole
so as to square up the shoulders and fit them to the anvil. Then draw
the heavy end tapering gradually from the sides, terminating 1/8 inch
thick and 2 inches wide. Grind this tool similar to the hot cutter;
harden, and temper to a purple or blue.
[Illustration: FIG. 93.—HARDY.]
[Illustration: FIG. 94.—FLATTER OR ROUND-EDGED SET HAMMER.]
=107. Flatter.=—Fig. 94. Upsetting, forging, and punching. Material:
4-3/4 inches of 1-1/2-inch square tool steel.
In forming the face of a flatter, the metal should be upset. This
may be accomplished by ramming, but when so done, excess metal is
formed just above the wide portion, causing considerable fullering
and forging. If a piece of steel 4-3/4 inches long and 1-1/2 inches
square is cut off, and one end is drawn slightly tapering, it may,
when heated, be placed in a square hole of the right size in the swage
block, with the drawn end supported on something solid, leaving 1-1/2
inches projecting. The hot steel can then be hammered down with a
couple of sledges, until the face is formed to 3/8 inch thick or about
2 inches square, as at _a_, Fig. 94.
Punch and drift an eyehole 1-1/4 inches from the face, then draw and
form the head. Anneal in warm ashes. When it is cold, the face should
be ground perfectly straight, smooth, and at a right angle to the body,
with the surrounding edges slightly round, as shown, or they may be
left sharp and square if desired.
A round-edged set hammer may be made in this manner, but as the face
should not be so large, less metal is required.
=108. Small Crowbar.=—Fig. 95. Drawing, swaging, welding, and tempering
steel. Material: 16 inches of 3/4-inch square mild steel, also a small
piece of tool steel.
[Illustration: FIG. 95.—STEEL-FACED CROWBAR.]
Draw 11 inches to the following dimensions: the first 4 inches to
3/4-inch octagon, then beginning with 3/4-inch round gradually reduce
to 1/2-inch round at the end. This should be smoothly forged and swaged.
Form a depression 1/4 inch deep on one side of the square portion 2
inches from the end; from this, draw the metal to 1/2 × 3/4 inch; by
using a hot cutter where the depression was made, split and raise up a
scarf fully 3/4 inch long, as shown in the sketch. Prepare a piece of
tool steel 2-1/2 × 3/4 × 1/2 inches; on one end of this draw a long,
thin scarf and roughen it with a hot cutter, so it can be held in
place securely. (See Fig. 95.)
Heat the bar cautiously where the scarf was raised, to avoid burning
it; slightly cool the tool steel and put it into place. By holding
the piece of steel against a hardy, swage, or fuller, the scarf can
be hammered down tightly over the tool steel, which should hold it
securely for heating. Place the pieces in the fire and heat them to
a red; remove and thoroughly cover them with borax; replace them and
raise the heat to a bright yellow or welding heat.
While the first light blows for the welding are being delivered, the
end should be held against something to prevent the steel from being
displaced; when positive that welding is proceeding, make the blows
heavier and complete the operation.
When the pieces are securely joined, cut off the corner opposite to
the steel face, and draw the bar tapering from this side, to a sharp,
flat edge 1 inch wide. Bend this through its smallest dimensions to an
inside radius of about 3-1/2 or 4 inches and with the edge extending
1/2 inch to one side of the bar, as in Fig. 95. File or grind the
outside surface and edge of this; then harden, and temper to a blue.
=109. Eye or Ring Bolts.=—An assortment of eyes is shown in Figs. 96,
97, and 98. All eyes should possess two essentials: the necessary
strength and a good appearance; therefore the method of making should
be chosen to fulfill those requirements. Generally the eyes that have
the most strength require the greatest amount of labor.
_A_, Fig. 96, is an open eye which is very easily made, because bending
is the only operation required. The method of making this form of eye
has already been explained in section 69.
[Illustration: FIG. 96.—EYE OR RING BOLTS.
_A_, an open eye; _B_, a welded eye.]
