upright plate _A_ and the reversible anti-friction sliding jaws _O U V
X_. The upright plate _A_ is attached to the slide _D_ in such a way
that it may be readily raised or lowered, or adjusted in any other
direction at pleasure; and may be set with either side facing the
lathe-head. The sliding jaws are made of phosphor bronze anti-friction
metal and four sets, of three in a set, are furnished with each
attachment, as shown at _O_, _U_, _V_, _X_, the forms differing so
they may be adapted to the various kinds of watch work, and they are
operated in radial grooves in the upright plate _A_ by means of the
rotating lever _L_, which moves the three jaws in and out, to and from
the center, or opens and closes them in perfect unison. One set of
jaws may be withdrawn and another set substituted therefor in a few
moments. With each change of the jaws, however, the plate _A_ requires
readjustment, but this too, may be done in a few moments, as follows:
Having previously provided yourself with a bit of straight wire or a
small steel rod, turned to run perfectly true in your lathe, and having
fastened this in your chuck in the lathe, loosen the nuts _C C_, so as
to give freedom of movement to the plate _A_; then bring the attachment
to proper position on the lathe bed and fasten it there, after which
move the sliding jaws inward until they bind tightly on the piece of
straight wire held in the chuck and in this position again tighten the
nuts _C_ _C_. Once adjusted to accurate center in this way, no further
adjustment, whatever the size of the work to be operated upon, is
required, until you make another change of jaws.
In use, the end of the work to be operated upon is placed in an
accurate split chuck in the lathe, and the chuck tightened on it, just
sufficiently to hold it in place and to rotate it, the other end being
supported in the central bearing, formed by the sliding jaws. In this
position the jaws may be opened or closed as often as desired, and each
time they will bring the work to accurate center.
A similar attachment to the one above described is extensively used
by machinists and is known as the back rest. In principle it is very
similar, but is more simple in construction, and ambitious workmen can
make them without difficulty. This attachment, which is shown in Fig.
116, differs in its mode of fastening to the lathe bed and the jaws
cannot be opened and closed at one time as in the Potter attachment.
[Illustration: _Fig. 116._]
The illustration shows the rest in position on the lathe bed, looking
from the right-hand end of bed; _m_ shows the base, looking from
above, in direction of arrow _k_; _d_ shows bolt for binding it to the
lathe bed. It does not seem as though it needed much explanation, as
it will be readily seen that the head _d_ of bolt, passes up through
the longitudinal slot in the lathe bed, through the round hole in
base of back rest and is slipped back into slot _m_, when about half
a turn of nut _g_ binds it firmly to the bed. The washer _h_, on the
end of the binding screw, is riveted or soldered in place and should
be close enough to nut _g_ to allow only about half a turn to loosen
the bolt, as that is sufficient, and more space would occasion a loss
of time in running the nut back and forth to bind or loosen the rest.
It will be seen that when the nut _g_ is slackened, it binds against
the washer _h_, and it will stay there, and be just where you want it
when you are ready to use it again. The jaws are of hard brass; about
three sets, with points of different widths, will cover a large range
of work. Those shown in Fig. 116 are suitable for such work as pivoting
small French clock pinions, etc. It will be observed that the jaws are
so made that they may be changed by slightly loosening the screws. The
screw heads should have thin steel washers under them.
[Illustration: _Fig. 117._]
[Illustration: _Fig. 118._]
=296.= =Universal Head.= The universal head has entirely superseded the
clumsy universal mandrel in this country. The example shown in Fig. 117
is more accurate, less clumsy and complicated and will perform all the
work that can be performed on the universal mandrel. The face-plate
is 3½ inches in diameter, but by the use of the two crescent-shaped
slots it will hold anything in size and shape of watch work. The pump
center is operated from the back by the rubber knob and can be used
either with or without a spring. The jaws, which will pass the center,
are held in position on face of plate by springs and are fastened from
the back. Peep holes are provided in these heads in order that the
workman may examine the back of the work at all times. In the Moseley
head, shown in Fig. 117, these holes are of taper form. Fig. 118
shows a universal face-plate to be used in a chuck in the lathe. It is
smaller and less expensive than the universal head and answers very
well for some work, especially that of the lighter kind, but cannot be
recommended as highly as the universal head, as it is not so accurate.
The pump center is used to center, from the back, any object confined
in the jaws, but it sometimes becomes necessary to mount the object,
by means of wax, upon a plate, and hold the plate in the jaws. In such
a case the work must necessarily be centered from the front. This can
be done accurately by means of a piece of pegwood, as ordinarily done
on the lathe, by placing the point in the center hole and the pegwood
resting on the T-rest and observing if the free end of the pegwood
remains stationary.
=297.= =Traverse Spindle Grinder.= This tool will be found very
useful for grinding cutters, lathe centers, pump centers, reamers,
countersinks, squaring up barrel arbors after hardening, or work on any
hardened steel tool. In the hands of an ingenious workman, it will be
found exceedingly useful, as by its aid a great variety of work can be
performed that cannot be accomplished without it. Fig. 119 is intended
to be attached to the slide rest.
[Illustration: _Fig. 119._]
[Illustration: _Fig. 120._]
=298.= =Milling Fixture.= This attachment, which is shown in Fig. 120
is designed to be fitted to the slide rest and holds the wire chuck
vertically under the center of the lathe, so that articles held in the
chucks can be fed under mills or saws held in the saw arbor in the
lathe-head.
[Illustration: _Fig. 121._]
=299.= =Wheel Cutters.= The wheel cutter is a valuable addition to the
lathe. Several different styles of these attachments are made, each
possessing points of merit. They are designed for cutting all kinds of
wheels and pinions used in key and stem-wind watches. When the cutter
spindle is vertical the belt runs directly to it from the countershaft,
but when horizontal, the belt passes over idler pulleys held above the
lathe. One style of wheel-cutting attachment is shown in Fig. 121,
while another style is shown in Fig. 71.
[Illustration: _Fig. 122._]
=300.= =Rounding-up Attachment.= The Webster rounding up attachment,
shown in Fig. 122, is a very useful adjunct to the lathe. It is
attached to the top of the slide-rest. To operate, a pointed taper
chuck is put in the lathe spindle. The wheel to be rounded up is put
into the fixture and the wheel adjusted vertically so that the point of
the lathe center will be at the center of the thickness of the wheel,
after which the lower spindle of the fixture should not be moved. Now
remove the wheel, also the taper chuck, and put the saw arbor, with the
rounding-up center, in the lathe spindle, and adjust the longitudinal
slide of the slide-rest so that the rounding-up cutter will be back of
and in line with the center of the rounding-up fixture, after which the
longitudinal slide of the slide-rest should not be moved. Now put the
wheel and supporting collet in place, and proceed with the rounding-up.
MISCELLANEOUS SMALL TOOLS.
[Illustration: _Fig. 123._]
=301.= =Screw Head Sink Cutter.= This is usually made in the form of
an arbor terminating in a cutting edge similar to the rose-cutter,
but having a projecting pin from its center. This tool will be found
especially useful in replacing broken end-stones. The jewel being set
in brass, is held by two screws, on opposite sides, the screw heads
being let in or sunk even with the surface, half of the screw head
projecting over on the end-stone. The end-stones furnished by the watch
companies are not sunk for these screw heads, but are round and of the
proper diameter. These cutters will cut away from the jewel setting the
space to be occupied by the screw head in a very few moments and in a
very perfect manner. All of the watch companies do not use the same
diameter of screw head in the cock and potance, consequently you will
be compelled to make separate tools for the different makes of watches.
With a set of five or six of these cutters you can fit any American
watch. After you have completed your set, of say five or six cutters,
select a small brass plate and bore five or six small holes in a row,
in which the guide pins of the cutters will enter, and then cut with
the tools a number of sinks, numbering these holes in the plate and
also the arbors of the tools with corresponding numbers. You will then
have a plate similar to Fig. 123 which can then be used as a gauge for
measuring the heads of screws.
[Illustration: _Fig. 124._]
These cutters are easily made as follows: cut off a piece of wire of
the required diameter, about one inch long, and place it in a chuck
that fits it snugly and turn one end to a center, about 40°; now
reverse the wire in the chuck and be sure it is true; select a drill
that will pass through the screw hole in the cock or potance freely
and proceed to drill a hole in the center of the end of the wire, about
¹⁄₁₆ of an inch deep. Remove from the lathe and with a sharp file and
graver, proceed to cut a series of teeth as equal and even as possible.
Use a good strong glass while working and be sure you have every tooth
sharp and perfect, as upon this depends the quick and nice work you
expect from the tool. When this is well done, proceed to temper fairly
hard and polish up the outside to make it look workmanlike. Now select
a piece of steel pivot wire, of a size that will almost fit in the hole
drilled in the end of the tool and polish down to the proper size to
drive in the hole tightly. Allow the wire to project about ¹⁄₁₆ of an
inch, taper the point and polish. The tool is now complete and will
resemble Fig. 124. Select an end-stone of a diameter to fit tightly in
the cock or potance, as maybe required; set the hole jewel in place and
then the end-stone pressed down tightly against the hole jewel. Place
your cutter in a chuck that fits it true; select a smaller medium sized
drill rest and place it in the tail stock spindle. Hold the cock, or
potance, with the jewels in place, against the drill rest, level, and
proceeding to run the lathe at a fair speed, slowly feed the cock or
potance to the cutter, the projecting pivot in the end of the cutter
passing through the screw hole and acting as a guide to keep the cutter
in the center of the hole. Caution must be exercised, or you will cut
the recess for the screw heads too deep, as these little cutters are
very deceiving and cut much faster than you would suppose. In fitting
an end-stone, select one that is more than flush when the jewel hole
and end-stone are in the proper position, and after sinking the screw
head as described, turn off on the lathe almost flush or level. Make a
small dot on one side of the end-stone as a mark or guide in replacing
it. Remove the end-stone and proceed to polish the top of the setting
on a plate glass polisher.
=302.= =Screw Extractors.= The Bullock Screw Extractor, shown in Fig.
