[Illustration: Fig. 1442.]
[Illustration: Fig. 1443.]
For what may be termed the length measurements of lathe work it is
obvious that caliper gauges, such as shown in Fig. 1402, may be
employed. Since, however, these length measurements rarely require to be
so accurate as the diametrical measurements, the ordinary lineal rule is
very commonly employed in work not done under the standard gauge system.
It is obvious, however, that when a number of pieces are to be turned to
corresponding lengths, a strip of sheet iron, or of iron rod made to the
required length, may be employed; a piece of sheet iron filed to have
the necessary steps being used where there are several steps in the
work; but if the lineal measuring rule is used, and more than one
measurement of length is to be taken, some one point, as one end of the
work, should be taken wherefrom to measure all the other distances.
Suppose, for example, that Fig. 1442 represents a crank pin requiring to
have its end collar 1/4 inch thick, the part A 2 inches long, part B 3
inches long, collar C 1/2 inch thick, and the part D 7 inches long. If
the length of each piece were taken separately and independently of the
others, any errors of measurement would multiply; whereas, if some one
point be taken as a point wherefrom to measure all the other distances,
error is less liable to occur, while at the same time an error in one
measurement would not affect the correctness of the others. In the case
of the crank pin shown, the collar C would be the best point wherefrom
to take all the other measurements. First, it would require to be made
to its proper thickness, and the lengths of B, A, and the end collar
should be measured from its nearest radial face. The length of D should
then be measured from the same radial face, the thickness of the collar
being added to the required length of D, or D may be measured from the
nearest radial face of C, providing C be of its exact proper thickness.
In measuring the length of the taper part D, a correct measurement will
not be obtained by laying the rule along its surface, because that
surface does not lie parallel to its axis, hence it is necessary to
apply the measuring rule, as shown in Fig. 1443, in which S is a
straight-edge held firmly against the radial face of the crank pin (the
radial face being of course turned true), and R is the measuring rule
placed true with the axial line of the crank pin. Whenever the diameters
of the lengths to be measured vary, this mode of measuring must be
employed. On small work, or on short distances requiring to be very
exact, a gauge such as shown in Fig. 1444 at A may be employed, which
will not only give more correct results, but because it is more
convenient, as it can be conveniently held or tried to the work with one
hand while the other hand is applied to the feed screw handle to
withdraw the cutting tool at the proper moment, and to the feed nut to
unlock it and stop the feed.
[Illustration: Fig. 1444.]
[Illustration: Fig. 1445.]
On long work a wooden strip is the best, especially if the work has
varying diameters and a number of pieces of work require to be made
exactly alike. In Fig. 1445 S represents the wooden strip, and W the
work. The strip is marked across by lines representing the distances
apart the shoulders of the work require to be; thus the lines A, B, C,
D, E, F, G, represent the distances apart of the radial faces _a_, _b_,
_c_, _d_, _e_, _f_, _g_, on the work, and these lines will be in the
same plane as the shoulders if the latter are turned to correct lengths.
To compare the radial faces with the lines, a straight-edge must be held
to each successive shoulder (as already described) that is of smaller
diameter than the largest radial face on the work.
If the wooden strip be made the full length of the work the dog or clamp
driving the work will require to be removed every time the wooden gauge
is applied, and since the work must be turned end for end in the lathe
to be finished, it would be as well to let the length of the wood gauge
terminate before reaching the work driver, as, say, midway between E and
F.
When a lineal distance is marked by lines, and this distance is to be
transferred to another piece of work and marked thereon by lines, the
operation may be performed, for short distances or radii, by the common
compasses employed to mark circles, but for greater distances where
compasses would be cumbersome, the trammels are employed.
Fig. 1446 represents a pair of trammels made entirely of metal, and
therefore suitable for machinists' use, in which the points require to
be pressed to the work to mark the lines. A A represents a bar of square
steel; or for very long trammels wood may be used. B represents a head
fastened tightly to one end, and through B passes the leg or pointer C,
which is thus adjustable as to its projecting distance, as C can be
fastened in any position by the thumb-screw D. The head E is made to a
good sliding fit upon the bottom and two side faces of A A; but at the
top there is sufficient space to admit a spring, which passes through E.
F is the leg screwed into E, which is locked in position by the
thumb-screw G. The head E is thus adjustable along the whole length of
the bar or rod A A. The object of the spring is as follows:--If the head
E were made to fit the bar A A closely on all four sides, the burrs
raised upon the top side of the rod A A by the end of the thumb-screw G
would be likely to impede its easy motion. Then again, when the sliding
head E has worn a trifle loose upon the bar A A, and is loosened for
adjustment, it would be liable to hang on one side, and only to right
itself when the screw G brought it to a proper bearing upon the under
side of the bar A A, and thus tightening the head E would alter the
adjustment of the point. The spring, however, always keeps the lower
face of the square hole through E bearing evenly against the
corresponding face of the bar, so that tightening the screw G does not
affect the adjustment, and, furthermore, the end of the set-screw,
bearing against the spring instead of against the top of the rod,
prevents the latter from getting burred.
[Illustration: Fig. 1446.]
The flat place at I I is to prevent the burrs raised by the thumb-screw
end from preventing the easy sliding of leg C through B.
[Illustration: Fig. 1447.]
In some cases a gib is employed, as shown at A in Fig. 1447, instead of
a spring, the advantage being that it is less liable to come out of
place when moving the head along the bar.
The trammels should always be tried to the work in the same relative
position as that in which they were set, otherwise the deflection of the
bar may vitiate the correctness of the measurement; thus, if the rod or
bar stood vertical when the points were adjusted for distance to set
them to the required distance, it should also stand vertical upon the
work when applied to transfer that distance, otherwise the deflection of
the bar from its own weight will affect the correctness of the
operation. Again, when applied to the work the latter should be
suspended as nearly as convenient in the same position as the work will
occupy when erected to its place.
Thus, suppose the trammels be set to the crank pin centres of a
locomotive, then the bar will stand horizontally. Now the side rod, or
coupling rod, as it may be more properly termed, should be stood on edge
and should rest on its ends, because its bearings wherever it will rest
when on the engine are at the ends; thus the deflection of the trammel
rod will be in the same direction when applied to the work as it was
when applied to the engine, and the deflection of the coupling rod will
be in the same direction when tried by the trammel as when on the
engine. The importance of this may be understood when it is mentioned
that if the coupling rod be a long one, resting it on its side and
supporting it in the middle instead of at its ends will cause a
difference of 1/50th inch in its length.
[Illustration: Fig. 1448.]
Another lineal measuring gauge employed in the machine shop is shown in
Fig. 1448. It is employed to measure the distance between two faces, and
therefore in place of inside calipers, in cases where from the extreme
distance to be measured it would require the use of inside calipers too
large to be conveniently handled. Its application is more general upon
planing machine work than any other, although it is frequently used by
the lathe hand or turner, and by the vice hand and erector. It consists
of two legs A and B, held together by the screws C D, which screw into
nuts. These nuts should have a shoulder fitting into the slots in both
legs, so as to form a guide to the legs. The screws are set up so as to
just bind both legs together but leaving them free enough to move under
a slight friction. The gauge is then set to length by lightly striking
the ends E, and when adjusted the screws C D are screwed firmly home.
The ends E are rounded somewhat, as is shown, to prevent them from
swelling or burring by reason of the blows given to adjust them.
For striking circles we have the compasses or dividers, which are made
in various forms.
[Illustration: Fig. 1449.]
Thus, Fig. 1449 represents a pair of spring dividers, the bow spring at
the head acting to keep the points apart, and the screw and nut being
employed to close and to adjust them.
[Illustration: Fig. 1450.]
Another form is shown in Fig. 1450, the legs being operated by a right
and left-hand screw, which may be locked in position by the set-screw
shown.
For very small circles the fork scriber shown in Fig. 1451 is an
excellent tool, since it may be used with great pressure so as to cut a
deep line in the surface of the work. This tool is much used by boiler
makers, but is a very useful one for the machinist for a variety of
marking purposes, which will be described with reference to vice work.
For larger work we have the compasses, a common form of which is shown
in Fig. 1452, in which the leg A is slotted to receive the arc piece C,
which has a threaded stem passing through E, and is provided with a nut
at B; at D is a spring which holds the face of the nut B firmly against
the leg E; at A is a thumb-screw for securing the leg to the arm C. The
thumb-screw A being loosened, the compass legs may be rudely adjusted
for distance apart, and A is then tightened. The adjustment is finally
made by operating the nut B, which, on account of its fine thread,
enables a very fine adjustment to be easily made.
