Watch and Clock Escapements

that such a thing may be all right in theory, but will not work in practice. This statement has no foundation in fact. If a given mechanical device

e such drawings to scale, and add a specification stating the materials to be employed, we leave only the mer

who repairs such watches to know and be able to carry out, in order to put them in a condition to perform as intended by the manufacturers. It is not knowing these lines which leaves the average watchmaker so much at sea. He cuts and moves and shifts parts about to see if dumb luck will not supply the correction he does not know how to make. This requisite knowledge does not consist so much in knowing how to file or grind as it does in discriminating where such application of manual dexterity is to be applied. And right h

S OF THE CYLIN

, although Saunier, in his "Modern Horology," delineates a twelve-tooth wheel for apparently no better reason than because it was more easily drawn. We, in this trea

a balance staked on to it. Fig. 123 shows the cylinder removed from the balance collet. Figs. 124 and 125 show the upper and lower plugs removed from the cylinder. Fig. 126 is a horizontal section of Fig. 122 on the line i. Fig. 127 i

r or Mai

Half

-Co

-Small

. -Balan

pper

ower

nce Lip o

Lip of

ankin

-To

-U

alk of

-U

int of

el of

of the cylinder and one on the inside of the shell. As we shall show later on, the cylinder escapement is the only pos

s dead on the outer or inner surface of the half shell until the action of the balance spring has brought the

ased or escapes from the inside of the half shell of the cylinder A, said cylinder must turn or revolve a little in the direction of the arrow j, and also that the next succeeding tooth of the escape wheel will engage the cylinder on the outside of the half

n alternate directions we must arrange to have these half-tooth movements exactly alike, or, as stated above, of equal angular values; and also each impulse must convey the same power or force to the balance. All escape wheels of fifteen teeth acting by half impulses must impel the balance during twelve degrees (minus the drop) of escape-wheel action; or,

ent lifts. This last division is only an imaginary one, as the real lift is the one to be studied and expresses the arc through which the impulse face of the tooth impels the balance during the act

and cylinder that each half of the tooth space shall give equal impulses to the balance with the minimum of drop. To do this we will make a careful drawing of an

E CYLINDER

plan is to employ a protractor, which serves the double purpose of enabling us to lay off and delineate any angle and also to measure any angle obtained by the graphic method, and it is thus by this graphic method we propose to solve very simply some of the most abstruce problems in horologica

ld up from the underlying principles. In the drawings for this purpose we shall commence with one having an escape wheel of 10" radius, and our first effort will be the primary drawing shown at Fig. 129. Here we establish the point A for the center of our escape wheel, and from this center sweep the short arc a a with a 10" ra

ooth. That portion of the line b g which lies between the points b and n represents the measure of the inner diameter of the cylinder, and also the length of the chord of the arc which rounds the impulse face of the tooth. We divide the space b n into two equal portions and establish the point e, which locates the position of the center of the cylinder. From A as a center and through the point e we sweep the arc e' e', and it is on this line that the points establishing the center of the cylinder will in every instance be located. From A as a center, through the point n we sweep the arc k, and on this line we locate the points of the escape-wheel teeth. For delineating the curved impulse faces of the escape-wheel teeth we

S GAINED

wn in Fig. 129. It will be seen on inspection that the angular motion imparted to the cylinder by the impulse face of the tooth when curved as shown, is greater during the first half of the twelve degrees of escape-wheel action than during the last half, thus giving the escape wheel the advantage at the time the balance spring increases its resistance to the passage of the escape-wheel tooth across the lip of the cylinder. Or, in

IAMETER OF

viders set to embrace the extent from the point n to the point c we set one leg at the point b, and with the other leg establish on the arc k the point h. We next draw the line b h, and from the point b draw the line b f at right angle to the line b h. Our object for drawing these lines is to define the heel of our escape-wheel tooth by a right angle line tangent to the circle w, from the point

termed, the "actual lift." This latitude governs to a great extent the angle A b g, which we gave as sixty-four degrees in our drawing. It is well to understand tha

inder and the measured (by lineal measure) height of the impulse plane. Or, to be more explicit, we measure the radial exten

ith the advantages of accurate micrometer calipers now possessed by the horological student it is an easy matter to get at the angular extent of the real lift of any

se we have a new cylinder to put in; we have the old escape wheel, but the former cylinder is gone. The old-style workman would take a round broach and calculate the size of the cylinder by finding a place where the broach would just go between the teeth, and the size of the broach at this point was supposed to be the outer diameter of the cylinder. By our method we measure the diameter of the escape wheel in thousandths of an inch, and from this si

G A CY

s d and b we define the inside of our cylinder. We next divide the chord d b into eight parts and set our dividers to five of these parts, and from e as a center sweep the circle h and define the outside of our cylinder. From A as a center we draw the radial line A e'. At right angles to the line A e' and through the point e we draw the line from e as a center, and with our dividers set to the radius of any of the convenient arcs which we have divided into sixty degrees, we sweep the arc i. Where this arc intersects the line f we term t

s has established the fact that this is about the right angle to employ, while in smaller watches it frequently runs up as high as twenty-five. Althou