125, is a simple yet very valuable tool to the watchmaker who finds he
has a plate in which a screw has been broken off. To use this tool,
first fasten it in your vise, then bring one end of the broken or
rusted-in screw against screw center and the broken screw head against
screw driver; turn the washers so as to hold the broken screw firmly in
place; turn the plate gently and the broken screw will follow the screw
driver point out of the plate. It may be necessary in some instances to
turn the screw driver point against the broken head with a good deal of
force in order to start the screw. A little benzine or kerosene applied
to the screw will help to loosen it.
[Illustration: _Fig. 125._]
The ingenious workman can, with the expenditure of a little time, make
an attachment for removing broken screws, somewhat similar to the
above. Take two common steel watch keys having hardened and tempered
pipes—size, four or five—having care that the squares in each are of
the same size and of good depth. Cut off the pipes about half an inch
from the end; file up one of these for about one-half its length, on
three equal sides, to fit one of the large split chucks of the lathe.
Drill a hole in one of the brass centers of the lathe of sufficient
size and depth, into which insert the other key-pipe, and fasten with
a little solder. Soften a piece of Stubbs’ wire, to work easily in the
lathe, and turn down for an eighth of an inch from the end to a size
a little smaller than the broken screw in the plate; finish with a
conical shoulder, for greater strength, and cross-file the end with a
fine slot or knife-edge file, that the tool may not slip on the end of
the broken screw; cut off the wire a half inch from the end and file
down to a square that will fit closely in one of the key-pipes. Make
a second point like the first one and fit it to the other key-pipe;
harden in oil, polish, and temper to a dark straw color. Fit the brass
center into the tail stock. To use, put the tools in place in the
lathe, place the broken end of the screw against the end of the point
in the lathe-head; slide up the back center and fasten the point firmly
against the other end of the screw, that it may not slip or turn;
revolve the plate slowly, and the broken screw, being held fast between
the two points will be quickly removed. To remove a broken pillar
screw, place the broken screw against the point in the lathe-head,
holding the plate firmly with the right-hand, the pillar on a line
with the lathe center; turn the lathe-head slowly backward with the
left-hand, and the screw will be removed. Should the tool slip on the
broken screw, and fail to draw it out, drill a hole in the lower or
dial side of pillar, down to the screw point (if the size of the pillar
will admit of it), and with the second point in the back center, remove
the screw in the same manner as in the first process. Five or six sizes
of these points will be found sufficient for the majority of these
breakages that may occur.
It sometimes happens that a screw gets broken off in a watch plate in
such a manner that it is impossible to remove it with tools without
marring the plate. In such an event proceed as follows: Put enough
rain water in a glass tumbler to thoroughly cover the plate and add
sulphuric acid, until the water tastes a little sharp. Place the plate
in the solution and allow it to remain a few hours, when the screw
will partially dissolve and drop out. Remove from the solution, wash
thoroughly in clean water, then in alcohol and dry in saw dust. The
solution will not injure the brass plate or gilding in the slightest,
but care must be taken to remove all other screws or cemented jewels,
previous to immersion.
[Illustration: _Fig. 126._]
=303.= =Roller Remover.= There are numerous designs in the way of
roller removers upon the market, some of them good but many of them
weak and liable to bend where the roller is very tight on the staff.
All points being considered, the Hardinge remover, shown in Fig. 126,
is perhaps the strongest and best on the market and is built on true
mechanical principles.
The nose in the center and top of the illustration is drilled up so as
to receive a balance pivot without bearing on its point, and can be
moved towards or from the two bent prongs by means of the thumb nut
at the bottom of the tool. The prongs can be spread apart or drawn
together, and are secured in place by means of the binding screws at
the sides. In using the remover the feet of the two prongs are brought
under the roller and secured by the binding screws. The nose is now
advanced against the shoulder of the bottom pivot and the staff can be
driven out without damage to either roller or staff.
[Illustration: _Fig. 127._]
=304.= =Balance Protectors.= These are of two kinds and for entirely
different operations. The Arrick protector, shown in Fig. 127, is used
for protecting balances while working upon the pivots while in the
lathe. No matter how careful a person may be, accidents will happen,
and the least accident to a compensation balance gives the workman
considerable trouble. The least slip of the graver, polisher or hand
rest and great damage is the result. The staff is passed through the
hole in the protector, and held in a wire chuck, and the protector
is secured to the arms of the balance by two screws. The Bullock
protector, shown in Fig. 128, is designed to protect the balance and
other wheels from heat while drawing the temper from staff or pinion
for the purpose of pivoting.
[Illustration: _Fig. 128._]
[Illustration: _Fig. 129._]
=305.= =Beat Block.= This simple device obviates the necessity of
marking the balance to see that it is in beat. Before taking off the
hair spring lay it on the block, shown in Fig. 129, turn the balance so
the roller pin hits on the side the arrow points, then turn the table
so that the line comes under the stud. In replacing the balance put the
stud over the line and it will then beat the same as before. By using
this tool you also avoid getting the balance out of true.
=306.= =Female Centers.= Centers are of two kinds,, male and female.
The ordinary centers that accompany the lathe, which are male centers,
are familiar to all watchmakers. Female centers, however, are not so
well known among watchmakers, and they can be used to great advantage
in many operations where other and less simple attachments and means
are usually resorted to. You should have at least six pairs of female
centers, the largest being one-fourth of an inch in diameter, which
will accommodate as large a piece as you will wish to handle on your
watch lathe, viz: winding arbors for clocks. These female centers are
made from steel tapers, the same as male centers are made, but instead
of turning the end to a sharp point they are countersunk, Fig. 130.
First place the taper in a chuck and turn off the outside and end true;
drill a small hole in the center of the taper, while the lathe is
running, and deep enough so the countersink will not reach the bottom
of the hole, or one-eighth of an inch deeper than the countersink.
Harden the end only, and after tempering polish off the bluing. After
you have made all the sizes you require, test all of them in your lathe
to make sure they did not get out of true in tempering.
[Illustration: _Fig. 130._]
These female centers are very useful for holding or suspending any
article in the lathe that is too large to be held in the split chucks.
Pivots of clocks can be turned and polished very quickly and accurately
in these centers.
Almost any kind of large work can be done on a medium sized
watchmaker’s lathe by fitting to it a face plate one and three-fourths
inches in diameter, with four slots, and fitted to a chuck with
a standard taper hole to receive both male and female centers
interchangeably. With two styles of dogs, almost any kind of large
clock work can be readily handled.
These centers prove very useful for many odd jobs. As an example: It is
a very common occurrence to hear an American clock beat irregularly,
caused by the escape wheel being out of round. Select a pair of female
centers that will admit the ends of the pivots of the escape wheel
snugly; place one center in the taper chuck and the other in the tail
stock spindle, and suspend the escape pinion in these centers; fasten
on a dog, run the lathe at a high speed and hold a fine sharp file so
it will touch the teeth of the ’scape wheel slightly, and in a moment
the wheel will be perfectly round, after which sharpen up the teeth
that are too thick.
[Illustration: _Fig. 131._]
=307.= =Drill Rest.= In using the lathe for drilling, a great saving
in both time and drills can be effected by using a drill rest similar
to that shown in Fig. 131. It is well to have a half dozen different
sizes, starting at ¼ inch and increasing by ⅛ inch, for various classes
of work. These rests are not kept by material dealers, but can be
made by the watchmaker. Saw from a piece of rolled sheet brass, say
1-16 inch thick, the circles required, leaving metal enough to finish
nicely. Place a steel taper plug in the taper chuck of your lathe and
turn down a recess, leaving a shoulder on the taper. Drill a hole
through the brass plate to fit the steel taper tightly. Place the end
of the taper on a lead block and proceed to rivet the brass plate,
on the taper, making sure that it is true replace the taper in the
lathe chuck and proceed to turn the face and edge of the brass plate
perfectly true and to the proper size. Those who have tried to drill
a straight hole through an object by holding it in the fingers know
just how difficult it is to do, but by placing one of these drill rests
in the spindle of the tail stock, placing the article to be drilled
against it and bringing it up against the drill, you can drill the hole
perfectly upright and avoid all danger of breaking the drill.
[Illustration: _Fig. 132._]
=308.= =Filing Fixture or Rest.= These rests will be found very
convenient in squaring winding arbors, center squares, etc. There are
several makes of these tools, but they are all built upon the same
principle, that of two hardened steel rollers on which the file rests,
and Fig. 132 is a fair example. One pattern is made to fit in the hand
rest after the =T= is removed, while the other is attached to the bed
of the lathe in the same manner as the slide rest. The piece to be
squared is held in the split or spring chuck in the lathe, and the
index on the pulley is used to divide the square correctly. Any article
can be filed to a perfect square, hexagon or octagon as may be desired.
The arm carrying the rollers can be raised or lowered as required for
adjustment to work of various sizes.
=309.= =Filing Block.= A contrivance made to take the place of the
filing rest, which was made of box wood or bone. Ide’s filing fixture,
shown in Fig. 133, consists of a cylinder of hardened steel, riveted
upon a staff which in turn enters a split socket. The surface of
the steel cylinder is grooved with various sizes of grooves for the
different sizes of wire, or to suit any work.
[Illustration: _Fig. 133._]
[Illustration: _Fig. 134._]
Fig. 134 illustrates Melotte’s revolving bench block, which combines
both anvil and filing block. No. 1 is a steel anvil which may be
instantly revolved and stopped on quarters. No. 2 is a rubber block,
held by friction on its arm, and can readily be turned to any position.
This rubber, being slightly elastic, makes a very suitable filing bed
for small articles of any material and may be used without risk of
scratching or defacing polished surfaces. No. 3 is a wooden block, held
on to its arm by a spring friction device, which also allows it to be
turned around to any desired position. The three-armed hub is revolved
by pulling out slightly and is automatically held perfectly firm and
solid in any of the three positions.
[Illustration: _Fig. 135._]
=310.= =Micrometer Caliper.= Fig. 135 is a full size cut of the Brown &
Sharp Mfg. Co.’s micrometer caliper. It measures from one-thousandth of
an inch to one-half inch. It is graduated to read to thousandths of an
inch, but one-half and one-quarter thousandths are readily estimated.