[Illustration: Fig. 1451.]
[Illustration: Fig. 1452.]
[Illustration: Fig. 1453.]
It is often very convenient to be able to set one leg of a pair of
dividers to be longer than the other, for which purpose a socket B, Fig.
1453, is provided, being pierced to receive a movable piece A, and split
so that by means of a set-screw C the movable piece A may be gripped or
released at pleasure.
[Illustration: Fig. 1454.]
For finding the centres of bodies or for testing the truth of a centre
already marked, the compass calipers shown in Fig. 1454, are employed.
It is composed of one leg similar to the leg of a pair of compasses,
while the other is formed the same as the leg of an inside caliper. The
uses of the compass calipers are manifold, the principal being
illustrated as follows:--
[Illustration: Fig. 1455.]
Let it be required to find the centre of a rectangular block, and they
are applied as in Fig. 1455, the curved leg being rested against the
edge and a mark being made with the compass leg. This being done from
all four sides of the work gives the centre of the piece.
[Illustration: Fig. 1456.]
In the case of a hole its bore must be plugged and the compass calipers
applied as in Fig. 1456.
[Illustration: Fig. 1457.]
For marking a line true with the axial line of a cylindrical body, we
have the instrument W in Fig. 1457, which is shown applied to a shaft S.
The two angles of the instrument are at a right angle one to another, so
that when placed on a cylindrical body the contact will cause the edge
of W to be parallel with the axis of the shaft. The edge is bevelled, as
shown, so that the lines of division of inches and parts may come close
to the work surface, and a scriber may be used to mark a line of the
required length. A scriber is a piece of steel wire having a hardened
sharp point wherewith to draw lines.
On account of the instrument W finding its principal application in
marking key seats upon shafts, it is termed the "key-seat rule."
[Illustration: Fig. 1458.]
For marking upon one surface a line parallel to another surface, the
scribing block or surface gauge shown in Fig. 1458 is employed. It
consists of a foot piece or stand D, carrying a stem. In the form shown
this stem contains a slot running centrally up it. Through this slot
passes a bolt whose diameter close to the head is larger than the width
of the slot, so that it is necessary to file flat places on the side of
the slot to permit the bolt to pass through it.
On the stem of the bolt close to the head, and between the bolt head and
the stem of the stand, passes the piece shown at F. This consists of a
piece of brass having a full hole through which the bolt passes clear up
to the bolt head. On the edge view there is shown a slot, and on each
side of the slot a section of a hole to receive a needle. A view of the
bolt is given at E, the flat place to fit the slot in the stem being
shown in dotted lines, and the space between the flat place and the bolt
head is where the piece of brass, shown in figure, passes. This piece of
brass being placed on the bolt, and the bolt being passed through the
slot in the stem, the needle is passed through the split in the brass,
and the thumb-nut is screwed on so that tightening up the thumb-nut
causes the needle to be gripped in the brass split in any position in
the length of the stem slot in which the bolt may be placed. The
advantage of this form over all others is that the needle may be made of
a simple piece of wire, and therefore very readily. Again, the piece of
brass carrying the needle may be rotated upon the pin any number of
consecutive rotations backwards and forwards, and there is no danger of
slacking the thumb-nut, because the needle is on the opposite side of
the stem to what the thumb-nut is, and the flat place prevents the bolt
from rotating. Furthermore, the needle can be rotated on the bolt for
adjustment for height without becoming loosened, whereas when the
thumb-nut is screwed up firmly the needle is held very fast indeed, and
finally all adjustments are made with a single thumb-nut.
The figure represents a view of this gauge from the bolt head and needle
side of the stem, the thumb-nut being on the opposite side.
This tool finds its field of application upon lathe work, planer work,
and, indeed, for one purpose or another upon all machine tools, and in
vice work and erecting, examples of its employment being given in
connection with all these operations.
[Illustration: Fig. 1459.]
Fig. 1459 represents a scribing block for marking the curves to which to
cut the ends of a cylindrical body that joins another, as in the case of
a [T]-pipe. It is much used by pattern-makers. In the figure A is a stem
on a stand E. A loose sleeve B slides on A carrying an arm C, holding a
pencil at D. A piece of truly surfaced wood or iron W, has marked on it
the line J. Two [V]s, G, G, receive the work P. Now, if the centres of
G, G and of the stand E all coincide with the line J then E will stand
central to P, and D may be moved by the hand round P, being allowed to
lift and fall so as to conform to the cylindrical surface of P, and a
line will be marked showing where to cut away the wood on that side, and
all that remains to do is to turn the work over and mark a similar line
diametrically opposite, the second line being dotted in at K.
[Illustration: Fig. 1460.]
The try square, Fig. 1460, is composed of a rectangular back F, holding
a blade, the edges of the two being at a right angle one to the other
and as straight as it is possible to make them. The form shown in the
figure is an [L]-square.
[Illustration: Fig. 1461.]
Fig. 1461 represents the [T]-square, whose blade is some distance from
the end of the back and is sometimes placed in the middle. When the
square edges are at a true right angle the square is said to be true or
square, the latter being a technical term meaning at practically a true
right angle.
The machinists' square is in fact a gauge whereby to test if one face
stands at a right angle to another. It is applied by holding one edge
firmly and fairly bedded against the work, while the other edge is
brought to touch at some part against the face to be tested.
If in applying a square it be pressed firmly into the corner of the
work, any error in the latter is apt to escape observation, because the
square will tilt and the error be divided between the two surfaces
tested. To avoid this the back should be pressed firmly against one
surface of the work and the square edge then brought down or up to just
touch the work, which it will do at one end only if the work surface is
out of square or not at a right angle to the face to which the square
back is applied.
[Illustration: Fig. 1462.]
An application of the [T]-square is shown in Fig. 1462, in which W is a
piece of work requiring to have the face A of the jaw C at a right angle
to the face B C. Sometimes the [L]-square is employed in conjunction
with a straight-edge in place of the [T]-square. This is usually done in
cases where the faces against which the square rests are so far apart as
to require a larger [T]-square than is at hand. It is obvious that if
the face A of the work is the one to be tested, the edge B is the part
pressed to the work; or per contra, if B C is the face to be tested, the
edge of the blade is pressed to the work.
[Illustration: Fig. 1463.]
The plane of the edges of a square should, both on the blade and on the
back, stand at a right angle to the side faces of the body or stock, and
the side of the blade should be parallel to the sides of the back and
not at an angle to either side, nor should it be curved or bent, because
if under these conditions the plane of the square edge is not applied
parallel with the surface of the work the square will not test the work
properly. This is shown in Fig. 1463, in which W is a piece of work, and
S a square having its blade bent or curved and applied slightly out of
the vertical, so that presuming the plane of the blade edge to be a
right angle to the stock or back of the square the plane of the blade
edge will not be parallel with the plane of the work, hence it touches
the work at the ends A B only, whereas if placed vertically the blade
edge would coincide with the work surface all the way along. It is
obvious then that by making the edge of the blade at a right angle,
crossways as well as in its length, to the stock, the latter will serve
as a guide to the eye in adjusting the surface of the blade edge
parallel to that of the work by placing the stock at a right angle to
the same.
[Illustration: Fig. 1464.]
There are three methods of testing the angle of a square blade to the
square back. The first is shown in Fig. 1464, in which A is a surface
plate having its edge a true plane. The square S is placed in the
position shown by full lines pressed firmly to the edge of the surface
plate and a fine line is drawn with a needle point on the face of the
surface plate, using the edge of the square blade as denoted by the
arrow C as a guide. The square is then turned over as denoted by the
dotted lines and the edge is again brought up to the line and the
parallelism of the edge with the line denotes the truth, for whatever
amount the blade may be out of true will be doubled in the want of
coincidence of the blade edge with the line.
[Illustration: Fig. 1465.]
A better plan is shown in Fig. 1465, in which A is the surface plate, B
a cylindrical piece of iron turned true and parallel in the lathe and
having its end face true and cupped as denoted by the dotted lines so as
to insure that it shall stand steadily and true. The surface of A and
the vertical outline of B forming a true right angle we have nothing to
do but make the square S true to them when placed in the position shown.
[Illustration: Fig. 1466.]
[Illustration: Fig. 1467.]
[Illustration: Fig. 1468.]
If we have two squares that are trued and have their edges parallel, we
may test them for being at a right angle by trying them together as in
Figs. 1466 and 1467, in which A, B, are the two squares which, having
their back edges pressed firmly together (when quite clean), must
coincide along the blade edges; this being so we may place them on a
truly surfaced plate as shown in Fig. 1468, in which S is one square and
S´ the other, P being the surface plate. Any want of truth in the right
angle will be shown doubled in amount by a want of coincidence of the
blade edges.
