Two plates or pieces to be riveted together have holes punched or
drilled in them in such a manner that one may be made to overlap the
other so that the holes in the one may be opposite the holes in the
other. The rivets, which are round bars of iron, or steel, or other
metal, are heated to redness and inserted in the holes; the head already
formed on the rivet, and called the tail, is then held up, and the point
is hammered or pressed so as to form another head. This process of
forming the second head on the rivet is known as riveting, and may be
done by hand-hammering or by a machine.
_Forms of Rivet Heads._--In fig. 1 are shown four different forms of
rivet heads: (_a_) is a _snap head_, (_b_) a _conical head_ (_c_) a
_pan head_, and (_d_) _a countersunk head_.
_Proportions of Rivet Heads._--The diameter of the snap head is about
1.7 times the diameter of the rivet, and its height about .6 of the
diameter of the rivet. The conical head has a diameter twice and a
height three quarters of the rivet diameter. The greatest diameter of
the pan head is about 1.6, and its height .7 of the rivet diameter. The
greatest diameter of the countersunk head may be one and a half, and its
depth a half of the diameter of the rivet.
[Illustration: FIG. 1.]
In fig. 1 at (_a_) and (_b_) are shown geometrical constructions devised
by the author for drawing the snap and conical head for any size of
rivet, the proportions being nearly the same as those given above.
_Geometrical Construction for Proportioning Snap Heads._--With centre A,
and radius equal to half diameter of rivet, describe a circle cutting
the centre line of the rivet at B and C. With centre B and radius BC
describe the arc CD. Make BE equal to AD. With centre E and radius ED
describe the arc DFH.
_Construction for Conical Head._--With centre K, and radius equal to
diameter of rivet, describe the semicircle LMN, cutting the side of the
rivet at M. With centre M and radius MN describe the arc NP to cut the
centre line of rivet at P. Join PL and PN.
When a number of rivets of the same diameter have to be shown on the
same drawing the above constructions need only be performed on one
rivet. After the point E has been discovered the distance AE may be
measured off on all the other rivets, and the arcs corresponding to
DFH drawn with radii equal to ED. In like manner the height KP of the
conical head may be marked off on all rivets of the same diameter with
conical heads.
_Caulking._--In order to make riveted joints steam- or water-tight the
edges of the plates and the edges of the heads of the rivets are burred
down by a blunt chisel or caulking tool as shown at Q and R.
[Illustration: FIG. 2.]
[Illustration: FIG. 3.]
EXERCISE 1: _Forms of Rivets._--Draw, full size, the rivets and
rivet heads shown in fig. 1. The diameter of the rivet in each
case to be 1-1/8 inches, and the thickness of the plates 7/8 inch.
EXERCISE 2: _Single Riveted Lap Joint._--Draw, full size, the
plan and sectional elevation of the _single riveted lap joint_
shown in fig. 2.
_Table showing the Proportions of Single Riveted Lap Joints for various
Thicknesses of Plates._ (_Plates and Rivets Wrought Iron._)
+--------------+-------------+----------+--------------+
| Thickness of | Diameter of | Pitch of | Width of lap |
| plates | rivets | rivets | |
+--------------+-------------+----------+--------------+
| 1/4 | 9/16 | 1-5/8 | 1-3/4 |
| 5/16 | 5/8 | 1-3/4 | 2 |
| 3/8 | 11/16 | 1-7/8 | 2-1/4 |
| 7/16 | 3/4 | 2 | 2-1/2 |
| 1/2 | 13/16 | 2-1/8 | 2-3/4 |
| 9/16 | 7/8 | 2-1/4 | 2-7/8 |
| 5/8 | 15/16 | 2-5/16 | 3 |
| 11/16 | 1 | 2-3/8 | 3-1/8 |
| 3/4 | 1-1/16 | 2-1/2 | 3-1/4 |
+------------------------------------------------------+
All the dimensions are in inches.
[Illustration: FIG. 4.]
EXERCISE 3.--Draw, half size, a plan and section of a single
riveted lap joint for plates 3/4" thick to the dimensions given in
the above table.
EXERCISE 4: _Double Riveted Lap Joint._--Draw, full size, the two
views of the _double riveted lap joint_ shown in fig. 3.