This instrument is also graduated to the hundredths of a millimeter,
but when so graduated the table of decimal equivalents is omitted.
They are also made to read to ten thousandths of an inch. The edges of
the measuring surfaces are not beveled, but are left square, as it is
more convenient for measuring certain classes of work. It will gauge
under a shoulder or measure a small projection on a plain surface.
Watchmakers will especially appreciate micrometers of this form. This
tool will be found very useful for gauging mainsprings, pinions, etc.
In the caliper, shown by cut, the gauge or measuring screw is cut on
the concealed part of the spindle C, and moves in the thread tapped in
the hub A; the hollow sleeve, or thimble D is attached to the spindle
C and covers and protects the gauge screw. By turning the thimble, the
screw is drawn back and the caliper opened.
The pitch of the screw is 40 to the inch. The graduation of the
hub A, in a line parallel to the axis of the screw, is 40 to the
inch, and is figured 0, 1, 2, etc., every fourth division. As the
graduation conforms to the pitch of the screw, each division equals the
longitudinal distance traversed by the screw in one complete rotation,
and shows that the caliper has been opened 1-40th or .025 of an inch.
The beveled edge of the thimble D is graduated into 25 equal parts,
and figured every fifth division 0, 5, 10, 15, 20. Each division when
passing the line of graduation on hub A, indicates that the screw has
made 1-25th of a turn, and the opening of the caliper increased 1-25th
of 1-40th, or a thousandth of an inch.
Hence, to read the caliper, multiply the number of divisions visible
on the scale of the hub by 25, and add the number of divisions on the
scale of the thimble, from zero to the line coincident with the line
of graduation on hub. For example: As the caliper is set in the cut,
there are three whole divisions visible on the hub. Multiply this
number by 25, and add the number of divisions registered on the scale
of the thimble, which is 0 in this case, the result is seventy-five
thousandths of an inch. (3 × 25 = 75 0 = 75). These calculations are
readily made mentally.
Differences between Wire Gauges in Decimal Parts of an Inch.
Key:
A - No. of Wire Gauge.
B - American or Brown & Sharpe.
C - Birmingham or Stubs’.
D - Washburn & Moen Manufacturing Co., Worcester, Mass.
E - Trenton Iron Co., Trenton, N.J.
F - New British.
G - Old English from Brass Mfrs. List.
H - No. of Wire.
==================================================================
A | B | C | D | E | F | G | H
-------+---------+------+-------+--------+-------+--------+-------
000000 | ---- | ---- | .46 | ---- | ---- | ---- | 000000
00000 | ---- | ---- | .43 | .45 | ---- | ---- | 00000
0000 | .46 | .454 | .393 | .4 | .4 | ---- | 0000
000 | .40964 | .425 | .362 | .36 | .372 | ---- | 000
00 | .3648 | .38 | .331 | .33 | .348 | ---- | 00
0 | .32495 | .34 | .307 | .305 | .324 | ---- | 0
1 | .2893 | .3 | .283 | .285 | .3 | ---- | 1
2 | .25763 | .284 | .263 | .265 | .276 | ---- | 2
3 | .22942 | .259 | .244 | .245 | .252 | ---- | 3
4 | .20431 | .238 | .225 | .225 | .232 | ---- | 4
5 | .18194 | .22 | .207 | .205 | .212 | ---- | 5
6 | .16202 | .203 | .192 | .19 | .192 | ---- | 6
7 | .14428 | .18 | .177 | .175 | .176 | ---- | 7
8 | .12849 | .165 | .162 | .16 | .16 | ---- | 8
9 | .11443 | .148 | .148 | .145 | .144 | ---- | 9
10 | .10189 | .134 | .135 | .13 | .128 | ---- | 10
11 | .090742 | .12 | .12 | .1175 | .116 | ---- | 11
12 | .080808 | .109 | .105 | .105 | .104 | ---- | 12
13 | .071961 | .095 | .092 | .0925 | .092 | ---- | 13
14 | .064084 | .083 | .08 | .08 | .08 | .083 | 14
15 | .057068 | .072 | .072 | .07 | .072 | .072 | 15
16 | .05082 | .065 | .063 | .061 | .064 | .065 | 16
17 | .045257 | .058 | .054 | .0525 | .056 | .058 | 17
18 | .040803 | .049 | .047 | .045 | .048 | .049 | 18
19 | .03539 | .042 | .041 | .039 | .04 | .04 | 19
20 | .031961 | .035 | .035 | .034 | .036 | .035 | 20
21 | .028462 | .032 | .032 | .03 | .032 | .0315 | 21
22 | .025347 | .028 | .028 | .27 | .028 | .0295 | 22
23 | .022571 | .025 | .025 | .024 | .024 | .027 | 23
24 | .0201 | .022 | .023 | .0215 | .022 | .025 | 24
25 | .0179 | .02 | .02 | .019 | .02 | .023 | 25
26 | .01594 | .018 | .018 | .018 | .018 | .0205 | 26
27 | .014195 | .016 | .017 | .017 | .0164 | .01875 | 27
28 | .012641 | .014 | .016 | .016 | .0148 | .0165 | 28
29 | .011257 | .013 | .015 | .015 | .0136 | .0155 | 29
30 | .010025 | .012 | .014 | .014 | .0124 | .01375 | 30
31 | .008928 | .01 | .0135 | .013 | .0116 | .01225 | 31
32 | .00795 | .009 | .013 | .012 | .0108 | .01125 | 32
33 | .00708 | .008 | .011 | .011 | .01 | .01025 | 33
34 | .006304 | .007 | .01 | .01 | .0092 | .0095 | 34
35 | .005614 | .005 | .0095 | .009 | .0084 | .009 | 35
36 | .005 | .004 | .009 | .008 | .0076 | .0075 | 36
37 | .004453 | ---- | .0085 | .00725 | .0068 | .0065 | 37
38 | .003965 | ---- | .008 | .0065 | .006 | .00575 | 38
39 | .003531 | ---- | .0075 | .00575 | .0052 | .005 | 39
40 | .003144 | ---- | .007 | .005 | .0048 | .0045 | 40
-------+---------+------+-------+--------+-------+--------+-------
[Illustration: _Fig. 136._]
=311.= =Registering Gauge.= The registering gauges shown in the
illustrations are two of the best examples of this class of tools. They
are manufactured by A. J. Logan, Waltham, Mass., and are very accurate
and nicely finished. Fig. 136 is an upright and jaw gauge, and Fig.
137 is designed as a jaw and depth gauge. They are both made to gauge
one-thousandth of a centimeter or one-thousandth of an inch. Fig. 137
shows the piece of work marked A being gauged, while B represents a
sliding spindle to get the depth of a hole or recess, or the thickness
of any piece of work, which will be indicated on the dial.
[Illustration: _Fig. 137._]
[Illustration: _Fig. 138._]
[Illustration: _Fig. 139._]
Another form of registering gauge is shown in Fig. 138. It is an
English gauge and but little used in this country. The principle of its
construction, however, is good, and any ingenious watchmaker can make
it. The back of the dial is recessed and arranged as in Fig. 139. One
limb is fixed; the other is pivoted, and has a few rack teeth meshing
into a center pinion. The pinion carries the hand, which should make a
revolution in closing the calipers. The spiral spring attached to the
pinion is to keep it and the hand banked in one direction for shake.
The spring _s_ is to keep the jaws open. The milled headed screw and
the clamp _c_ are to fix the jaws in case it is required to do so.
A cover is snapped into the recess, and takes the back pivot of the
pinion.
[Illustration: _Fig. 140._]
=312.= =Staff Gauge.= The tool shown in Fig. 140 is designed for
measuring the height of the balance staff from the balance seat to
the end of the top pivot. The illustration is enlarged to give more
distinctness. _E E′_ is a piece of curved steel about ¹⁄₂₀ of an inch
thick, and ¹⁄₂₅ of an inch wide. On the lower side from _E′_ to the
end, the arm is filed down in width and thickness to correspond to an
ordinary balance arm; _C_ is a slot in the upper arm _E_, which allows
_A_, _B_, _D_, _A′_ to be moved backward and forward. _D D′_ is a round
brass post drilled and tapped. The part _D′_ has a thread cut on it,
and the part shown in the slot _C_ fits with easy friction. _B_ is a
lock-nut, drilled and tapped to fit the thread on _D′_. It is for the
purpose of clamping _D D′_ against the arm _E_. _A A′_ is a small steel
screw with milled head, and is made to fit the tapped hole in _D D′_.
Mr. Beeton describes his method of using this tool as follows: Take
your measurement of the distance _the balance seat is to be from
the end of the top pivot_, as follows: remove the end-stone in
balance-cock, and screw the cock on the top of the top plate (18-size
full plate movement); then taking the plate in your left-hand, and
tool (shown in Fig. 139) in your right, place _H_ in position, so that
the end of the screw _A′_ rests on the jewel in the balance cock, and
notice the position of the arm _E′_ which corresponds to the balance
arm, between the top plate and under side of the balance-cock. If the
distance between the arm _E′_ and end of screw _A′_ is too great,
the arm _E′_ will be too low and touch the plate; if not enough, it
will be too high and touch the regulator pins. Therefore, all that is
necessary to do is to move the screw _A A′_ up or down as the case may
be, sufficiently to ensure that the arm _E′_ will assume the position
the _arm of the balance_ is to have. Take an 18-size balance with
oversprung hairspring, the arm is at the bottom of the rim; in that
case, when measuring, the screw _A′_ is adjusted so as to bring the
arm _E′_ close to the plate, when _A′_ is resting on the balance jewel;
if the balance is old style with undersprung hairspring, the balance
arm is at top of rim, in which case _A′_ is adjusted so that the arm
_E′_ is close to the balance cock; if the balance arm is in the center
of the rim, as in some English and Swiss balances, the screw _A′_ is
adjusted so that the arm _E′_ is midway between the plate and cock.