[Illustration: Fig. 1469.]
For some purposes, as for marking out work on a surface plate, it is
better that the square be formed of a single piece having the back and
blade of equal thickness, as shown in Fig. 1469, which represents a side
and edge view of an [L]- and [T]-square respectively.
[Illustration: Fig. 1470.]
For angles other than a right angle we have the bevel or bevel square
(as it is sometimes called), shown in Fig. 1470, A representing the
stock or back, and B the blade, the latter being provided with a slot so
that it may be extended to any required distance (within its scope) on
either side of the stock. C is the rivet, which is made sufficiently
tight to permit of the movement by hand of the blade, and yet it must
hold firmly enough to be used without moving in the stock. Instead of
the rivet C, however, a thumb-screw and nut may be employed, in which
case, after the blade is set to the required angle, it may be locked in
the stock by the thumb-screw.
Fig. 1471 represents a Brown and Sharpe bevel protractor, with a pivot
and thumb-nut in the middle of the back with a half-circle struck from
the centre of the pivot and marked to angular degrees. The pointer for
denoting the degrees of angle has also a thumb-screw and nut so that the
blade may, by loosening the pivot and pointer, be moved to project to
the required distance on either side of the back.
[Illustration: Fig. 1471.]
[Illustration: Fig. 1472.]
Swasey's improved protractor, however, is capable of direct and easy
application to the work, forming a draughtsman's protractor, and at the
same time a machinist's bevel or bevel square, while possessing the
advantage that there is no protruding back or set-screw to prevent the
close application of the blade to the work. This instrument is shown in
Fig. 1472. The blade A is attached to the circular piece D, the latter
being recessed into the square B B, and marked with the necessary
degrees of angle, as shown, while the mark F upon the square B serves as
an index point. The faces of A, B B, and D are all quite level, so that
the edges will meet the lines upon the work and obviate any liability to
error. The piece D is of the shape shown in section at G, which secures
it in B B, the fit being sufficient to permit of its ready adjustment
and retain it by friction in any required position. The dotted lines
indicate the blade as it would appear when set to an angle, the point E
being the centre of D, and hence that from which the blade A operates.
[Illustration: Fig. 1473.]
On account, however, of the numerous applications in machine work of the
hexagon (as, for instance, on the sides of both heads and nuts), a
special gauge for that angle is requisite, the usual form being shown in
Fig. 1473. The edges A, B, form a hexagon gauge, and edges C, D, form a
square, while the edge E serves as a straight-edge.
All these tools should be made of cast steel, the blades being made of
straight saw blade, so that they will not be apt to permanently set from
an ordinary accidental blow; while, on the other hand, if it becomes, as
it does at times, necessary to bend the blade over to the work, it will
resume its straightness and not remain bent.
For testing the straightness, in one direction only, of a surface the
straight-edge is employed. It consists in the small sizes of a piece of
steel whose edges are made straight and parallel one to the other. When
used to test the straightness of a surface without reference to its
alignment with another one, it is simply laid upon the work and sighted
by the eye, or it may have its edge coated with red marking, and be
moved upon the work so that its marking will be transferred to the high
spots upon the work. The marking will look of the darkest colour in the
places where the straight-edge bears the hardest. The most refined use
of the straight-edge is that of testing the alignment of one surface to
the other, and as this class of work often requires straight-edges of
great length, as six or ten feet, which if made of metal would bend of
its own weight, therefore they are made of wood.
[Illustration: Fig. 1474.]
Fig. 1474 represents an example of the use of straight-edge for
alignment purposes. It represents a fork and connecting rod, and it is
required to find if the side faces of the end B are in line with the
fork jaws. A straight-edge is held firmly against the side faces of B in
the two positions S and S´, and it is obvious that if they are in line
the other end will be equidistant from the jaw faces, at the two
measurements.
[Illustration: Fig. 1475.]
[Illustration: Fig. 1476.]
[Illustration: Fig. 1477.]
Figs. 1474, 1475, 1476, 1477, and 1478 represent the process of testing
the alignment of a link with a straight-edge. First to test if the
single eye E is in line with the double eye F at the other end, the
straight-edge is pressed against the face of E, as in Fig. 1475, and the
distance I is measured. The straight-edge is then applied on the other
side of E, as in Fig. 1476, and the distance H is measured, and it is
clear that if distances H and I are equal, then E is in line with the
double eye. To test if the double eye F is in line with the single eye
E, the straight-edge is pressed against the face of the double eye in
the positions shown in Figs. 1477 and 1478, and when distances J and K
measure equal the jaws of the double eye F are in line with those of the
single eye E.
[Illustration: Fig. 1478.]
[Illustration: Fig. 1479.]
[Illustration: Fig. 1480.]
[Illustration: Fig. 1481.]
[Illustration: Fig. 1482.]
[Illustration: Fig. 1483.]
It is obvious, however, that we have here tested the alignment in one
direction only. But to test in the other direction we may use a pair of
straight-edges termed winding strips, applying them as in Fig. 1479, to
test the stem, and as in Fig. 1480 to test the eye E, and finally
placing the winding strip C on the eye of F while strip D remains upon
E, as in Fig. 1480. The two strips are sighted together by the eye, as
is shown in Fig. 1481, in which S and S´´ are the strips laid upon a
connecting rod, their upper edges being level with the eye, hence if
they are not in line the eye will readily detect the error. Fig. 1482
represents an application to a fork ended connecting rod. Pattern-makers
let into their winding strips pieces of light-coloured wood as at C, C,
C, C, in Fig. 1483, so that the eye may be assisted in sighting them.
It is obvious that in using winding strips they should be parallel one
to the other; thus, for example, the ends A, B, in Fig. 1481, should be
the same distance apart as ends C, D.
If less than three straight-edges or parallel strips are to be trued
they must be trued to a surface plate or its equivalent, but if a pair
are to be made they should have the side faces made true, and be riveted
together so that their edges may be trued together, and equal width may
be more easily obtained. For this purpose copper rivets should be used,
because they are more readily removable, as well as less likely to
strain the work in the riveting.
By riveting the straight-edges together the surface becomes broader and
the file operates steadier, while the edges of the straight-edge are
left more square. Furthermore parallelism is more easily obtained as one
measurement at each end of the batch will test the parallelism instead
of having to measure each one separately at each end. If three
straight-edges are to be made they may be riveted together and filed as
true as may be with the testing conveniences at hand, but they should be
finally trued as described for the surface plate.
In using straight-edges to set work, the latter is often heated to
facilitate the setting, and in this case the straight-edge or parallel
strips should be occasionally turned upside down upon the work, for if
the heated work heats one side of the straightedge more than the other
the increased expansion of the side most heated will bend the
straight-edge or strips, and throw them out of true.
In applying a straight-edge to test work it must never be pressed to the
work surface, because in that case it will show contact with the work
immediately beneath the parts where such pressure is applied. Suppose,
for example, a true straight-edge be given a faint marking, and be
applied to a true surface, the straight-edge itself being true; then if
the hands are placed at each end of the straight-edge, and press it to
the work while the straight-edge is given motion, it will leave the
heaviest marks at and near the ends as though the work surface was
slightly hollow in its length; while were the hand pressure applied to
the middle of the length of the straight-edge the marks on the work
would show the heaviest in the middle as though the work surface were
rounding. This arises from the deflection due to the weakness of the
straight-edge.
For testing the truth of flat or plane surfaces the machinist employs
the surface plate or planometer. The surface plate is a plate or casting
having a true flat surface to be used as a test plate for other
surfaces. It is usually made of cast iron, and sometimes of chilled cast
iron or hardened cast steel, the surface in either of these two latter
cases being ground true because their hardness precludes the possibility
of cutting them with steel tools. A chilled or hardened surface plate
cannot, however, be so truly surfaced as one that is finished with
either the scraper or the file.
The shape of the surface plate is an element of the first importance,
because as even the strongest bars of metal deflect from their own
weight, it is necessary to shape the plate with a view to make this
deflection as small as possible in any given size and weight of plate.
In connection, also, with the shape we must consider the effect of
varying temperatures upon the metal, for if one part of the plate is
thinner than another it will, under an increasing temperature, heat more
rapidly, and the expansion due to the heating will cause that part to
warp the plate out of its normal form, and hence out of true. The amount
that a plate will deflect of its own weight can only be appreciated by
those who have had experience in getting up true surfaces, but an idea
may be had when it is stated that it can be shown that it is easily
detected, in a piece of steel three inches square and a foot long.