_Table showing the Proportions of Double Riveted Lap Joints for various
Thicknesses of Plates._ (_Plates and Rivets Wrought Iron._)
+-----------+-------------+----------+------------------+----------+
| Thickness | Diameter of | Pitch of | Distance between | Width of |
| of plates | rivets | rivets | rows of rivets | lap |
+-----------+-------------+----------+------------------+----------+
| 3/8 | 11/16 | 2-1/2 | 1-1/8 | 3-1/2 |
| 7/16 | 3/4 | 2-5/8 | 1-1/4 | 3-3/4 |
| 1/2 | 13/16 | 2-3/4 | 1-3/8 | 4 |
| 9/16 | 7/8 | 2-7/8 | 1-7/16 | 4-1/4 |
| 5/8 | 15/16 | 3 | 1-9/16 | 4-1/2 |
| 11/16 | 1 | 3-1/8 | 1-3/4 | 4-3/4 |
| 3/4 | 1-1/16 | 3-1/4 | 1-7/8 | 5 |
| 13/16 | 1-1/16 | 3-3/8 | 1-7/8 | 5 |
| 7/8 | 1-1/8 | 3-1/2 | 1-15/16 | 5-1/4 |
| 15/16 | 1-1/8 | 3-5/8 | 1-15/16 | 5-1/4 |
| 1 | 1-3/16 | 3-3/4 | 2 | 5-1/2 |
+-----------+-------------+----------+------------------+----------+
[Illustration: FIG. 5.]
EXERCISE 5.--Draw, half size, a plan and section of a double
riveted lap joint for plates 7/8 inch thick to the dimensions
given in the above table.
EXERCISE 6: _Single Riveted Butt Joints._--In fig. 4 are shown
_single riveted butt joints_. One of the sectional views shows a
butt joint with one _cover plate_ or _butt strap_; the other
sectional view shows the same joint with two cover plates; the
third view is a plan of both arrangements. Draw all these views
full size.
EXERCISE 7.--Fig. 5 shows a plan and sectional elevation of the
connection of three plates together, which are in the same plane,
by means of single riveted butt joints and single cover plates.
The butt straps where they overlap are forged so as to fit one
another as shown, and thus form a close joint. Draw these views to
the scale of 6 inches to a foot.
The plates are 1/2 inch thick and the butt straps 9/16 inch thick.
All other dimensions must be deduced from the table for single
riveted lap joints.
EXERCISE 8.--The connection of three plates by single riveted lap
joints is shown in fig. 6. To make the joint close one plate has a
portion of its edge thinned out, and the plate above it is set up
at this part so as to lie close to the former.
Draw the three views shown in fig. 6 to the same scale as the last
exercise.
The plates are 7/16 inch thick. All other dimensions to be
obtained from table for single riveted lap joints.
EXERCISE 9: _Corner of Wrought-iron Tank._--This exercise is to
illustrate the connection of plates which are at right angles to
one another by means of _angle irons_. Fig. 7 is a plan and
elevation of the corner of a wrought-iron tank. The sides of the
tank are riveted to a vertical angle iron, the cross section of
which is clearly shown in the plan. Another angle iron of the same
dimensions is used in the same way to connect the sides with the
bottom. The sides do not come quite up to the corner of the
vertical angle iron, excepting at the bottom where the horizontal
angle iron comes in. At this point the vertical plates meet one
another, and the edge formed is rounded over to fit the interior
of the bend of the horizontal angle iron so as to make the joint
tight. Draw half size.
The dimensions are as follows: angle irons 2-1/2 inches x 2-1/2
inches x 3/8 inch; plates 3/8 inch thick; rivets 11/16 inch
diameter and 2 inches pitch.
EXERCISE 10: _Gusset Stay._--In order that the flat ends of a
steam boiler may not be bulged out by the pressure of the steam
they are strengthened by means of stays. One form of boiler stay,
called a 'gusset stay,' is shown in fig. 8. This stay consists of
a strip of wrought-iron plate which passes in a diagonal direction
from the flat end of the boiler to the cylindrical shell. One end
of this plate is placed between and riveted to two angle irons
which are riveted to the shell of the boiler. A similar
arrangement connects the other end of the stay plate to the flat
end of the boiler. In this example the stay or gusset plate is 3/4
of an inch thick; the angle irons are 4 inches broad and 1/2 inch
thick. The rivets are 1 inch in diameter. The same figure also
illustrates the most common method of connecting the ends of a
boiler to the shell. The end plates are _flanged_ or bent over at
right angles and riveted to the shell as shown. The radius of the
inside curve at the angle of the flange is 1-1/4 inches. Draw this
example to a scale of 3 inches to 1 foot.
[Illustration: FIG. 6.]
[Illustration: FIG. 7.]
[Illustration: FIG. 8.]