The reason the part _A_, _B_, _D_, _A′_ are arranged to move laterally
in slot _C_ is, because all balance shoulders are not the same distance
from the center, and where, in some cases, the screw _A′_ would be in a
line with the center of the staff when the arm _E′_ was resting on the
balance seat, in other cases it would reach past the center, of course,
short of it; and, therefore, it is made adjustable to suit all cases.
[Illustration: _Fig. 141._]
=313.= =Staff or Cylinder Height Gauge.= The obvious advantage of this
tool, which is shown at Fig. 141, is the automatic transfer of the
measurement so that it may be readily applied to the work in hand. The
tool, as the illustration shows, consists of a brass tube terminating
in a cone-shaped piece. To the bottom of this cone is attached a disc
through which a needle plays. Around the upper end of the tube is a
collar upon which is fixed a curved steel index finger. A similar jaw,
which is free to move, works in a slot in the tube. The movable jaw
is tapped and is propelled by a screw that terminates in the needle
point. This tool is very useful in making the necessary measurements
required in putting in a staff. To use it in this work, set the pivots
of the gauge through the foot hole, and upon the end-stone project the
needle such a distance as you wish the shoulder to be formed above the
point of the pivot. Next set the gauge in the foot hole as before, and
elevate the disc to a height that shall be right for the roller, which
is done by having the lever in place, the little disc showing exactly
where the roller should come. Finish the staff up to that point; then
take the next measurement from the end-stone to where the shoulder
should be, for the balance to rest upon. This point being marked,
the staff can be reversed and measurements commenced from the upper
end-stone, by which to finish the upper end of the staff. Distances
between the shoulders for pinions and arbors can be obtained with the
same facility, a little practice being the only requisite.
=314.= =Vernier Caliper.= Fig. 142 is an illustration of the Vernier
Caliper, a light, convenient and valuable instrument for obtaining
correct measurements. The side represented in the illustration is
graduated upon the bar to inches and fiftieths of an inch, and by the
aid of a Vernier is read to the thousandths of an inch (see description
below). The opposite side is graduated to inches and sixty-fourths of
an inch. The outside of the jaws are of suitable form for taking inside
measurements, and when the jaws are closed, measure two hundred and
fifty thousandths of an inch in diameter.
[Illustration: _Fig. 142._]
These instruments can be furnished with millimeters (in the place of
sixty-fourths of an inch), and provided with a Vernier to read to
one-fiftieth of a millimeter.
On the bar of the instrument is a line of inches numbered 1, 2, 3,
each inch being divided into tenths, and each tenth into five parts,
making fifty divisions to one inch. Upon the sliding jaw is a line
of divisions (called a Vernier, from the inventor’s name), of twenty
parts, figured 0, 5, 10, 15, 20. These twenty divisions on the Vernier
correspond to extreme length with nineteen parts, or nineteen-fiftieths
on the bar, consequently each division on the Vernier is smaller than
each division on the bar by one-thousandth of an inch. If the sliding
jaw of the caliper is pushed up to the other, so that the line 0 on
the Vernier corresponds with 0 on the bar, then the next two lines on
the left will differ from each other one-thousandth of an inch, and
so the difference will continue to increase one-thousandth of an inch
for each division till they again correspond on the twentieth line on
the Vernier. To read the distance the caliper may be open, commence by
noticing how many inches, tenths and parts of tenths the zero point on
the Vernier has been moved from the zero point on the bar. Then count
upon the Vernier the number of divisions until one is found which
coincides with one on the bar, which will be the number of thousandths
to be added to the distance read off on the bar. The best way of
expressing the value of the divisions on the bar is to call the tenths
one hundred thousandths (.100) and the fifths of tenths, or fiftieths,
twenty thousands (.020). Referring to the accompanying cut, it will
be seen that the jaws are open one-tenth of an inch, which is equal
to one hundred thousandths (.100). Suppose now, the sliding jaw was
moved to the left, so that the first line on the Vernier would coincide
with the next line on the bar, this would then make twenty thousandths
(.020) more to be added to one hundred thousandths (.100), making the
jaws then open one hundred and twenty thousandths (.120) of an inch. If
but half the last described movement was made, the _tenth line on the
Vernier_ would coincide with a line on the bar, and would then read,
one hundred and ten thousandths (.110) of an inch.
[Illustration: _Fig. 143._]
=315.= =Hair Spring Stud Index.= Fig. 143 illustrates Johanson’s hair
spring stud index. The engraving shows the full size of the tool, which
consists of a steel plate mounted on feet, and pierced with a number
of holes for the reception of screws, when taking down a watch. In the
center of the index is a hole for the staff, and an oblong slot for the
reception of the roller jewel. To get any American movement in beat,
proceed as follows: In front of No. 100 is a small spring; push same
towards No. 10; then place the balance on top of the stand, with staff
in center and roller jewel in the oblong hole; let the spring back
gently; the balance will then take its own position. Set degree hand
in front of the desired degree, as per direction on index table; place
hair spring stud in front of degree hand, and push on the collet.
INDEX TABLE FOR HAIR SPRING STUDS.
_Size._ _Degree._
Columbus 18 Open Face Breguet 23
Columbus 6 Open Face Breguet
Elgin 18 Open Face Breguet 66
Elgin 16 Open Face Breguet 52
Elgin 16 Flat Hair Spring 52
Elgin 10 Flat Hair Spring 50
Elgin 6 and 8 Flat Hair Spring 50
Elgin 0 Flat Hair Spring
Illinois 18 Open Face Breguet 33
Illinois 18 Hunting 84
Illinois 18 Open Face Flat 89
Illinois 16
Illinois 6 Hunting 52
Illinois 4
Hampden 18 Dueber Hunting 80
Hampden 18 Open Face 75
Hampden 16
Hampden 6 Hunting 50
Howard 18 Old Model 5
Howard 18 New Model 23
Howard 16
Howard 6
Rockford 18 27
Rockford 6
Waltham 18 Key Flat Hair Spr’g 48
Waltham 18 O. F. Hair Spring 61
Waltham 18 Breguet 50
Waltham 14-16 42
Waltham 4-6 50
Waltham 1 42
Seth Thomas 18 Open Face 50
Seth Thomas 18 Hunting 52
=316.= =Oil-cup Drills or Chamfering Tools.= The reservoirs that
contain a supply of oil at the ends of pivot holes are made in the
lathe with a semi-cylindrical drill, or by hand with a chamfering tool
of the form shown at B or C, Fig. 144. A drill gives a clean cut, but
necessitates a subsequent polishing of the hole; as to the chamfering
tool here referred to, some inconvenience will be experienced in its
use, owing to the point being apt to jump out of the hole and make
irregular scratches on the brass, which are difficult to remove.
[Illustration: _Fig. 144._]
[Illustration: _Fig. 145._]
The best shapes of drills for making, or at any rate for re-forming or
finishing oil-cups, are shown at D and F, Fig. 144, and in Fig. 145.
D and F are two drill-blades that terminate in non-cutting circular
arcs. The flat curved end is more and more inclined from the top
towards the corner, from _i_ towards the side _e_; the angle at _i_
becoming more acute, and at _e_ more obtuse towards the corners. The
drill will, of course, only cut when rotating in one direction; in the
other direction the obtuse angles and the reverse sides of the cutting
angles will act as burnishers. Thus if the angles on either side are
well formed and the blade has been polished, the surface of the oil-cup
will be clean cut and polished. F is similar to D, but made from a
steel rod.
=317.= _Observations on making the oil-cups._ Reservoirs that are made
with a drill, or with a chamfering tool by hand, will often be found
to be eccentric, and, when a pivot-hole is bushed and re-drilled,
it proves to be struck from a different center from the oil-cup. In
such cases watchmakers often give themselves endless trouble without
securing a cup of good form and well centered. This difficulty can be
avoided by using the tool in a lathe driven by a wheel; then, holding
the plate in one hand square against a drill rest in tail stock,
advance the tail stock with the other hand so as to bring the plate in
contact with the drill.
When it is only required to correct the form of an oil-cup, the drill
may be replaced by a rod with file cuts on its rounded extremity (H,
Fig. 144). The reader will find no difficulty in making such a cutter
for himself, drawing a file with both hands over the rounded end, but
always in the direction of the file-cuts. After covering the surface
with lines in this manner, rotate the cutter through a right angle and
form a number of cross cuts. Or roughen the surface with a chisel of
the form shown at H; after making a few cuts parallel to each other,
turn the chisel through an angle and repeat the operation.
=318.= =Chamfering Tool.= As is well known, this is used for removing
the roughness that a drill leaves at the edge of a hole, or to take off
the cutting edge around a screw head sink, etc., thus forming a bevel
edge. The tool commonly has a flat semicircular blade, the diameter of
which depends on size of hole to be made; this semicircle is ground to
a cutting edge like a drill, as shown at A, Fig. 144. Chamfering tools
are also made pyramidal, with flat faces, as at B and C; the angle
at the apex is more or less acute, according to the depth of chamfer
required.
The oil-cup drills D and F are also used for chamfering the edge of a
hole.
A cone formed at the extremity of a piece of pinion wire with a cutting
edge on each leaf and hardened will be found very useful for this
purpose.
=319.= The two forms of chamfering tool first described leave a series
of undulations on the bevel edge, so that, instead of being conical, it
presents a number of small facets. This inconvenience can be avoided by
using the tool shown at Z, Fig. 145.
A small disc of hardened steel is pivoted within a recess formed at
the end of a rod, the pin on which it rotates being at right angles to
the direction of the rod. As is seen in the figure to right of Z, the
section of this roller is a rectangle, and the surface is carefully
polished, the edges being left sharp.
Clockmakers make use of a tool for forming oil-cups that only differs
from the one above described in two particulars: (1) The disc is fixed
on its axis; and (2) the edge, instead of being square to the two
faces, is inclined as shown at _j_ and at the same time is slightly
rounded crosswise.
A few trials will be found necessary before the most convenient
thickness and inclination of edge are arrived at.
=320.= =Hollow Chamfering Tools.= These, as is well known, are used for
removing the angles at the ends of cylindrical rods, of steady-pins,
etc., or for rounding them off. Three forms are shown at O, Q, N, Fig.
146.