Now this deflection will vary in direction according to the points upon
which the plate rests. For instance, take two plates, clean them
properly, and rest one upon two pieces of wood, one piece under each
end, and then place another plate upon the lower one and its face will
show hollow, and, if the upper plate is moved backwards and forwards
laterally it will be found to move from the ends as centres of motion.
Then rest the lower plate upon a piece of wood placed under the middle
of its length, and we shall find that (if the plates are reasonably
true) the top one will move laterally with the middle of its length as a
centre of motion. Now although this method of testing will prove
deflection to exist, it will not show its amount, because the top plate
deflects to a certain extent, conforming itself to the deflection of the
lower one, and if the test is accurately made it will be found that the
two plates will contact at whatever points the lower one is supported.
If plates, tested in this manner, show each other to have contact all
along however the lower one is supported, it is because they are so
light that the upper one will readily bend to suit the deflection of the
lower one, and true work is, with such a plate, out of the question.
To obviate these difficulties the body of the plate is heavily ribbed,
and these ribs are so arranged as to be of equal lengths, and are made
equal in thickness to the plate, so that under variations of temperature
the ribs will not expand or contract more quickly or slowly than the
body of the plate, and the twisting that would accompany unequal
expansion is avoided.
[Illustration: Fig. 1484.]
In Fig. 1484 is shown the form of surface plate designed by Sir Joseph
Whitworth for plates to be rested upon their feet. The resting points of
the plate are small projections shown at A, B, and C. The object of this
arrangement of feet is to enable the plate to rest with as nearly as
possible an equal degree of weight upon each foot, the three feet
accommodating themselves to an uneven surface. It is obvious, however,
that more of the weight will fall upon C than upon A or B, because C
supports the whole weight at one end, while at the other end A and B
divide the weight.
[Illustration: Fig. 1485.]
Fig. 1485 shows the form of plate designed by Professor Sweet.
[Illustration: Fig. 1486.]
In Fig. 1486 is shown a pair of angle surface plates resting upon a flat
one. The angle plates may be used for a variety of purposes where it is
necessary to true a surface standing at a true right angle to another.
The best methods of making surface plates are as follows:--
The edges of the plates should be planed first, care being taken to make
them square and flat. The surfaces should then be planed, the plates
being secured to the planer _by the edges_, which will prevent as far as
possible the pressure necessary to hold them against the planing tool
cut from springing, warping, or bending the plates. Before the finishing
cut is taken, the plates or screws holding the surface plate should be
slackened back a little so as to hold them as lightly as may be, the
finishing cut being a very light one, and under these circumstances the
plates may be planed sufficiently true that one will lift the other from
the partial vacuum between them.
After the plates are planed, and before any hand work is done on them,
they should be heated to a temperature of at least 200° Fahr., so that
any local tension in the casting may be as far as possible removed.
[Illustration: Fig. 1487.]
Surface plates for long and narrow surfaces are themselves formed long
and narrow, as shown in Fig. 1487, which represents the straight-edge
surface plate made at Cornell University.
[Illustration: Fig. 1488.]
The Whitworth surfacing straight-edge, or long narrow surface plate, is
ribbed as in Fig. 1488, so as to give it increased strength in
proportion to its weight, and diminish its deflection from its own
weight. The lugs D are simply feet to rest it on.
Straight-edges are sometimes made of cast steel and trued on both edges.
These will answer well enough for small work, but if made of a length to
exceed about four feet their deflection from their own weight seriously
affects their reliability. The author made an experiment upon this point
with a very rigid surface plate six feet long, and three cast steel
straight-edges 6 feet long, 4-1/2 inches wide, and 1/2 inch thick. Both
edges of the straight-edges were trued to the surface plate until the
light was excluded from between them, while the bearing surface appeared
perfect; thin tissue paper was placed between the straight-edges and
the plate, and on being pulled showed an equal degree of tension. The
straight-edges were tried one with the other in the same way and
interchanged without any apparent error, but on measuring them it was
found that each was about 1/50 inch wider in the middle of its length
than at the ends, the cause being the deflection. They were finished by
filing them parallel to calipers, using the bearing marks produced by
rubbing them together and also upon the plate; but, save by the caliper
test, the improvement was not discernible.
In rubbing them together no pressure was used, but they were caused to
slide under their own weight only.
A separate and distinct class of gauge is used in practice to copy the
form of one piece and transfer it to another, so that the one may
conform to or fit the other. To accomplish this end, what are termed
male and female templates or gauges are employed. These are usually
termed templates, but their application to the work is termed gauging
it.
[Illustration: Fig. 1489.]
Suppose, for example, that a piece is to be fitted to the rounded corner
of a piece F, Fig. 1489, and the maker takes a piece of sheet metal A,
and cuts it out to the line B C D, leaving a female gauge E, which will
fit to the work F. We then make a male gauge G, and apply this to the
work, thus gauging the round corner.
[Illustration: Fig. 1490.]
Fig. 1490 represents small templates applied to a journal bearing, and
it is seen that we may make the template as at T, gauging one corner
only, or we may make it as at T´, thus gauging the length of the journal
as well as the corners.
[Illustration: Fig. 1491.]
[Illustration: Fig. 1492.]
Fig. 1491 represents a female gauge applied to the corner of a bearing
or brass for the above journal, it being obvious that the male and
female templates when put together will fit as in Fig. 1492.
For measuring the diameters of metal wire and the thickness of rolled
sheet metal, measuring instruments termed wire gauges and sheet metal
measuring machines are employed. A simple wire gauge is usually formed
of a piece of steel containing numerous notches, whose widths are equal
to the intended thickness to be measured in each respective notch. These
notches are marked with figures denoting the gauge-number which is
represented by the notch.
For wire, however, a gauge having holes instead of notches is sometimes
employed, the wire being measured by insertion in the hole, an operation
manifestly impracticable in the case of sheet metal.
In Fig. 1493 is shown one of Brown and Sharpe's notch wire-gauges, the
notches being arranged round the edge as shown:
[Illustration: Fig. 1493.]
The thickness of a given number of wire-gauge varies according to the
system governing the numbering of the gauge, which also varies with the
class of metal or wire for which the gauge has been adopted by
manufacturers. Thus, in the following table are given the gauge-numbers
and their respective sizes in decimal parts of an inch, as determined by
Holtzapffel in 1843, and to which sizes the Birmingham wire-gauge is
made. The following table gives the numbers and sizes of the Birmingham
wire-gauge.
BIRMINGHAM WIRE GAUGE.
-----+------++------+------++------+------++------+------
Mark.| Size.|| Mark.| Size.|| Mark.| Size.|| Mark.| Size.
-----+------++------+------++------+------++------+------
36 | .004 || 26 | .018 || 16 | .065 || 6 | .203
35 | .005 || 25 | .020 || 15 | .072 || 5 | .220
34 | .007 || 24 | .022 || 14 | .083 || 4 | .238
33 | .008 || 23 | .025 || 13 | .095 || 3 | .259
32 | .009 || 22 | .028 || 12 | .109 || 2 | .284
31 | .010 || 21 | .032 || 11 | .120 || 1 | .300
30 | .012 || 20 | .035 || 10 | .134 || 0 | .340
29 | .013 || 19 | .042 || 9 | .148 || 00 | .380
28 | .014 || 18 | .049 || 8 | .165 || 000 | .425
27 | .016 || 17 | .058 || 7 | .180 || 0000 | .454
-----+------++------+------++------+------++------+------
In this gauge it will be observed that the progressive wire gauge
numbers do not progress by a regular increment.
This gauge is sometimes termed the Stubs wire-gauge, Mr. Stubs being a
manufacturer of instruments whose notches are spaced according to the
Birmingham wire-gauge. Since, however, Mr. Stubs has also a wire-gauge
of his own, whose numbers and gauge-sizes do not correspond to those of
the Birmingham gauge, the two Stubs gauges are sometimes confounded. The
second Stubs gauge is employed for a special drawn steel wire, made by
that gentleman to very accurate gauge measurement for purposes in which
accuracy is of primary importance.
From the wear of the drawing dies in which wire is drawn, it is
impracticable, however, to attain absolute correctness of gauge
measurement. The dies are made to correct gauge when new, and when they
have become worn larger, to a certain extent, they are renewed. As a
result the average wire is slightly larger than the designated
gauge-number. To determine the amount of this error the Morse
Twist-Drill and Machine Company measured the wire used by them during an
extended period of time, the result being given in table No. 2, in which
the first column gives the gauge-number, the second column gives the
thickness of the gauge-number in decimal parts of an inch, and the third
column the actual size of the wire in decimal parts of an inch as
measured by the above Company.