_B_ is a welded eye. It is made by forming first a flat, pointed scarf
on the end of the bar and bending it through its smallest diameter
where the drawing was begun. This bend should be no less than 70
degrees on the outer side. Determine the length of the material needed
for forming a ring of the required diameter, then subtract the diameter
of the material from the determined length. Using this result, place a
center-punch mark _f_ that distance from _e_, and bend the piece at _f_
in the same direction as _e_.
Form the metal between the bends into a circle, and place the scarf in
position for welding, as at _B_. During the heating for welding, if the
circle heats more rapidly than desired, it should be cooled off and
the heating then continued. The welding should be done as quickly as
possible and swaged if required.
The eye bolt, shown in Fig. 97, is similar to a solid forged eye. It
is formed and welded with a specially forged scarf called a butterfly
scarf.
Determine the amount of material needed to form a ring of the required
diameter, and add to that a sufficient allowance for upsetting and
welding, which would be approximately equal to the diameter of the
material used. An invariable rule for that allowance cannot be given,
because the results of the upsetting are seldom the same.
Place a center-punch mark the estimated distance from one end of the
bar; then upset the end 1/8 inch larger than its original diameter,
next upset it at the mark to a similar dimension, and bend it there to
an angle of no less than 70 degrees. Now with the bend lying flat on
the face of the anvil, draw out a thin, narrow scarf with a small ball
peen hammer, not any wider than the thickness of the metal. The scarf
may be drawn also by holding the outer portion of the bend on a sharp
corner of the anvil and by drawing with overhanging blows. This scarf
is shown in the upper view of Fig. 97 as it should appear.
[Illustration: FIG. 97.—EYE BOLT MADE WITH A BUTTERFLY SCARF.]
The butterfly scarf should now be formed on the opposite side from
the one just finished, by holding each side of the end at an angle of
about 45 degrees on the edge of the anvil; this scarf may be drawn
with overhanging blows. The extreme end should also be drawn thin in a
similar manner, while it is held at a right angle with the edge of the
anvil. All outer edges of this scarf should be thin and sharp.
Bend the metal into a circle and place the scarfs in position, as shown
at _C_, having all edges overlapping slightly and hammered down into
close contact. Heat the work for welding, observing the precaution
given in the explanation of the former eye. In welding, deliver the
first few blows uprightly on each side, then weld the edges of the
scarfs with the ball of the hammer. A few careful experiments with
these scarfs will show what is required, and with practice no more
labor will be needed than is required for the previous eye. The
finished product will be more substantial and presentable.
[Illustration: FIG 98.—_D_, A SHIP-SMITH EYE; _E_, A SOLID FORGED EYE.]
_D_, Fig. 98, is generally called a ship-smith eye, because it is
commonly used in ship work where strength is essential. Special swages,
convex lengthwise, are usually provided for shaping the concave curves
where they are formed and welded. The eye should be circular between
the places indicated by _f_ in sketch _D_, and the lines from _f_
to where it is welded should be as nearly straight as possible, to
increase the strength.
In estimating the material, take two thirds of the length for a ring
of the required diameter, and add to that the proper allowance for the
stock which forms the portion from _f_ to the weld, and also an amount
sufficient for the scarf. This scarf is drawn similar to the one for
the welded eye in Fig. 96, but it should be made convex through its
smallest dimension with a top fuller, whose diameter is equal to that
of the metal. This is done while the metal is held in a bottom swage of
corresponding size. When the scarf is finished, bend the eye into shape
and bring the scarf close up to the stem of the eye.
Heat and weld with swages; if convex swages are not obtainable, others
may be used by taking care to prevent marring the curves. This eye may
also be welded with a large fuller while it is held over the horn of
the anvil. If the curves are severely marred, the strength of the eye
is lessened.
A solid forged eye is shown at _E_. When eyes like this are drop-forged
in special dies, as they generally are, they do not require much skill,
but when made entirely by hand they require considerable experience.
In forging an eye of this kind, the volume of material needed must
first be determined, making some extra allowance for the usual waste.
A convenient size of material should then be selected (round is
preferable) and the amount required for the eye marked off. The round
stem should be drawn down to size and the part for the eye forged to
a spherical shape, then flattened, punched, and enlarged to correct
dimensions.
