_Round nose:_ The drawing gives the form and the dimensions.
[Illustration: Round nose]
_Stock:_ A piece of 7/16 × 7/8 × 7 in. tool steel.
This size best fits the tool post of the lathe. You see by the sketch
that one end is bevelled. This end is always made first. It is done
by heating and chamfering the edges down with a hand hammer. Place
the other end in the fire and draw it out to a sharp point in both
directions. Throw the bevel on one side by placing the tool on the
anvil and driving one side of the metal down to the other side. The
point is now cut off on a bevel for clearance.
The drawing shows a cross section view of the tool. Notice that it
is smaller on the bottom than on the cutting edge. This is done by
reducing one side more than the other. The cutting edge of the tool
should extend about 1/32 in. above the common level.
_Hardening and tempering:_ All lathe tools of this type are hardened
and tempered in the same way as you did the cold chisel. The temper
colour of this tool is a very light straw. When this colour reaches
the extreme point plunge the tool into water. The slight change of
temperature does not materially lessen the degree of hardness, but it
does toughen the tool so that it will do more work.
[Illustration: Diamond point]
_Diamond point:_ The form and dimensions are given.
_Stock:_ 7 × 7/16 × 7/8 ins.
[Illustration: Side tool]
Heat one end and bevel it off as you did when making the round nose
tool. Place the other end in the fire, 5/8 in. from the end, and
fuller down to one half the thickness of the bar. This fullering is
done on the bottom fuller, which is placed on the anvil. Re-heat this
end, place it again on the fuller in the depression made, and with the
hand hammer draw this end out and at the same time square it up into a
diamond point by turning the tool at an angle of 45° with the anvil.
Turn again, in exactly the opposite direction. Repeat this until the
point of the tool is drawn out as shown by the sketch. The clearance
should not be more than that shown. It is now cut off by placing the
face of the diamond on the outer edge of the anvil. Place the cold
chisel above this edge, strike the chisel with the sledge hammer and
cut it off. If this is carefully done it will cut the proper bevel for
the cutting edge. The drawing shows the slope of the cutting edge to be
parallel to the top of the tool. The tool is hardened and tempered the
same as the round nose tool.
_Side tool (right hand):_ The form and dimensions are given here.
_Stock:_ 7 × 7/8 × 7/16 in.
To make a tool of this kind bevel off the end of the stock, place the
other end in the fire, and heat about two inches to a red heat. Take it
out and place about one inch of this on the round edge of the anvil.
With the hand hammer reduce the thickness of this steel, driving on
the edge nearest you (see sketch marked A). The hammering reduces the
thickness of the edge, which will be the cutting edge when finished.
The part opposite to where you are working will be reduced very little.
A chisel is now used for cutting the cutting edge on the tool (see B).
Place the tool on a piece of soft iron, place the chisel along the line
and cut through to the soft iron below. This gives not only a clear cut
but prevents the chisel from driving in if it should strike the hard
anvil. The clearance is cut off along the other lines. (C) The cutting
edge is now offset. To do this use a set hammer. Push the part made
beyond the anvil 1/4 in. Place the set hammer in this shoulder, drive
down until the offset is driven down about 1/8 in. (D).
The method of tempering this tool is a little different from the way
you have tempered other tools, on account of the length of the cutting
edge, which should be hardened its full length. Place the end just
finished in the fire and heat to a red heat. Plunge the whole tool into
water. Take it out and polish the cutting edge with emery stone. Now
place in the fire a piece of any kind of iron; 1 in. square will do.
Heat it red hot, then place it upon the anvil, and lay the part of your
tool that has been hardened on the hot bar. It will draw enough heat
from the hot bar to produce the temper colours. This is one way to give
a piece of hardened steel the heat to temper it when the body of that
piece does not contain heat enough to do so.
[Illustration: Boring tool]
_Boring tool:_ Boring tools are made for the purpose of enlarging holes
in cylinders, or any hole which should be enlarged after it has been
drilled. The work to be done must determine the size and length of the
boring tool. This is not true of any other one of the lathe tools.
_Stock:_ 7 × 7/16 × 7/8 in.
Bevel one end. Place the other end in the fire and heat about 3 ins. of
it. Draw it out to a tapering octagonal shape, as shown in the sketch.
The end is pushed over the anvil about 1/2 in. Drive it down at right
angles. The clearance for the cutting edge is cut off with a hot chisel
and made ready for hardening and tempering.
[Illustration: Cutting-off tool]
_Cutting-off or parting tool:_ This tool is made for dividing bars of
metal into different lengths. The form and dimensions are here shown.
_Stock:_ 7 × 7/8 × 7/16 in. tool steel.
Bevel one end. Place the other end in the fire and heat about 1 in.
Place the fuller on the anvil. Put the top fuller on this, then put
the steel between the two fullers about 1/2 in. from the end. Using the
sledge hammer, drive down so that the centre thickness will measure 1/8
in. Draw the lump left on the end to 1/8 in. thickness, the same width
as the tool. The drawing shows that the clearance on this tool is one
half the thickness of the cutting edge, or 1/16 in. This clearance must
be put on as shown in the drawing, otherwise the tool will not clear
while doing the cutting. Finish up as shown in the sketch. Harden and
temper in the same way as you did the round nose tool. Cutting off
tools are made with the shoulder all on one side. (See sketch and see
article on tempering steel.)