DIAMETER OF STUBS'S DRAWN STEEL WIRE IN FRACTIONAL PARTS OF AN INCH.
-------+-------+--------++-------+-------+--------++-------+-------+--------
No. by |Stubs's|Measure-||No. by |Stubs's|Measure-||No. by |Stubs's|Measure-
Stubs's|Dimen- |ment by ||Stubs's|Dimen- |ment by ||Stubs's|Dimen- |ment by
wire- |sions. | Morse || wire- |sions. | Morse || wire- |sions. | Morse
gauge. | | Twist- ||gauge. | | Twist- ||gauge. | | Twist-
| | Drill || | | Drill || | | Drill
| | and || | | and || | | and
| |Machine || | |Machine || | |Machine
| | Co. || | | Co. || | | Co.
-------+-------+--------++-------+-------+--------++-------+-------+--------
1 | .227 | .228 || 23 | .153 | .154 || 45 | .081 | .082
2 | .219 | .221 || 24 | .151 | .152 || 46 | .079 | .080
3 | .212 | .213 || 25 | .148 | .150 || 47 | .077 | .079
4 | .207 | .209 || 26 | .146 | .148 || 48 | .075 | .076
5 | .204 | .206 || 27 | .143 | .145 || 49 | .072 | .073
6 | .201 | .204 || 28 | .139 | .141 || 50 | .069 | .070
7 | .199 | .201 || 29 | .134 | .136 || 51 | .066 | .067
8 | .197 | .199 || 30 | .127 | .129 || 52 | .063 | .064
9 | .194 | .196 || 31 | .120 | .120 || 53 | .058 | .060
10 | .191 | .194 || 32 | .115 | .116 || 54 | .055 | .054
11 | .188 | .191 || 33 | .112 | .113 || 55 | .050 | .052
12 | .185 | .188 || 34 | .110 | .111 || 56 | .045 | .047
13 | .182 | .185 || 35 | .108 | .110 || 57 | .042 | .044
14 | .180 | .182 || 36 | .106 | .106 || 58 | .041 | .042
15 | .178 | .180 || 37 | .103 | .104 || 59 | .040 | .041
16 | .175 | .177 || 38 | .101 | .101 || 60 | .039 | .040
17 | .172 | .173 || 39 | .099 | .100 || 61 | .038 | .039
18 | .168 | .170 || 40 | .097 | .098 || 62 | .037 | .038
19 | .164 | .166 || 41 | .095 | .096 || 63 | .036 | .037
20 | .161 | .161 || 42 | .092 | .094 || 64 | .035 | .036
21 | .157 | .159 || 43 | .088 | .089 || 65 | .033 | .035
22 | .155 | .156 || 44 | .085 | .086 || | |
-------+-------+--------++-------+-------+--------++-------+-------+--------
The following table represents the letter sizes of the same wire:--
LETTER SIZES OF WIRE.
A. 0.234 | J. 0.277 | S. 0.348
B. 0.238 | K. 0.281 | T. 0.358
C. 0.242 | L. 0.290 | U. 0.368
D. 0.246 | M. 0.295 | V. 0.377
E. 0.250 | N. 0.302 | W. 0.386
F. 0.257 | O. 0.316 | X. 0.397
G. 0.261 | P. 0.323 | Y. 0.404
H. 0.266 | Q. 0.332 | Z. 0.413
I. 0.272 | R. 0.339 |
By an Order in Council dated August 23rd, 1883, and which took effect on
March 1st, 1884, the standard department of the British Board of Trade
substituted for the old Birmingham wire-gauge the following:--
+-------------+--------------++---------------------------+
| Descriptive | Equivalents || Descriptive | Equivalents |
| number | in parts || number | in parts |
| B. W. G. | of an inch. || B. W. G. | of an inch. |
+-------------+--------------++-------------+-------------+
| No. | Inch. || No. | Inch. |
| 7/0 | 0.500 || 23 | 0.024 |
| 6/0 | .464 || 24 | .022 |
| 5/0 | .432 || 25 | .020 |
| 4/0 | .400 || 26 | .018 |
| 3/0 | .372 || 27 | .0164 |
| 2/0 | .348 || 28 | .0148 |
| 0 | .324 || 29 | .0136 |
| 1 | .300 || 30 | .0124 |
| 2 | .276 || 31 | .0116 |
| 3 | .252 || 32 | .0108 |
| 4 | .232 || 33 | .0100 |
| 5 | .212 || 34 | .0092 |
| 6 | .192 || 35 | .0084 |
| 7 | .176 || 36 | .0076 |
| 8 | .160 || 37 | .0068 |
| 9 | .144 || 38 | .0060 |
| 10 | .128 || 39 | .0052 |
| 11 | .116 || 40 | .0048 |
| 12 | .104 || 41 | .0044 |
| 13 | .092 || 42 | .0040 |
| 14 | .080 || 43 | .0036 |
| 15 | .072 || 44 | .0032 |
| 16 | .064 || 45 | .0028 |
| 17 | .056 || 46 | .0024 |
| 18 | .048 || 47 | .0020 |
| 19 | .040 || 48 | .0016 |
| 20 | .036 || 49 | .0012 |
| 21 | .032 || 50 | .0010 |
| 22 | .028 || | |
+-------------+--------------++-------------+-------------+
[Illustration: Fig. 1494.]
[Illustration: Fig. 1495.]
The gauge known as the American Standard Wire-Gauge was designed by
Messrs. Brown and Sharpe to correct the discrepancies of the old
Birmingham wire-gauge by establishing a regular proportion of the
thirty-nine successive steps between the 0000 and 36 gauge-number of
that gauge. In the American Standard (which is also called the Brown and
Sharpe gauge) the value of 0.46 or 46/100 has been taken as that for
0000 or the largest dimension of the gauge. Then by successive and
uniform decrements, each number following being obtained from
multiplying its predecessor by 0.890522 (which is the same thing as
deducting 10.9478 per cent.), the final value for number 36 is reached
at 0.005, which corresponds with number 35 of the Birmingham wire-gauge.
The principle of the gauge is shown in Fig. 1495, which represents a
gauge for jewelers, having an angular aperture with the gauge-numbers
marked on the edge, the lines and numbers being equidistant.
The advantage of this system is that the instrument is easy to produce,
the difference between any two gauge-numbers being easily found by
calculation; and the gauge is easy to originate, since the opening,
being of the proper width at the open end, the sides terminating at the
proper distance and being made straight, the intermediate gauge-sizes
may be accurately marked by the necessary number of equidistant lines.
Wire, to be measured by such a gauge, is simply inserted into and passed
up the aperture until it meets the sides of the same, which gives the
advantage that the size of the wire may be obtained, even though its
diameter vary from a gauge-number. This could not be done with a gauge
in which each gauge-number and size is given in a separate aperture or
notch. A comparison between the Brown and Sharpe and the Birmingham
wire-gauge is shown in Fig. 1494, in which a piece of wire is inserted,
showing that No. 15 by the Birmingham gauge is No. 13 by the Brown and
Sharpe gauge.
The gauge-numbers and sizes of the same in decimal parts of an inch, of
the American standard or Brown and Sharpe gauge, are given in the table
following:--
------+--------------------------++------+--------------------------
|American or New Standard. || | American or New Standard.
+--------------------------++ +------------+-------------
No. of|Size of each| Difference ||No. of|Size of each| Difference
Wire- | number in | between ||Wire- | number in | between
Gauge.| decimal | consecutive ||Gauge.| decimal | consecutive
| parts of | numbers in || | parts of | numbers in
| an inch. |decimal parts|| | an inch. |decimal parts
| | of an inch. || | | of an inch.