=110. Calipers.=—The calipers shown in Fig. 99 may be easily made from
the dimensions given; 3/4 × 1/8-inch stock should be used for the main
piece, and 1/2 × 1/8-inch stock for the legs.
=111. Stock Calculation for Bending.=—In the expansion and contraction
of metals during the operation of bending, there is a fixed line,
where the metal is left undisturbed; in other words, where it is
not increased or decreased in length. So all measurements taken to
determine the length of material required for producing any bent shapes
should be taken from that fixed or undisturbed location, in order to
attain accurate results.
All materials which have a symmetrical cross section, such as round,
square, octagonal, oval, or oblong, have the above line at their true
centers, no matter which way they are bent. While the metal remains
undisturbed at the center of any of the above sections, the rest of
it undergoes a change; the inner portion, in the direction of bending,
will contract and become thicker, and the outer portion will expand and
become thinner.
[Illustration: FIG. 99.—STEPS IN MAKING CALIPERS.]
Other conditions arise, however, to modify these rules. If the heat is
unevenly distributed, or if the stock is not of a uniform thickness,
the results will not be exactly as estimated. When a heavy ring is
formed of oblong material and bent through its larger diameter, as
shown in sketch _A_, Fig. 100, and the product is to be finished to
a uniform thickness, the expansion of the outer portion will make it
necessary to use somewhat thicker material, to provide for the decrease
of metal which will take place. The inner half, then too thick, could
be reduced to the required size, but this operation always alters
natural conditions of bending, and changes the general results. These
conditions are not very noticeable and do not require special attention
when small-sized materials are operated upon, but they must be observed
when large oblong or square stock is formed into a ring requiring exact
dimensions.
[Illustration: FIG. 100.—CALCULATIONS OF LENGTHS FOR RINGS.]
In all cases of this kind, the required length must be established from
the undisturbed center and the ends cut at an angle of 85 degrees. If
the material is to be welded, it should be scarfed on opposite sides
and lapped when bent.
When hoops or bands of flat or oblong material are bent, scarfed, and
welded through the small diameter, then both scarfs should be formed on
the same side while straight, and bent as shown at _B_, Fig. 100; the
scarfs then will fit more readily than if they were formed on opposite
sides. Sometimes, in instances of this kind, only one end is scarfed,
and the piece is bent in a similar manner, with the unscarfed end on
the outside and just lapping enough to cover the heel of the inner
scarf.
Another form of ring requiring a calculation of the area as well as
of the length is one of a wedge-shaped section, as shown at _C_, Fig.
100. Here the area of the required section is found and the material
supplied with the proper thickness and area. The length also must be
computed, then cut, scarfed, and welded, as previously explained; after
this the ring may be drawn to the form desired.
The circumference of a circle may be found by multiplying its diameter
by 3.1416 (π). (See tables, pages 205-206.) For rings or bands the
length of the center line, _c_, Fig. 100, should be found. Example: If
_a_ equals 5 inches and _b_ equals 2 inches, _c_ will equal 7 inches,
and the length of stock for the ring will be 7 × 3.1416 = 21.991
inches,—practically 22 inches. 3-1/7 may be used for the value of π
instead of 3.1416.
QUESTIONS FOR REVIEW
Describe the proper construction of a pair of tongs. What sort of
steel should be used in making lathe tools? What operations are
employed in making them? What is the color of the temper? If they
were tempered to a blue, would they be tempered harder or softer?
Are forging and hardening heats the same? State the difference in
grinding a boring and a threading tool. Explain the difference in
making a right- and a left-hand diamond point tool. How should a side
tool be hardened? Why shouldn’t the head of a cold chisel be cooled
off quickly when it is finished? Explain the difference between
tempering a cold chisel and tempering a lathe tool. Describe the
shapes of the hot and the cold cutter. How should they be tempered?
How are the square-edged set and the flatter treated in place of
tempering. Explain how it is done. Describe different methods of
making eye or ring bolts. How should measurements be made on stock
to be bent? State what has been said about scarfing flat or oblong
material for rings.