ER PROPER

in which just one-half is cut away, that is, the lips are bounded by straight radial lines, we can also conceive of the relation and position of the parts shown in Fig. 130. The first position of which we should take cognizance is, the tooth D is moved back to the left so as to rest on the outside of our cylinder. The cylinder is also supposed to stand so that the lips correspond to the line f. On pressing the tooth D forwar

e inner angle. Now it is evident that it would require greater force to propel the cylinder by its inner angle than by the outer one. To compensate for this we round the edge of the entrance lip so that the action of the tooth instead of commencing on the outer angle commences on the center of the edge of the entrance lip and also ends its action on the center of the entrance lip. To giv

LAR EXTENT I

ngular motion of the cylinder, which would be lost if the tooth commenced to act on the inner angle and ended on the outer angle of the exit lip. This arc is a little over six degrees, and if we add a trifle over three degrees for rounding we would account for the ten degrees between the lines f and p, Fig. 131. It will now be seen that the angular extent is 196 degrees. If we draw the line w we can see in what proportion the measurement should be made be

y one position for the center of the cylinder, and that is so that the center of the pivot hole coincides exactly with the center of the chord to the curve of the impulse face of the tooth or the point e, Fig. 130. Any adjustment or moving back and forth of the chariot to change the depth could only be demanded where there was some fault existing in the cylinder or where it had been moved out of its proper

A WORKI

ds riveted to the U arms to support the teeth. This U arm is attached to the long arm we have just mentioned. A flat ring of heavy sheet brass is shaped to represent a short transverse section of a cylinder. This segment is mounted on a yoke which turns on pivots. In making such a model we can employ all the proportion

PE OF CYLI

so large that we can establish upon it the center of the arc which represents the periphery of our escape wheel, as we have at our disposal two plans by which this can be obviated. First, placing a bit of bristol board on our drawing-board in which we can set one leg of our dividers or compasses when we sweep the peripheral arc which we use in our delineations; second, making

shell of the cylinder as shown occupies 196 degrees or the larger arc embraced between the radial lines k and l. In drawing the entrance lip the acting face is made almost identical with a radial lin

r shape, especially when he remembers that the thickness of the cylinder shell of a twelve-line watch is only about five one-thousandths

as six degrees, as we show the lip m in Fig. 132, two degrees are lost in rounding. The space k f on the egress or exit side is intended to be about f

f our escape-wheel tooth must part with the exit lip of the cylinder. From e as a center and through the point s we draw the line e l''. With our dividers set to the radius of any convenient arc which we have divided into degrees, we sweep the short arc d'. The intersection of this arc with the line e l'' we name the point u; and from e as a center we draw the radial line e u f'. We place the letter f'' in connection with this line because it (the line) bears the same relations to the half shell of the cylinder shown in Fig. 133 that the line f does to the half shell

presents the position of the half shell of the cylinder when the tooth rests against it on the outside. If we should make a drawing of an escape-wheel tooth shaped exactly as the one shown at Fig. 132 and the point of the tooth resting at x, we woul

SCAPE-WHEEL TOOT

oth into the cylinder. To do this is simple enough: We first produce the arcs a b c, Fig. 133, as directed, and then proceed to delineate a tooth as in previous instances. To delineate our cylinder in the position we have assumed above, we take

ter of the cylinder shell. Consequently, if with this space in our dividers we set the leg at d, we establish on the arc b the point i. We locate the center of our cylinder when one-half of an entering tooth has passed into the cylinder. If now from the new center with our dividers set at four of the spaces into which we have divided the line e f we can sweep a circle representing the inner surface of the cylinder shell, and by setting our dividers t

line on the opposite side of the point g, as shown at g k', and we thus bisect the cylinder shell into two equal parts of 180 degrees each. As we previously explained, the entire extent of the cylinder half shell is 196 degrees. We now set our dividers to the radius of any convenient arc which we have divided into degrees, and from g as a center sweep the short arc l l, and from the intersection of this arc with the line

establish the point p; we halve this space and draw the short radial line p' s' and p s. From the point e on the arc A we lay off twenty-four degrees and establish the point t, which locates the heel of the next tooth in advance of A. At two and a half

tent of the banking slot of the cylinder, which is usually made to embrace an angular extent of 270 degr

s necessary with the pupil to institute a careful analysis of the actions involved. In writing on a subject of this kind it is extremely

much cut away, so the tooth on entering the half shell after parting with the entrance lip does not strike dead on the inside of the shell, but encounters the edge of the exit lip. In this case the impulse of the balance would cause the

knows to be a faulty escapement, as, for instance, a cylinder in which too much of the half shell is cut away; but in every instance let the tooth be of the correct form. Then delineate an escapement in which the cylinder is correct but the teeth faulty; also change the thickne

illed workman. The question is frequently asked, "How can I profitably employ myself in spare time?" It would seem that a watchmaker could do no better than to ca