[Illustration: _Fig. 146._]
O is a round rod, the flat end of which has been filed across with
the corner of a triangular file. Four cutting edges are thus produced
which will act on the end of any object that rotates within them, or
_vice versa_. If it be required to form a very acute angle, two slits
must be cut with a screw-head file and the sides afterwards inclined
to the required extent with a flat file. This tool will serve a double
purpose: (1) to chamfer off the edge of a rod; and, (2) by prolonging
this operation to form a point at the end.
As a rule, when it is desired to round off, say, a pillar of a clock
after reducing its length or from any other cause, a hollow chamfering
tool of very open angle is used, a rocking motion being imparted to
it round the axis of the spindle; it is better to use a tool of the
shape shown at N or Q. The latter, Q, is easily formed by strokes of
a rat-tail file at right angles across its end; the other, N, is cut
internally with a shaped chisel or with a small rotating cutter to
which different inclinations are given during the cutting, as is also
done when using the chisel.
=321.= The tool shown at O, Fig. 146, has been modified as follows
by M. Roze. The two notches at right angles are replaced by three
equidistant notches of equal depth. To make these in a piece of round
steel it should be divided on the circumference into six equal parts;
then cut the three notches as follows: Calling the points marked on
the circumference 1, 2, 3, 4, 5, 6, one notch will lie parallel to the
line joining 1, 3, and equidistant between this line and the point 5; a
second will be parallel to 3, 5, and midway between that line and point
1, and the third will be parallel to 5, 1, and midway between this and
the point 3.
In a hollow chamfering tool thus constructed it will be found that only
the three long sides 1, 3, 5, actually cut, and at 2, 4 and 6 are short
sides that are set back. But when a file is laid on the face joining
two of the former sides, say 1, 3, the short faces 4, 6, will protect
the cutting edge 5 from contact with the file.
=322.= =Tool for Centering Rods.= These appliances are well known to
watchmakers, who often employ them for marking the position of the hole
in the brass wire when making bushings. It is advisable to have such a
tool somewhat large, about a third as large again as that shown at _s
r_, Fig. 147.
[Illustration: _Fig. 147._]
The head of the centering punch or drill is filed flat on either
side, and this flattened portion passes into a notch in the spring
_r_, which maintains it in position and prevents rotation when the
triangular-pointed blade is pressed against the end of this rod, this
rod being caused to rotate in the hollow cone of _s_. Instead of a
spring such as _r_, a helical spring is often used; but it then
becomes necessary to fix a pin in the drill that slides in a groove in
_s_, so as to prevent the drill from rotating.
=323.= =Centering with a Set-Square.= The set square may be used for
centering round rods, and the following is a very simple mode of
applying it:
[Illustration: _Fig. 148._]
On one arm of the square R, Fig. 148, a triangular plate _c d_ is
screwed or riveted so that its edge _c d_ exactly bisects the right
angle, that is, divides it into two equal angles. The flat end of a
round rod is held within the angle and against the plate, a line being
traced on it along _c d_; it is then turned through about a right angle
and a second line traced. The intersection of these two lines gives the
axis of the rod.
=324.= =Tool for Roughing Out Points.= This is merely the inverted
chamfering tool of which two forms are described in paragraphs
=320-21=, one of them being also shown at O, Fig. 146. It will be
evident that when the end of a rod is caused to rotate in this hollow
cone it will take its form.
In some cases it may be found convenient to place such a tool in the
tail stock of the lathe.
If the bottom of the cone at the end of O were prolonged by continuing
the cuts farther down with a thin flat file, the point of the rod might
be formed like a conical-headed screw before it is tapped.
=325.= =Balance-spring Collet Tool.= This convenient little tool for
rotating the balance-spring collet is commended almost as much by its
simplicity and facility of construction as by its usefulness.
[Illustration: _Fig. 149._]
A steel rod _n_, Fig. 149, is fixed in a handle T; it terminates in a
cone _a_ and is drilled with a fine hole as indicated by the dotted
lines. A thin wing _b_, pointed at its extremity, is also attached to
the handle.
Holding the balance between the fingers of the left hand and the
tool in the right, the blade _b_ is introduced into the slit in the
collet while _a_ rests on the balance staff shoulder, the pivot being
within the hole _n_. Now rotate to the right or left until the stud is
opposite to the mark on the balance rim, and this may be done without
danger, providing the tool is held firmly and vertical.
[Illustration: _Fig. 150._]
=326.= =Watch-hand Holder.= A very convenient form of tool, in which
to clamp a hand while enlarging the center hole is represented in
Fig. 150. Two brass plates, _f_ and _g_, are hinged at _m_ like a
sector. A collar, _a b_, surrounding the two is pivoted at _a_ and has
a clamping-screw _b_ by which the two plates can be forced together.
Several circular sinks of different sizes and equally divided between
the two plates, are cut of a depth varying from one-half to two-thirds
that of the plates, and they must be made to increase in diameter as
they get deeper, thus resembling the internal groove that receives a
barrel cover. The plate _a_ is cut away along the portion _c d_ and
grooves are formed to leave passages open between this surface and the
bottom of the sinks in _g_ and _f_.
When it is required to enlarge the hole of a watch-hand, place it,
inverted, in the hole of suitable size, as shown at _c_ of the figure,
and tighten the screw _b_. Held round the whole or greater part of
its circumference, the hand is thus firm and its center hole can be
enlarged without risk, either with a drill or broach; the hand will not
show marks due to the pressure with which it has been held.
=327.= =Common Hand fitting Pliers.= The sliding tongs with large flat
head, perforated with a number of holes in which the head of a hand is
clamped when the opening requires to be enlarged, are often useful,
but we feel them to be less so than the holder just described. It is
desirable that the inner faces of their jaws, which are usually left
rough, be at least smoothed.
[Illustration: _Fig. 151._]
=328.= =Another form of Watch-hand Holder.= M. Fiquemont has devised
the simple little tool shown in Fig. 151. It consists of a short brass
rod R, perforated lengthwise and having a thread cut externally on the
surface _a b_. It should be reduced in thickness below this tapped
portion. The rod, shown also in longitudinal section at P, is cut into
four quarters by two slits from _a_ to _b_, which are at right angles
and leave the points as indicated apart at _d_. The elasticity of these
four quarters should make them take the form of a reversed cone when
holding a hand, so that the ascent of the screw _c_ shall tighten them.
Within the head _a_ of the tool is formed a circular recess, so that,
if the reversed head of a watch-hand be placed within it and the screw
made to ascend, it will be held very firmly by the circumference, as
seen in the figure. The hand will thus be perfectly free to adjust in
any way that is needed for fitting it while held at the end of the
tool, and without being removed before the work is complete. Three or
four sizes will suffice for all ordinary watch-hands.
A tool may be made in a similar manner, except that the screw is not
divided by the longitudinal slits, and the hand is held against the
point by a lantern (similar to those of a screw-point tool), which
must be cut away in the manner indicated in Fig. 150, explained above
(=326=). An assortment of three or four lanterns will render the tool
serviceable for all sizes of hands.
[Illustration: _Fig. 152._]
=329.= =Clip for Holding Escapewheels while Cleaning.= A mere
inspection of M, Fig. 152, will make the arrangement of this little
tool evident. The fork is made of a piece of brass rod and its two arms
are elastic, a handle being screwed into the lower extremity.
Two small steel jaws are fixed to the upper ends inclined towards each
other, and, in using the tool, it is only necessary to press with two
fingers on the heads of the screws, when the jaws will open. Having
placed the escape wheel pinion between them, the wheel will be firmly
held so that its teeth can be easily cleaned, etc.
[Illustration: _Fig. 153._]
=330.= The appliance shown in Fig. 153 can be used for a similar
purpose, and is further especially serviceable for holding an
escape-wheel that is not riveted to its pinion. It consists of two
parts, a handle T, shown separate at _t_, which is drilled throughout
its length and tapped externally at the portion _t_, and a collar or
nut D, the end of which is traversed by two cuts at right angles that
resemble the letter =T= in section. If the tool is intended for holding
escape-wheels that have three instead of four arms, this cross must be
replaced by three radiating grooves of similar section. The position
occupied by the wheel is indicated by the dotted lines _r r_, and it
will be evident that, when the flat end of T is screwed up against this
wheel, after dropping it into the cross and slightly turning round
the axis as in a bayonet joint, it may be firmly held. The safest
mode of introducing the wheel is by holding it on a broach, which is
subsequently removed.
[Illustration: _Fig. 154._]
=331.= =Tool for Testing the Truth of a Cylinder Escapewheel.= The
small tool shown at D, Fig. 154, can be advantageously used in place
of the plain arbor commonly employed for testing the equality of the
spaces in such a wheel. The plate D, which may be mounted on three
feet, is traversed at its center by the smooth conical portion _f_
of the screw _f v_, tapped somewhat tightly into a cock fixed to the
other side of the plate. There is a radial slot, _a c_, cut in the
plate large enough to allow an escape-wheel pinion to move freely. An
inspection of the figure will make evident the manner in which the tool
is to be used: a wheel being placed as shown, or with reverse side
upwards, is made to slide towards the center, gradually raising the
screw until the largest space is found to admit _f_ with contact at
both sides. All the smaller spaces are then carefully opened until they
admit the cone in the same manner as the largest.
=332.= _Novel tool for the same purpose._ When the spaces are adjusted
in the manner explained above, or if the length of the teeth is
measured in a narrow gauge plate, there will nearly always remain a
certain degree of irregularity in the teeth. A more efficient means
would be for the gauge to embrace both a tooth and space, and this
condition is satisfied by the following appliance.
[Illustration: _Fig. 155._]
The slide _k k_, Fig. 155, is dovetailed into a plate, level with
its surface, so that _k k_ can be moved in a vertical direction by a
screw; it is perforated with a series of holes of gradually decreasing
diameter. To the same plate are also fixed: (1) a smooth tongue, _b_,
with a foot and screw; and (2) a second tongue, _j_, terminating in an
index _x n_, which is movable about a pivot, _x_, and held against a
pin in the plate by a light straight or spiral spring. The extremity,
_n_, traverses a graduated arc.