------+------------+-------------++------+------------+-------------
0000 | .460 | ---- || 19 | .03589 | .00441
000 | .40964 | .05036 || 20 | .03196 | .00393
00 | .36480 | .04484 || 21 | .02846 | .00350
0 | .32495 | .03994 || 22 | .02535 | .00311
1 | .28930 | .03556 || 23 | .02257 | .00278
2 | .25763 | .03167 || 24 | .0201 | .00247
3 | .22942 | .02821 || 25 | .0179 | .00220
4 | .20431 | .02511 || 26 | .01594 | .00196
5 | .18194 | .02237 || 27 | .01419 | .00174
6 | .16202 | .01992 || 28 | .01264 | .00155
7 | .14428 | .01774 || 29 | .01126 | .00138
8 | .12849 | .01579 || 30 | .01002 | .00123
9 | .11443 | .01406 || 31 | .00893 | .00110
10 | .10189 | .01254 || 32 | .00795 | .00098
11 | .09074 | .01105 || 33 | .00708 | .00087
12 | .08081 | .00993 || 34 | .0063 | .00078
13 | .07196 | .00885 || 35 | .00561 | .00069
14 | .06408 | .00788 || 36 | .005 | .00061
15 | .05707 | .00702 || 37 | .00445 | .00055
16 | .05082 | .00625 || 38 | .00396 | .00049
17 | .04525 | .00556 || 39 | .00353 | .00043
18 | .0403 | .00495 || 40 | .00314 | .00039
------+------------+-------------++------+------------+-------------
This gauge is now the standard by which rolled sheet brass and seamless
brass tubing is made in the United States. It is also sometimes used as
a gauge for the copper wire used for electrical purposes, being termed
the American Standard; but unless the words "American Standard" are
employed, the above wire is supplied by the Birmingham wire-gauge
numbers. The brass wire manufacturers have not yet adopted the Brown and
Sharpe gauge; hence, for brass wire the Birmingham gauge is the
standard.
Gauges having simple notches are not suitable for measuring accurately
the thickness of metal, because the edges of the sheets or plates
frequently vary from the thickness of the body of the plate. This may
occur from the wear of the rolls employed to roll out the sheet, or
because the sheets have been sheared to cut them to the required width,
or to remove cracks at the edges, which shearing is apt to form a burr
or projection on one side of the edge, and a slight depression on the
other.
Again, a gauge formed by a notch requires to slide over the metal of the
plate, and friction and a wear causing an enlargement of the notch
ensues, which destroys the accuracy of the gauge. To avoid this source
of error the form of gauge that was shown in Fig. 1370 may be used, it
having the further advantage that it will measure thicknesses
intermediate between the sizes of two contiguous notches, thus measuring
the actual thickness of the sheet when it is not to any accurate sheet
metal gauge thickness.
It is to be observed that in the process of rolling, the sheet is
reduced from a greater to a lesser thickness, hence the gauge will not
pass upon the plate until the latter is reduced to its proper thickness.
In applying the gauge, therefore, there is great inducement for the
workman to force the gauge on to the sheet, in order to ascertain how
nearly the sheet is to the required size, and this forcing process
causes rapid wear to the gauge.
It follows, therefore, that a gauge should in no case be forced on, but
should be applied lightly and easily to the sheet to prevent wear. Here
may be mentioned another advantage of the Brown and Sharpe gauge, in
that its gauge-number measurements being uniform, it may be more readily
known to what extent a given plate varies from its required gauge
thickness.
Suppose, for example, a sheet requiring to be of Number 1 Birmingham
gauge is above the required thickness, but will pass easily through the
0 notch of the gauge, the excessive variation of those two gauge numbers
(over the variations between other consecutive numbers of the gauge)
leaves a wider margin in estimating how much the thickness is excessive
than would be the case in using the Brown and Sharpe gauge. Indeed, if
the edge of the plate be of uniform thickness with the body of the
plate, the variation from the required thickness may be readily
ascertained by a Brown and Sharpe gauge, by the distance the plate will
pass up the aperture beyond the line denoting the 0 gauge number, or by
the distance it stands from the 1 on the gauge when passed up the
aperture until it meets both sides of the same.
In addition to these standard gauges, some firms in the United States
employ a standard of their own; the principal of these are given in
comparison with others in the table following.
DIMENSIONS OF SIZES, IN DECIMAL PARTS OF AN INCH.
------+---------+--------+----------+---------+---------+------------
Number| American|Birming-| Washburn | Trenton | G. W. |Old English,
of | or Brown| ham, | & Moen |Iron Co.,|Prentiss,| from Brass
Wire | & | or | Mfg. Co.,| Trenton,| Holyoke,| Manu-
Gauge.| Sharpe. |Stubs's.|Worcester,| N. J. | Mass. | facturers'
| | | Ms. | | | List.
------+---------+--------+----------+---------+---------+------------
000000| ---- | ---- | .46 | ---- | ---- | ----
00000| ---- | ---- | .43 | .45 | ---- | ----
0000| .46 | .454 | .393 | .4 | ---- | ----
000| .40964 | .425 | .362 | .36 | .3586 | ----
00| .3648 | .38 | .331 | .33 | .3282 | ----
0| .32495 | .34 | .307 | .305 | .2994 | ----
1| .2893 | .3 | .283 | .285 | .2777 | ----
2| .25763 | .284 | .263 | .265 | .2591 | ----
3| .22942 | .259 | .244 | .245 | .2401 | ----
4| .20431 | .238 | .225 | .225 | .223 | ----
5| .18194 | .22 | .207 | .205 | .2047 | ----
6| .16202 | .203 | .192 | .19 | .1885 | ----
7| .14428 | .18 | .177 | .175 | .1758 | ----
8| .12849 | .165 | .162 | .16 | .1605 | ----
9| .11443 | .148 | .148 | .145 | .1471 | ----
10| .10189 | .134 | .135 | .13 | .1351 | ----
11| .090742 | .12 | .12 | .1175 | .1205 | ----
12| .080808 | .109 | .105 | .105 | .1065 | ----
13| .071961 | .095 | .092 | .0925 | .0928 | ----
14| .064084 | .083 | .08 | .08 | .0816 | .083
15| .057068 | .072 | .072 | .07 | .0726 | .072
16| .05082 | .065 | .063 | .061 | .0627 | .065
17| .045257 | .058 | .054 | .0525 | .0546 | .058
18| .040303 | .049 | .047 | .045 | .0478 | .049
19| .03539 | .042 | .041 | .039 | .0411 | .04
20| .031961 | .035 | .035 | .034 | .0351 | .035
21| .028462 | .032 | .032 | .03 | .0321 | .0315
22| .025347 | .028 | .028 | .027 | .029 | .0295
23| .022571 | .025 | .025 | .024 | .0261 | .027
24| .0201 | .022 | .023 | .0215 | .0231 | .025
2S| .0179 | .02 | .02 | .019 | .0212 | .023
26| .01594 | .018 | .018 | .018 | .0194 | .0205
27| .014195 | .016 | .017 | .017 | .0182 | .01875
28| .012641 | .014 | .016 | .016 | .017 | .0165
29| .011257 | .013 | .015 | .015 | .0163 | .0155
30| .010025 | .012 | .014 | .014 | .0156 | .01375
31| .008928 | .01 | .0135 | .013 | .0146 | .01225
32| .00795 | .009 | .013 | .012 | .0136 | .01125
33| .00708 | .008 | .011 | .011 | .013 | .01025
34| .006304 | .007 | .01 | .01 | .0118 | .0095
35| .005614 | .005 | .0095 | .009 | .0109 | .009
36| .005 | .004 | .009 | .008 | .01 | .0075
37| .004453 | ---- | .0085 | .00725 | .0095 | .0065
38| .003965 | ---- | .008 | .0065 | .009 | .00575
------+---------+--------+----------+---------+---------+------------
In the Whitworth wire-gauge, the mark or number on the gauge simply
denotes the number of 1/1000ths of an inch the wire is in diameter; thus
Number 1 on the gauge is 1/1000 inch, Number 2 is 2/1000ths inch in
diameter, and so on.
Below is given the Washburn and Moen Manufacturing Company's music
wire-gauge.
SIZES OF THE NUMBERS OF STEEL MUSIC WIRE-GAUGE.
+--------+------------------++--------+------------------+
| No. of | Size of each No. || No. of | Size of each No. |
| Gauge. | in decimal parts || Gauge. | in decimal parts |
| | of an inch. || | of an inch. |
+--------+------------------++--------+------------------+
| 12 | .0295 || 21 | .0461 |
| 13 | .0311 || 22 | .0481 |
| 14 | .0325 || 23 | .0506 |
| 15 | .0343 || 24 | .0547 |
| 16 | .0359 || 25 | .0585 |
| 17 | .0378 || 26 | .0626 |
| 18 | .0395 || 27 | .0663 |
| 19 | .0414 || 28 | .0719 |
| 20 | .043 || ---- | ---- |
+--------+------------------++--------+------------------+
These sizes are those used by the Washburn and Moen Manufacturing
Company, of Worcester, Mass., manufacturers of steel music wire.
In the following table is the French Limoges wire-gauge.