Having introduced the pinion of the wheel, or the arbor on which it is
held, into a hole of the slide that it fits without shake, and brought
this hole to the position indicated in the figure, apply a slight
pressure to the wheel in the direction of its rotation. With one tooth
resting against _b_ the tongue _j_ will be held by the spring against
the next and the reading of the index is to be noted accurately.
Withdraw the wheel slightly, and, placing the succeeding tooth against
_b_, take a second reading, and so on around the entire circumference.
Of course, the delicacy of the instrument will be increased by
lengthening _x n_ in comparison with _x j_.
[Illustration: _Fig. 156._]
=333.= =Tool for Removing Studs.= Fig. 156 represents a small tool
which may be employed for this purpose. It consists of a thick strip
of metal, C, spreading out like the letter T at the end which is not
shown, so as to form two feet, the screw, _j_, being a third, so
arranged that the T rests horizontally. The disc, _d_ (shown also
in plan), rotates on the screw, _j_, and is partially enclosed in a
horizontal slot. Around the circumference of _d_ are four rectangular
notches of different sizes. The holes indicated by black dots on the
plan receive the point of the screw, _v_, which clamps the disc when
the notch corresponding in size with the stud to be removed has been
brought under the small cone projecting from the spring, _b_; the other
end of _b_ is fixed to the T-shaped piece, C. The mode of using this
little instrument will at once be evident. Resting the right arm on the
bench, and, with the left-hand, bringing the wing of the cock above the
notch in _d_, the other hand presses upon the milled button of _b_,
forcing the conical pin against the stud and thus removing it from the
cock. The screw, _a_, can be adjusted so as to prevent too great force
being applied.
[Illustration: _Fig. 157._]
=334.= =Tweezers for Removing Studs.= One form is shown in Fig. 157.
The upper arm, H, is bent downwards as indicated at _g_. The lower arm
is shorter and carries a separate piece, _n m_, which slides under two
screws, _s_, and is pressed forward by a spring, _r_. The action will
be easily understood; the extremity, _m_, rests against the stud, and
_m n_ is forced backwards until the point, _g_, is exactly over the
stud pin. A simple pressure of the finger will then suffice to remove
the stud.
A still more simple pair of tweezers for this purpose may be made by
filling a square notch in the end of one prong of an ordinary pair with
broad noses, and setting a pin opposite to its center in the end of the
other prong.
=335.= =Staking Tool.= The modern staking tool will perform the same
work as the last two tools described and many other operations. It
consists of a shifting table, around which holes of various sizes are
arranged in a circle, so that any desired hole may be brought under
a suitable punch moving in a vertical holder. Usually twenty-four
tempered steel punches and four stumps are provided, which will be
found sufficient to cover all the operations in the ordinary run of
watch repairs, and the ingenious workman can from time to time add
to these by making punches in his spare moments, if he finds from
experience that he is in need of punches of a different shape. Fig. 158
illustrates the Johanson combination staking tool, on the front end of
which a hairspring stud indicator is arranged.
[Illustration: _Fig. 158._]
=336.= The staking tool can be used as a cannon pinion tightener by
making a punch for it having a blunt chisel edge. When a cannon pinion
is placed on a stump which is slightly dished in that portion of its
face opposite to the punch, and the punch gently struck with a hammer,
it will be sufficiently contracted to insure the requisite adherence to
the set-hands arbor. If fears are entertained lest the pinion should be
cracked with the blow, it may be placed loosely on an arbor and held in
position.
=337.= It may also be used to advantage for tightening the set-hands
arbor in the center or cannon pinion, but care must be exercised or
the arbor may be bent so that the minute hand which it carries passes
nearer the dial at one place than another.
An arbor that is too loose is introduced into a suitable stump and
at the top and bottom of the slack portion two punch marks are made
opposite one another. The punch having a conical or three-sided point,
will occasion an expansion of the metal round each mark; if a smooth
file be passed over the surface so as to remove the burr, which would
not offer any permanent resistance, sufficient projecting metal will
be left to secure a sound and lasting friction when a little oil is
applied.
If the arbor is well supported immediately beneath the punch, it
will not be distorted by any moderate impact. It is advisable before
operating on the metal to ascertain its degree of hardness.
=338.= It may also be used as a pinion riveting tool. The pinion,
with its wheel in position, is placed on the hardened steel stump,
the end to be riveted being upwards. The riveting is then struck
with the polished end of a hollow punch. If it be required to spread
the riveting, a punch must first be used that is rounded from within
outwards, to be followed with a perfectly flat punch. A little practice
will at once enable a workman to select the best form of punch.
The stump should be very hard and polished, funnel-shaped downwards
and carefully fitted to the bed, so as to be firm and central with the
punch. If these precautions are not taken the pinion will spring and
the riveting will be imperfect.
=339.= The staking tool may also be used for closing up barrel holes,
screw-holes, etc. In repairing watches it is often found that the
screws hold badly or not at all, and the holes at times cannot be
satisfactorily bushed. In such cases it becomes necessary to close
them, an operation which any intelligent workman can perform very
well in the following manner: Make a stump rounded at the top and
provided with a pump-center. This can be merely a pointed steel rod
that passes through the stump from below with slight friction, and
is forced upwards by a light spring fixed by a screw, so that, on
undoing the screw, the rod can be removed. The one pump-center can be
used for various stumps as the openings are funnel-shaped downwards.
Center the hole to be closed by means of the pump-center, then bring
down the hollow punch and strike it as in riveting a pinion. A small
circular groove will be formed around the hole, which, if the punch
is in good order, will be perfectly even. The form of the punch is
very important; the watchmaker must decide for himself by trial as to
the most convenient shape. The thickness of the ring of metal may be
modified; it is rounded off in a semicircle by some, and curved inwards
or outwards by others.
Instead of a pump-center below we have used punches that were
themselves provided with a pump center and helical spring. Either form
gives satisfactory results.
The holes of barrels can be closed with a punch that is only depressed
at its center enough to avoid the point of the pump-center. When the
face is more or less rounded the hole will be closed by forming a cup
as with a chamfering tool. The tool may then be enlarged if requisite
with a round broach or an arbor covered with white wax. It will thus be
hardened, and the cup-shaped recess will serve to retain the oil, while
the somewhat thinner hole will probably be in a condition to resist
friction as long as formerly.
When the hole is of moderate thickness, and it does not require much
reduction in diameter, this method will be found satisfactory; barrels
that have been thus treated have been found to stand ten years without
appreciable wear. When the metal is thicker, however, the spreading
inwards is very slight, and there is some danger, in using a round
broach to do it, of straining the metal or detaching the central ring
of the barrel or its cover.
It should be observed that the methods explained above are absolutely
useless for closing pivot-holes, and should only be resorted to for
barrels, on an emergency.
=340.= =Drifting Tool.= This appliance, shown in Fig. 159, is very
useful for making holes of round, oval or square, or, indeed, any
required form. It takes the place of a punching machine for light work.
[Illustration: _Fig. 159._]
The punch, or “drift,” is screwed into the stock C C′. A pin, _p_,
fixed in C C′ prevents its rotation while allowing an end motion
along the slot _m_ _n_. The end C′ is hollowed out to receive the
point of a screw, B, and a pin, shown near C′, is received in a groove
turned in B, thus enabling it to draw the stock in the direction C
C′. The part H is gripped in the jaws of a vise, and a strong handle,
E, is used to advance the screw B B′. With a tool about three times
the size of the figure there is no difficulty in punching the eyes of
mainsprings, square holes in stop fingers, etc., and it can be made by
an apprentice. Of course its strength depends on the pitch of the screw
and the radius of the handle E.
=341.= For heavier work it will be necessary to resort to the punching
machine. There are several constructions in use, but the most usual
is essentially the same as that of the tool just described. The screw
works vertically in a strong bridge that is fixed to the bed in which
the counterpart of the punch is held. Great use is made of this machine
in factories at the present day, almost every part of a watch being in
the first instance roughly shaped by its means. Indeed, thin metal is
often left as it comes from the punch, and very perfect crossings of
wheels, etc., are thus produced.
Steel does not cut well in the press unless it is soft and homogeneous,
and the final dimensions of the object can be more nearly approached
according as these conditions are satisfied. Attempts have been made
to cut levers, etc., of the exact dimensions required, but it is
better to leave a slight excess of metal to be afterwards removed by a
mill cutter or other means. The crossings of steel lever and cylinder
escape-wheels are punched out, but the metal used is of special
excellence. Before introducing a piece of steel into the press it is
advisable to remove any scale, etc., by pickling, or with a file.
=342.= =Draw-Plate.= Every watchmaker should possess a plate for
drawing round wire so as to be able to obtain it of any required
diameter. They are to be had at all material houses. In bushing holes
in a brass plate, it not unfrequently happens that the brass used for
the bushing is not of the same color as the plate. To avoid such a
difference cut off a piece from a plate of the same color and round
it by hand, making one end to taper. Fixing the draw-plate in the
vise, pass this end through one of its holes, and, gripping it in the
hand-vise, pull the brass through the plate. Continue this operation
through successive holes until the requisite thickness is attained.
No special precautions are necessary, further than keeping the holes
well greased and annealing the brass from time to time so as to
counteract the hardening caused by the operation.
Such a plate can also be used for steel wire, and plates with holes of
special form, for example those for drawing click and pinion wire, are
well known in the trade.
[Illustration: _Fig. 160._]
=343.= =The Grammaire, or Dividing Plate.= This tool is shown in
Fig. 160. To mark out the crossings of a wheel, etc., fix it by the
conical-headed screw _t_ to the middle of the plate, on which are
traced a series of concentric circles (not shown) divided into 6, 8, 10
and 12 equal parts. By laying the little ruler _r_ _r_ over the wheel
blank and using these division marks as a guide, 3, 4, 5 or 6 radii can
be drawn to serve as guides for cutting out the arms.
If it is desired to indicate the width of the arms instead of a mere
central line, a series of holes must be drilled at the division marks
and screws with tapered points tapped into them from below. Resting the
ruler against these cones, the arms can be drawn of any required width,
according to the distance to which the screws project. No further
explanation is necessary, for the figure shows: (1) a grammaire adapted
to mark out a four-armed wheel, these arms being indicated by the
dotted lines; and (2) the small ruler _r_ _r_ cut away at the middle so
as to avoid coming into contact with the conical-headed screw.
[Illustration: _Fig. 161._]
=344.= =Jewel-resetting Tools.= Hopkins’ patent jeweling and staking
tool, shown in Fig. 161, is an ingenious device, and one that will be
found very useful to the watch repairer. As the spindle, or handle, to
which the cutters and burnishers P P P are attached, is sustained in
upright position when in use, by the long bearings through which it
passes in the upright F, independently of the lower center, the hole
to be cut may be centered either from above or below as preferred; and
the depth to which it is desired the cutter shall work is regulated
by adjustment of the sliding collar E, and this being a correct
uprighting, as well as jeweling tool, with it a pivot hole, or a jewel
setting, the correct center (upright) of which has been lost, may
readily be corrected, or its true center again found, and, what in some
cases would be a very desirable consideration, by careful manipulation
with the cutter, which is under perfect control of the operator, the
position of jewel settings may be changed so as to alter the depth of
locking of the wheels to any desired extent. To regulate the depth to
which it is desired a cutter shall work below the surface of a plate,
lower the spindle D until, when moved out sufficiently far, the end
of the cutter will rest down on the top of the plate to be operated
upon, and fasten it there by lightly tightening the screw K; this done
adjust and fasten the collar E on the spindle D, to the same height
above the top of the upright F as it is desired the cutter shall work
below the surface of the plate on which it now rests. This, when the
spindle D has been again set free by loosening the screw K, will of
course allow the cutter to sink into the hole to be operated upon
to the exact distance the collar E had been set above top of F. In
adjusting the collar, E, the graduated wedge No. 4, or the jewel to
be set, as preferred, may be used as a gauge. The burnishers, No. 9,
are used both for opening and closing settings; the same burnisher,
having chosen one of proper size, is used for both purposes; the side
being used for opening the setting, and the beveled and rounded end
for burnishing it down again over the jewel. The pieces 13 and 14 are
made to fit in the lower end of the spindle D (the cutter P having been
removed), same as an ordinary drill-stock, and are used for burnishing
the edges of a jewel setting down flat over the jewel, countersinking
screw heads, giving end-shake to wheels, etc.; and being easily made,
any one owning the tool can make these for himself, of forms and sizes
to suit the particular work in hand. For uprighting purposes, withdraw
the spindle D and substitute No. 5, the rings, No. 3, being intended
for laying the work on, on the tool bed. For upright drilling through
watch plates, mark the place to be drilled (prick punch it slightly)
with the cone point of No. 5; which done turn the spindle No. 5 upside
down and rest the upper end of the drill in the countersink in its end,
the drill being operated with a fiddle bow acting on a collet placed
on its shank for the purpose. For cutting off bushings level with a
watch plate, either a cutter of the No. 13 or 14 class, or one of the
P cutters can be used. For staking or riveting wheels upright on their
pinions, lay the stake No. 7 level on the tool bed (the center M having
been fastened down out of the way), and with No. 5 center accurately
the hole to be used in the stake, and fasten it there by means of the
clamps N; then remove the cone end of No. 5, and place a punch with a
hole in its end of the required size, on the part _m_, and proceed as
in an ordinary upright staking tool.
=345.= =Tool for Flat Polishing.= A thick brass plate is provided with
three strong screws arranged in triangular form (G, Fig. 162), and
far enough apart to ensure that, if the plate is reversed and rests on
their heads, it will remain flat when moved by hand over a polishing
surface.
[Illustration: _Fig. 162._]
The screws should fit tightly or be provided with lock-nuts.
We believe that every watchmaker must be acquainted with this little
tool. The object to be smoothed or polished is fixed with shellac or
sealing-wax to the middle of the triangle formed by the screws; the
level is then adjusted so that, when resting on a flat surface, the
object to be polished coincides exactly with it. The polisher (for
example, a sheet of ground glass) is charged with oilstone dust or
polishing rouge, and the object is passed over it until perfectly flat
and smooth.
=346.= For smoothing, it is best to use a large sheet of iron or steel.
For polishing, copper or bronze is preferred. Ground glass may be
employed for both operations; it must be hard and perfectly flat.
A disc rotating in the lathe or mandril, etc., is often used.
The tool may be inverted and rest firmly on a cork, the polisher being
then moved backwards and forwards by hand, and always in contact with
the three screws.
It is best to use pith for cleaning the polished surface; in its
absence use soap, then wash and dry with a soft linen rag. The object
is detached by heating the tool, and is cleaned by boiling in alcohol;
afterwards pass through pure alcohol at the ordinary temperature and
dry.
=347.= This tool can be employed for polishing small surfaces, such as
the end of a rod, of a barrel-arbor or a screw-head, as well as for
those of greater extent. But it appears needless to enter into further
detail.
Instead of three screws some workmen only use two, at some distance
apart. The object to be polished, being placed at the third corner of
the triangle, takes the place of the remaining screw.
Lastly, if a band be fitted to one side of the brass plate, as shown at
_b_, Fig. 162, and held by two screws, it will often be of service as a
clamp for fixing the object, as at _s_.
=348.= Flat pieces can be polished on a revolving lap worked by the
foot, being simply held in the hand or in a piece of soft leather; but
a certain amount of practice is needed in order to do this successfully.
ACCESSORIES
AND MISCELLANEOUS OPERATIONS TO BE PERFORMED IN THE UNIVERSAL HEAD.
=349.= With a view to simplify the work, we will here give, in a
collected form, a number of operations that may be performed in the
mandril, or universal head, among which the practical watchmaker will
easily be able to distinguish those that can be done in the ordinary
lathe; we will also describe numerous accessories that the workman
should make for himself, if he is desirous of making his mandril or
universal head still more generally useful.
[Illustration: _Fig. 163._]
=350.= Prepare a number of chucks of the form shown in Fig. 163. Some
of these carry a small bar with screws, by which an object may be
clamped firmly to the chuck, an arrangement which is also shown at A,
Fig. 163; others have a hole drilled through their axis; others again
have a projecting arbor, etc. They may also be made with a flat face
on which to cement objects in the ordinary manner.
[Illustration: _Fig. 164._]
As it is often necessary to have a considerable surface to cement, for
example, a watch-plate, one or more may be made of the form shown at T,
Fig. 164. The lower plate being clamped in the dogs, the disc _e_ will
be free. If this disc be made of bronze or steel it may be used as a
lap; if of brass, it may be turned true and used as a wax chuck, etc.
The chucks should, as far as possible, be well made, so that they can
be truly centered by means of the pump-center.
TO CENTER AN OBJECT.
=351.= When there is a hole at the center on the side towards the
face-plate, in the universal head, as is usually the case, it is only
necessary to place this hole over the point of the pump, pressing it
inwards, and then to clamp the object in the dogs; the pump is then
drawn within the body of the arbor. Very often, however, there is no
central hole, or there is only a mark on the face that is towards the
cutter; in such a case it becomes necessary to center from the front or
by the circumference.
=352.= =To Center from the Front.= If the object is held by wax on a
plate, it may be centered as in the ordinary lathe while the plate is
hot, by resting a piece of pegwood on the T-rest with a point placed in
the central hole, and observing whether its free end remains stationary.
After the plate has cooled, the accuracy of the centering should be
tested by means of a long piece of pegwood which rests on the T-rest
brought close up to the object. The pegwood is held parallel to the
lathe-bed, and, if the centering is satisfactory, its outer end will
not move. The detection of any slight movement is greatly facilitated
by placing some fixed object close to the free end of the pegwood. If
a motion is still observed the centering is imperfect, and must be
corrected in the manner explained below (=354=).
=353.= _Perrelet’s method of Centering._ In principle, this is
identical with the one just described; but the pegwood index is
replaced by the small apparatus shown in Fig. 165.
[Illustration: _Fig. 165._]
A hollow cylinder, of which _a c c a′_ is a section, is firmly held by
friction by its portion a _b b′ a′_ in the tailstock. In the front of
this cylinder is fixed a steel ring that is thick at the circumference
and tapers inward, so that the central hole has a cutting edge. The
two black triangles represent a section of this ring. The rod _r_ _n_
passes without play through this hole, and carries a projecting ring
at _s_ to determine the distance to which it enters the collar _c c_;
there is also a small key that corresponds with a nick in _c c_, and
thus prevents rotation.
An inspection of the figure will show that, when _s_ rests against _c
c_, if the finger be placed on _r_ and communicate motion to it, the
rod _n r_ will be able to oscillate in any direction, and to an extent
limited by the diameter of the hole in the cylinder.
The error in the centering at _r_ will be multiplied at _n_ in the
proportion of _n s_ to _s r_; thus if _n s_ is ten times _s r_, the
motion at _n_ will be ten times as great as the actual error at _r_.
=354.= The instrument is used as follows: The object to be centered
being placed between the jaws, having the centering spindle in
position in tailstock. Slide tailstock towards the face-plate until the
point _r_ of the rod enters the hole, or central mark of the object,
and, setting the T-rest close to the point _n_, rotate the face-plate.
If the centering is exact, the point _n_ will remain stationary. If _n_
moves to and fro, give a gentle blow against the edge of the object,
which should not be held firmly in the dogs; the blow must be on the
side opposite to that at which _n_ shows the greatest deviation from
the point of reference. Repeat the process until the centering is
perfect or sufficiently accurate; then clamp the dogs firmly, taking
care not to disturb anything.
In centering from a jewel hole, an aluminium rod _n s_ may be employed
on account of its lightness, and it may be terminated in an ivory cone
at _r_.