-------+-----------+-------++--------+-----------+------
Number | Diameter, | Inch. || Number | Diameter, | Inch.
on | milli- | || on | milli- |
gauge. | mètre. | || gauge. | mètre. |
-------+-----------+-------++--------+-----------+------
0 | .39 | .0154 || 13 | 1.91 | .0725
1 | .45 | .0177 || 14 | 2.02 | .0795
2 | .56 | .0221 || 15 | 2.14 | .0843
3 | .67 | .0264 || 16 | 2.25 | .0886
4 | .79 | .0311 || 17 | 2.84 | .112
5 | .90 | .0354 || 18 | 3.40 | .134
6 | 1.01 | .0398 || 19 | 3.95 | .156
7 | 1.12 | .0441 || 20 | 4.50 | .177
8 | 1.24 | .0488 || 21 | 5.10 | .201
9 | 1.35 | .0532 || 22 | 5.65 | .222
10 | 1.46 | .0575 || 23 | 6.20 | .244
11 | 1.68 | .0661 || 24 | 6.80 | .268
12 | 1.80 | .0706 || | |
-------+-----------+-------++--------+-----------+------
The following table gives the Birmingham wire-gauge for rolled sheet
silver and gold.
+---------+------------++---------+------------+
| Gauge | Thickness. || Gauge | Thickness. |
| number. | || number. | |
+---------+------------++---------+------------+
| | Inch. || | Inch. |
| 1 | .004 || 19 | .064 |
| 2 | .005 || 20 | .067 |
| 3 | .008 || 21 | .072 |
| 4 | .010 || 22 | .074 |
| 5 | .013 || 23 | .077 |
| 6 | .013 || 24 | .082 |
| 7 | .015 || 25 | .095 |
| 8 | .016 || 26 | .103 |
| 9 | .019 || 27 | .113 |
| 10 | .024 || 28 | .120 |
| 11 | .029 || 29 | .124 |
| 12 | .034 || 30 | .126 |
| 13 | .036 || 31 | .133 |
| 14 | .041 || 32 | .143 |
| 15 | .047 || 33 | .145 |
| 16 | .051 || 34 | .148 |
| 17 | .057 || 35 | .158 |
| 18 | .061 || 36 | .167 |
+---------+------------++---------+------------+
The following table gives the gauge thickness of Russia sheet iron,[25]
the corresponding numbers by Birmingham wire gauge, and the thicknesses
in decimal parts of an inch.
[25] This iron comes in sheets 28 × 56 inches = 10.88 square feet of
area.
+----------+------------+-------------------+
| Russia | Birmingham | Thickness in |
| gauge | wire-gauge | decimal |
| number. | number. | parts of an inch. |
+----------+------------+-------------------+
| 7 | 29 | .013 |
| 8 | 28 | .014 |
| 9 | 27 | .016 |
| 10 | 26 | .018 |
| 11 | 25 | .020 |
| 12 | 24-1/2 | .021 |
| 13 | 24 | .022 |
| 14 | 23-1/4 | ---- |
| 15 | 22-3/8 | ---- |
| 16 | 21-1/2 | ---- |
+----------+------------+-------------------+
The following table gives the gauge numbers to which galvanized iron is
made.[26]
[26] Galvanized iron is made to the Birmingham wire-gauge, the
thickness includes the galvanizing, the sheets being rolled thinner to
allow for it.
+---------+------------++---------+------------+
| Gauge | Thickness. || Gauge | Thickness. |
| number. | || number. | |
+---------+------------++---------+------------+
| | Inch. || | Inch. |
| 14 | .083 || 23 | .025 |
| 16 | .065 || 24 | .022 |
| 17 | .058 || 25 | .02 |
| 18 | .049 || 26 | .018 |
| 19 | .042 || 27 | .016 |
| 20 | .035 || 28 | .014 |
| 21 | .032 || 29 | .013 |
| 22 | .028 || | |
+---------+------------++---------+------------+
In the following table is given the American gauge sizes and their
respective thicknesses for sheet zinc.
--------------------------------++--------------------------------
Gauge and Thickness. || Gauge and Thickness.
-------+-----------+------------++-------+-----------+------------
Number.|Approximate|Thickness in||Number.|Approximate|Thickness in
|Birmingham |fractions of|| |Birmingham |fractions of
|wire-gauge.| an inch. || |wire-gauge.| an inch.
-------+-----------+------------++-------+-----------+------------
1 | ---- | 0.0039 || 16 | ---- | 0.0447
5 | ---- | 0.0113 || 17 | ---- | 0.0521
6 | ---- | 0.0132 || 18 | ---- | 0.0596
7 | ---- | 0.0150 || 19 | ---- | 0.0670
8 | 28 | 0.0169 || 20 | ---- | 0.0744
9 | 27 | 0.0187 || 21 | ---- | 0.0818
10 | 26 | 0.0224 || 22 | ---- | 0.0892
11 | 25 | 0.0261 || 23 | ---- | 0.0966
12 | 24 | 0.0298 || 24 | ---- | 0.1040
13 | ---- | 0.0336 || 25 | ---- | 0.1114
14 | ---- | 0.0373 || 26 | ---- | 0.1189
15 | ---- | 0.0410 || | |
-------+-----------+------------++-------+-----------+------------
The Belgian sheet zinc gauge is as follows:
+---------+-------------++---------+-------------+
| Gauge | Thickness in|| Gauge | Thickness in|
| number. |decimal parts|| number. |decimal parts|
| | of an inch. || | of an inch. |
+---------+-------------++---------+-------------+
| 1 | .004 || 14 | .037 |
| 2 | .006 || 15 | .041 |
| 3 | .008 || 16 | .045 |
| 4 | .009 || 17 | .052 |
| 5 | .011 || 18 | .059 |
| 6 | .013 || 19 | .067 |
| 7 | .015 || 20 | .074 |
| 8 | .017 || 21 | .082 |
| 9 | .019 || 22 | .089 |
| 10 | .022 || 23 | .097 |
| 11 | .026 || 24 | .104 |
| 12 | .030 || 25 | .111 |
| 13 | .034 || 26 | .120 |
+---------+-------------++---------+-------------+
The gauge sizes of the bores of rifles are given in the following
table,[27] in which the first column gives the proper gauge diameter of
bore, and the second the actual diameter containing the errors found to
exist from errors of workmanship. The standard diameters are supposed to
be based upon the number of spherical bullets to the pound weight, if of
the same diameter as the respective gauge sizes.
[27] From _The English Mechanic_.
No. of Diameter of Bore.
Gauge.
4 varies from 1.052 to 1.000
6 " .919 " .900
8 " .835 " .820
10 " .775 " .760
12 " .729 " .750
14 " .693 " .680
16 " .662 " .650
20 " .615 " .610
24 " .579 " .577
28 " .550 " .548
The following table gives the result of some recent experiments made by
Mr. David Kirkaldy, of London, to ascertain the tensile strength and
resistance to torsion of wire made of various materials:
+-----------------------+--------------------------+
| |Pulling stress per sq. in.|
| Kind of wire tested. +-------------+------------+
| | Unannealed. | Annealed. |
+-----------------------+-------------+------------+
| | Pounds. | Pounds. |
|Copper | 63,122 | 37,002 |
|Brass | 81,156 | 51,550 |
|Charcoal iron | 65,834 | 46,160 |
|Coke iron | 64,321 | 61,294 |
|Steel | 120,976 | 74,637 |
|Phosphor bronze, No. 1 | 159,515 | 58,853 |
| " No. 2 | 151,119 | 64,569 |
| " No. 3 | 139,141 | 54,111 |
| " No. 4 | 120,900 | 53,381 |
+-----------------------+-------------+------------+
+-----------------------+------------+----------------------+
| | Ultimate | No. of twists in |
| Kind of wire tested. |extension in| 5 inches. |
| | per cent. +-----------+----------+
| | Annealed. |Unannealed.| Annealed.|
+-----------------------+------------+-----------+----------+
|Copper | 34.1 | 86.8 | 96 |
|Brass | 36.5 | 14.7 | 57 |
|Charcoal iron | 28 | 48 | 87 |
|Coke iron | 17 | 26 | 44 |
|Steel | 10.9 | [28] | 79 |
|Phosphor bronze, No. 1 | 46.6 | 13.3 | 66 |
| " No. 2 | 42.8 | 15.8 | 60 |
| " No. 3 | 44.9 | 17.3 | 53 |
| " No. 4 | 42.4 | 13 | 124 |
+-----------------------+------------+-----------+----------+
[28] Of the eight pieces of steel tested, three stood from forty to
forty-five twists, and five stood one and a half to four twists.
The following, on some experiments upon the elasticity of wires, is from
the report of a committee read before the British Association at
Sheffield, England.