=355.= There is one precaution to be observed, as it facilitates the
use of this appliance; it is advisable that the portion _a b b′ a′_
of the cylinder be somewhat long and well made, in order that, while
being in the first instance inserted in tailstock up to the shoulder,
the cylinder may be partially withdrawn and still held firmly. The
reason for this is as follows: When the tailstock is pushed along, a
considerable amount of friction resists its motion, and, as the hand
cannot always control this motion, it may happen that _r_ comes up
against the object with some force. To avoid this, bring the point near
the hole and then rotate the collar in the tailstock so as to gently
withdraw it to the requisite amount. The cylinder may, if desired, be
fixed by a small screw after the point _r_ has been set in position.
[Illustration: _Fig. 166._]
=356.= =Another Centering Device.= The centering indicator shown in
Fig. 166 will also be found useful for testing for exact center. The
body of the indicator is made of sheet brass, and should be about five
inches long by two inches in width at the larger end. The shank _C_
is made to fit in rest holder, and is either riveted or soldered to
the body; _R_ is steel or copper wire sharpened to a fine point, and
balances on a pivot at 1; _B_ is a clock hand pivoted to the body at
1; 2 and 2 are pivot joints only, and do not go through the body; _C_
will perhaps give a better idea of the end _R_. To center with this
tool, unscrew your rest and remove it, then place the shaft _C_ in rest
holder and adjust it till the needle point _R_ touches the top of hole,
as shown at _A_. The index hand will then note the variations as the
head revolves. If too low, the hand will point above center, and if
high, vice versa.
=357.= =To Center from the Circumference.= Two cases may occur:
Either the entire rim of the object is exposed, as when the teeth are
to be cut in a wheel blank; or the rim can only be used as a means
of determining the center, as when a barrel has been bushed with an
undrilled bushing.
=358.= The tool shown in Fig. 166 may also be used for the test if the
short end of arm R rests against the under side of the object that it
is desired to center.
=359.= When it is required to drill or merely to center the hole in a
wheel, barrel, etc., that does not run true, clamp a piece of sheet
brass in the dogs and turn out a sink that will exactly receive the
wheel, etc., but allowing it to project slightly. Now unscrew one dog
and advance it a little, so as to grip the edge of the object as well
as the plate; move the other dogs inwards in succession, and it will
only remain to drill or true the hole with a suitable drill.
UPRIGHTING AND DRILLING.
=360.= =When the Lathe is Provided with a Tailstock.= Let it be
required to mark and drill a pivot-hole in the cock when the plate-hole
is accurately centered by means of the pump-center. Place the tailstock
in position on the lathe-bed, and mark the position of the hole with a
center, as in an ordinary uprighting tool; then, if the hole is to be
very fine, make it with an ordinary pivot-drill.
If the hole to be drilled is somewhat large, it may be drilled with the
twist drill, the bed of the lathe being, as usual, horizontal.
=361.= =When the Lathe is not Provided with a Tailstock.= In such a
case it is possible to upright and drill by using fine drills, and
making points so formed as to take the place of the cutter. Or a stock
may be made to receive drills, points, etc., and it may be well here
to remark that stocks of the same form are convenient for receiving
chamfering or sinking tools.
[Illustration: _Fig. 167._]
This stock is shown in Fig. 167. An inspection of E _c_ will suffice
to show its form, and it may be used for holding either a drill or a
marking point, or a small hollow center in which to support a pivot
drill.
The following method should be adopted for securing accuracy in the
adjustment of these stocks:
There must be no shake of the stock in the tool-holder; it is
especially important to avoid any displacement during the act of
clamping. If there is any reason for doubt on this point, drill a hole
at the foot of the cutter in which an index, _y_, can be temporarily
inserted; any displacement can be detected by its deviation from a
fixed mark. As a rule, however, there will be no occasion for doubt if
the plate that is screwed down upon the stock is parallel to the bed of
the tool-holder.
The cutter is then replaced by a stock of the form shown at E′, in
which a hole has been previously drilled to receive the drill or other
bit, but somewhat smaller than it is required finally to be. The
pump-center must now be replaced by an accurately fitting piece B that
terminates in a short semi-cylindrical drill.
It will be evident that if the mandrel be revolved, and, at the same
time, the tool-holder advanced towards this drill, the hole in the
stock E′ will be enlarged and smoothed, and its axis will accurately
coincide with that of B. Any drill, chamfering tool, etc., that has
been turned true, will, therefore, on being inserted in the stock,
prove to be strictly in the axis of the lathe.
[Illustration: _Fig. 168._]
=362.= =To Drill a Series of Holes.= Mount on a stock similar to that
just described, a small frame carrying a drill-stock, as shown in Fig.
168. If this be fixed in the slide-rest in place of the cutter, it can
be used for drilling a hole or a series of holes previously marked out,
or, if the pitch of the transverse screw of the slide-rest is known,
for a series of equidistant holes in a horizontal line. When it is
required to drill a series of holes in a circle, as, for example, in
the escape-wheel of the pin-escapement, bring the point of the drill
onto the circumference and then proceed as when using the ordinary
wheel-cutting engine provided with a vertical drill-holder, taking care
to fix the face-plate by means of an index.
This index should have a means of slightly modifying its length,
so that the point of the drill may always be brought into exact
coincidence with the points that have been previously marked on the
object.
It will be observed that, if the drill were replaced by a round milling
tool, the U’s of a cylinder escape-wheel might be polished, or, indeed,
cut, the concave ends of the teeth of the star-wheel in a Geneva
stopwork could be corrected, etc. But it is unnecessary further to
insist upon the many uses to which this form of tool can be applied.
=363.= =To Cut the Teeth of a Ratchet, Minute-Wheel, Etc.= When the
face-plate is divided on the circumference, it is easy to cut the teeth
of an ordinary wheel of a timepiece, escape-wheel, barrel ratchet, to
cut or true a star-wheel for the stopwork, etc. After mounting the
wheel on a chuck and carefully centering it, replace the cutter by a
small revolving cutter-frame after the model of that shown in Fig. 168.
The stock _d_, shown in both plan and elevation, carries a piece _c_
at right angles, which has a slot cut throughout its length. In this
slot a U-shaped support can be clamped by a nut in any position. The U
portion forms a bearing for a cutter, such as is shown at _f_ in the
figure, and the axis projects so as to receive a ferrule for rotating
the cutter.
It will be evident that, with such an arrangement, the height of the
cutter can be adjusted in accordance with the teeth to be cut.
=364.= =To Cut a Circular or Elliptic Groove.= For this purpose no
special accessory is needed; an ordinary cutter will suffice.
[Illustration: _Fig. 169._]
Let _a b c d_, Fig. 169, be the form of the required groove. Mark a
series of centers so that circles struck from them will just overlap
one another, and at the same time nearly reach the edge of the groove.
Then turn out all the circular sinks, indicated by shaded lines, to the
required depth.
Center the plate by the point _o_ from which the arc _a b_ is struck;
now bring the cutter to such a position that its outer cutting edge
coincides with the arc _a b_, and bring it against the plate; set the
face-plate in motion, not, however, by using the treadle, but by the
hand at its circumference, and traverse the arc from _b_ to _a_; then
withdraw the cutter. By this means the projecting angles, left white
in the figure, will be removed, and a clean edge will be left to the
groove.
As an operation of this description will not present any difficulty,
further explanation appears unnecessary; for the information above
given will enable any watchmaker to make curved grooves of the kind
indicated.
If it is required to smooth the surface of the groove, replace the
cutter by a pegwood stick that can be rotated with friction, and
the end of which just fits into the groove, charging it with pumice
or other stone and oil. One hand moves the face-plate backwards and
forwards, while the other rotates the stick.
[Illustration: _Fig. 170._]
=365.= _To Cut the Cylinder Escape-Wheel Cock Passage._ As a rule the
cock is cemented, inverted, to a wax chuck, and the passage cut or
enlarged on the lathe. It is more expeditious to use a plate provided
with a clamping bridge, as shown at Fig. 170. The face-plate should be
made to oscillate backwards and forwards by hand, and not rotated by
the wheel.
=366.= =To Make a Straight Groove.= _First method._ The tool devised by
M. Chopard, director of the school of horology at Besançon, and shown
in Fig. 171, is used for this purpose. As will be seen, it consists of
a small lathe which is adapted to the slide-rest as follows:
[Illustration: _Fig. 171._]
Two pins, _a a′_, are planted in the top of the tool-holder, the
cutter together with the plate by which it is clamped having been first
removed. Holes drilled in the frame _f f_ fit accurately onto these
pins, while a screw, _h_, passing through an intermediate hole, affords
a means of firmly fixing the apparatus to the tool-holder M.
This tool should satisfy the following conditions: The arbor C should
fit into a recess that receives a cutter, but without coming into
contact with it; this arbor should be parallel to the bed of the lathe;
and, lastly, the axis of C should be on a line with the lathe center.
=367.= Having set this little appliance in position, trace on the
watch-plate two lines indicating the directions of the sides of the
groove as well as lines fixing its length. Now place the plate in the
dogs, setting the point of the pump-center anywhere on the line drawn
along the middle of the groove. Turn the plate so that this line is
horizontal, and fix it in any way that is convenient.
The arbor C carries a revolving cutter _k_, which can be changed as
desired, and is held in position by the clamping screw _d_. Assume
that the diameter of this cutter corresponds exactly with that of
the required groove; advance it towards the plate, turning the wheel
rapidly, the cord being round the ferrule _b_; a circular sink will
thus be formed in the plate of the same diameter as _k_.
When this has been cut to a sufficient depth, the tool is moved
parallel to the face-plate, and the cutter _k_, continuing its movement
of rotation, will now cut, not with its extremity _i_, but with its
sides. It will thus form a straight groove of any desired length.
=368.= The cutter is a three-sided prism, or it may have four sides
with four cutting edges on the sides, and only one cutting edge at the
extremity _i_. If it is preferred to retain only the two acting edges
that start from either end of the cutting edge _i_, they may be made
more acute, and the other pair reduced by means of a file.
[Illustration: _Fig. 172._]
=369.= _Second method._ This is simpler than the one just considered.
At the end of a rod G, Fig. 172, which takes the place of the cutter
in the slide-rest, a plate _p_ is fixed. A line is drawn across the
face of this plate in such a position that, when G is clamped in the
tool-holder, this line is horizontal, and in the plane that contains
the axis of the pump-center.