"The most important of these experiments form a series that have been
made on the elastic properties of very soft iron wire. The wire used was
drawn for the purpose, and is extremely soft and very uniform. It is
about No. 20 B.W.G., and its breaking weight, tested in the ordinary
way, is about 45 lbs. This wire has been hung up in lengths of about 20
ft., and broken by weights applied, the breaking being performed more or
less slowly.
"In the first place some experiments have been tried as to the smallest
weight which, applied very cautiously and with precautions against
letting the weight run down with sensible velocity, will break the wire.
These experiments have not yet been very satisfactorily carried out, but
it is intended to complete them.
"The other experiments have been carried out in the following way: It
was found that a weight of 28 lbs. does not give permanent elongation to
the wire taken as it was supplied by the wire drawer. Each length of the
wire, therefore, as soon as it was hung up for experiment, was weighted
with 28 lbs., and this weight was left hanging on the wire for 24 hours.
Weights were then added till the wire broke, measurements as to
elongation being taken at the same time. A large number of wires were
broken with equal additions of weight, a pound at a time, at intervals
of from three to five minutes--care being taken in all cases, however,
not to add fresh weight if the wire could be seen to be running down
under the effect of the weight last added. Some were broken with weights
added at the rate of 1 lb. per day, some with 3/4 lb. per day, and some
with 1/2 lb. per day. One experiment was commenced in which it was
intended to break the wire at a very much slower rate than any of these.
It was carried on for some months, but the wire unfortunately rusted,
and broke at a place which was seen to be very much eaten away by rust,
and with a very low breaking weight. A fresh wire has been suspended,
and is now being tested. It has been painted with oil, and has now been
under experiment for several months.
"The following tables will show the general results of these
experiments. It will be seen, in the first place, that the prolonged
application of stress has a very remarkable effect in increasing the
strength of soft iron wire. Comparing the breaking weights for the wire
quickly broken with those for the same wire slowly broken, it will be
seen that in the latter case the strength of the wire is from two to ten
per cent. higher than in the former, and is on the average about five or
six per cent. higher. The result as to elongation is even more
remarkable, and was certainly more unexpected. It will be seen from the
tables that, in the case of the wire quickly drawn out, the elongation
is on the average more than three times as great as in the case of the
wire drawn out slowly. There are two wires for which the breaking
weights and elongations are given in the tables, both of them 'bright'
wires, which showed this difference very remarkably. They broke without
showing any special peculiarity as to breaking weight, and without known
difference as to treatment, except in the time during which the
application of the breaking weight was made. One of them broke with
44-1/4 lbs., the experiment lasting one hour and a half; the other with
47 lbs., the time occupied in applying the weight being 39 days. The
former was drawn out by 28.5 per cent. on its original length, the
latter by only 4.79 per cent.
"It is found during the breaking of these wires that the wire becomes
alternately more yielding and less yielding to stress applied. Thus from
weights applied gradually between 28 lbs. and 31 lbs. or 32 lbs., there
is very little yielding, and very little elongation of the wire. For
equal additions of weight between 33 lbs. and about 37 lbs. the
elongation is very great. After 37 lbs. have been put on, the wire seems
to get stiff again, till a weight of about 40 lbs. has been applied.
Then there is a rapid running down till 45 lbs. has been reached. The
wire then becomes stiff again, and often remains so till it breaks. It
is evident that this subject requires careful investigation."
TABLES SHOWING THE BREAKING OF SOFT IRON WIRES AT DIFFERENT SPEEDS.
I.--WIRE QUICKLY BROKEN.
+------------------------+-----------+---------------+
| | Breaking | Per cent. of |
| Rate of adding weight. | weight in | elongation on |
| | pounds. | original |
| | | length. |
+------------------------+-----------+---------------+
| _Dark Wire._[29] | | |
| 0-1/4 lb. per minute | 45 | 25.4 |
| 1 " 5 minutes | 45-1/4 | 25.9 |
| " 5 " | 45-1/4 | 24.9 |
| " 4 " | 44-1/4 | 24.58 |
| " 3 " | 44-1/4 | 24.88 |
| " 3 " | 45-1/4 | 29.58 |
| " 5 " | 44-1/4 | 27.78 |
| _Bright Wire._[29] | | |
| 1 lb. per 5 minutes | 44-1/4 | 28.5 |
| " 5 " | 44-1/4 | 27.0 |
| " 4 " | 44-1/4 | 27.1 |
+------------------------+-----------+---------------+
[29] The wire used was all of the same quality and gauge, but the
"dark" and "bright" wire had gone through slightly different
processes for the purpose of annealing.
II.--WIRE SLOWLY BROKEN.
+--------------------+------------+--------------------+
| Weight added and | Breaking | Per cent. of |
| number of | weight in | elongation on |
| experiment. | pounds. | original length. |
+--------------------+------------+--------------------+
| 1. 1 lb. per day | 48 | 7.58 |
| 2. " " | 46 | 8.13 |
| 3. " " | 47 | 7.05 |
| 4. " " | 47 | 6.51 |
| 5. " " | 47 | 8.62 |
| 6. " " | 47 | 5.17 |
| 7. " " | 46 | 5.50 |
| 8. " " | 47 | 6.92 bright wire |
| 1. 3/4 lb. per day | 49 | 8.50 |
| 2. " " | 48-1/4 | 8.81 |
| 3. " " | Broken by accident. |
| 4. " " | 46 | 7.55 |
| 5. " " | 46 | 6.41 |
| 6. " " | 45-1/2 | 6.62 |
| 1. 1/2 lb. per day | 48 | 8.26 |
| 2. " " | 50 | 8.42 |
| 3. " " | 49 | 7.18 |
| 4. " " | 47 | 4.79} |
| 5. " " | 46-1/2 | 6.00} bright wires |
+--------------------+------------+--------------------+
The American Standard diameters of solid drawn or seamless brass and
copper tube are as in the following table.
+----------+-----------------+---------------+---------------+
| Outside |Thickness Stubs's| Weight per | Weight per |
|diameter. | wire-gauge. | running foot. | running foot. |
| | | Brass tubes. | Copper tubes. |
+----------+-----------------+---------------+---------------+
| 5/8 | 18 | 3/8 | 3/8 |
| 3/4 | 17 | 1/2 | 1/2 |
| 13/16 | 17 | 9/16 | 9/16 |
| 7/8 | 17 | 5/8 | 5/8 |
| 15/16 | 16 | 11/16 | 11/16 |
| 1 | 16 | 3/4 | 3/4 |
| 1-1/8 | 16 | 7/8 | 7/8 |
| 1-1/4 | 12 and 14 | 1-1/4 | 1-1/4 |
| 1-3/8 | 12 " 14 | 1-3/8 | 1-3/8 |
| 1-1/2 | 12 " 14 | 1-1/2 | 1-6/10 |
| 1-5/8 | 12 " 14 | 1-5/8 | 1-7/10 |
| 1-3/4 | 12 " 14 | 1-3/4 | 1-8/10 |
| 1-13/16 | 12 " 14 | 1-13/16 | 1-9/10 |
| 1-7/8 | 12 " 14 | 1-7/8 | 1-15/16 |
| 1-15/16 | 12 " 14 | 2 | 2-1/10 |
| 2 | 12 " 14 | 2-1/8 | 2-1/4 |
| 2-1/8 | 12 " 14 | 2-1/4 | 2-3/8 |
| 2-1/4 | 12 " 14 | 2-3/8 | 2-1/3 |
| 2-3/8 | 12 " 14 | 2-1/2 | 2-2/3 |
| 2-1/2 | 11 " 13 | 2-3/4 | 3 |
| 2-5/8 | 11 " 13 | 3 | 3-1/8 |
| 2-3/4 | 11 " 13 | 3-1/8 | 3-1/4 |
| 2-7/8 | 11 " 13 | 3-1/4 | 3-3/8 |
| 3 | 11 " 13 | 3-3/8 | 3-1/2 |
| 3-1/8 | 11 " 13 | 3-1/2 | 3-3/4 |
| 3-1/4 | 11 " 13 | 3-7/8 | 4-1/8 |
| 3-3/8 | 11 " 13 | 4-1/8 | 4-1/4 |
| 3-1/2 | 11 " 13 | 4-1/4 | 4-3/8 |
| 4 | 11 " 13 | 5 | 5-1/4 |
| 4-1/4 | 11 " 13 | 6 | 6-1/2 |
| 5 | 10 " 12 | 7 | 8 |
| 6 | 10 " 12 | 9 | 10 |
+----------+-----------------+---------------+---------------+