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PREPARED BY
T H E GRUEN WATCHMAKING INSTITUTE
LITHO tN U.S A •. Copyright, 1948-The Gruen Walch Compony ,r ,, TABLE OF CONTENTS
' A BRIEF HISTORY OF THE WATCH ESCAPilY1ENT Part 1-What' is the Escapement? _____ I TOOLS Part 2-Delinitions of the Various Terms Used Part I-Acquiring Skill in the Use of Tools ...... I in Connection with the Detached Lever Part 2-Use of Saws ______2 Escapement ______I Part 3-Demonstration and Instruction in Sawing TRAIN and Filing ...... 4 Part 1-What is the "Train" of a Watch Move- Part 4-The' Lathe and Turning 4 ment? 1 Part 5-Hardening and Tempering Steel ...... 5 Part 2-Depthing ...... 5 Part 6-Drills and Taps ... 6 Part 3-Turning Pinions-----····················· 6 The Metric System 6 Characteristics for Reading Blue Prints ...... 8 WINDING AND SETTING Part 1-What is the Dial Train of a Movement? I TURNING Part 2-Making Various Winding and Setting Part 1-Turn and Finish Square Shoulder Pivots 1 Parts ...... 2 Part 2-Turn and Finish Cone Shoulder Pivots .... I Part 3-Fit Dial and Hands ...... 3 . Part 3-Turn Various Balance Staffs to Measure- CLEANING AND OILING ments ------2 Disassembly ______I Cleaning .... 7 BALANCE Assembling and Oiling ...... 7 Part I-What is the Balance Wheel? ____ I ADJUSTING Part 2-Staking the Balance Wheel to the Balance Staff ______I Part 1-What is Meant When We Say a Watch is "Adjusted" ______I Part 3-Truing Balance····------2 Part 2-Position Adjusting ______1 Part 4-Poising Balance _____ 3 Part 3-Temperature Adjustment ·············--- 2 Part 4-Isochronal Adjustment ············---- 2 HAIRSPRING Various Kinds of Time ·····------3 Part I-What is a Hairspring? ... ____ I Part 2-Level and Circle Hairspring _____ I MISCELLANEOUS REPAIR DATA Part 3-Collet and True Hairspring _____ I Polishing Balance Staff Pivots ______1 Part 4-The Overcoil or Breguet Hairspring ...... 2 Centering Staff in Balance Wheel ···········--- I Part 5-Level, Center and Circle Hairspring in Removing Broken Pallet Arbors _____ I Movement ------3 Tightening Loose Cannon Pinion _____ 1 Part 6--Manipulation of the Hairspring 3 Removing the Second Hand in Gruen Model Part ?-Vibrating Hairspring ···········---········ 5 # 400 Movement ____ I Part 8-Miscellaneous Hairspring Data ...... 5 Removing Upper Third Wheel From Sweep· Second Movements ______2 Removing BrOken Screws ______. ______2 JEWELING Removing a Broken Balance Wheel Screw ...... 2 Part I-What is the History of Jewels as used in Watchmaking? ______I What is Magnetism? ------~-- 2 Magnetized Tools and Watches ----······ 2 Part 2-Fitting of Train Jewels, Balance Jewels and Cap Jewels ______I Theory of Demagnetization ____ 2 Demagnetizing a Watch . ____ 2 Part 3-What is Friction Jeweling? _____ 2 Part 4-Bush and Upright Jewel Holes ---- 4 TROUBLE CHART Dial and Hands ---······------1 MAINSPRING Balance Assembly ...... 1 Part I-History of the Mainspring ___ I Escapement ____ 2 Part 2-Fitting and Selecting Proper Mainspring I Train ...... 2 Part 3-Miscellaneous Mainspring Data ...... 2 Mainspring Barrel Assembly ...... 2 A Few Mainspring Don'ts ______2 Winding and Setting Mechanisms 3 Ever since our primitive forefathers measured their time. However, the depsydra, too, had its limitations. daily tasks by the march of the sun across the sky, When the reservoir was full,. the water ran faster time-telling has held a vital place in everything than it did ':"hen it was neatly empty. As a result, great and small that man has done. by 250 B.C. the early clepsydra had given place to If you are carrying a watch in your pocket or on a water clock with a dial which was operated by a your wrist, place it before you so that you can better floating ratchet. understand the romance nnd wonder of its story. Hid There were many new improvements in the cen den within its platinum, gold, silver or stainless steel turies that followed. During the next fifteen hundred case is a tale as fascinating as the Arabian Nights. Sur~ years, the hour glass, the Roman lamp-clock and King rounding its delicate pinions, springs and wheels is Alfred's graduated candle came into l,eing. As life the whole history of astronomy - the story of man's quickened and the center of civilization shifted progress and invention. farther north, rhe mechanical clock was invented. Let us review this fascinating story. It begins count The early dock of about 1300 A.D. was a mechanism less centuries ago; with the men whom we call "cave of weights and wheels, capable of striking the hours. dwellcrs". As the sun moved, these men noticed that But even after it was well established, many people the shadows cast by the cliffs also moved. 1"hen they still dung to the old clepsydra,' just as many favored saw that the shadow of a tree fell in a certain place the manuscripts of the ancient monks long. after the invention of movable. printing type. on the ground, or on a stone. Soon they realized .I that one stone would mark only_ one point in the long In 1621 came the pendulum clock; in 1679 th, march of the shadow; therefore, why not use two experimental incline-plane dock; in 1826 the publi, stones ·- or even a number of them - to divide clock with illuminated dial - and finally, the modern the day into parts? Thus the ancients came to mark electric dock. time by shadows of objects that came between the For the early history of the watch we must go ground and the sun. back to the first half of the 16th century when clocks
We come down the ages, now1 to 4000 B.C. and were mQre beautiful than accurate, Peter Henleint a the very beginnings of recorded history - down to the young locksmith of Nuremberg, attacked the prob magiciun-priests of Bahylon and Chaldea. These wise lem of reducing the clock to portable dimensions. He men of old gave much of their time to the study of succeeded, thus giving to the world the first of the the heavens. It wns they who created the first calen· famous Nuremberg "eggs'', dar, who fit·st divided the year into months, days A short while later, during the time of Shakespeare and hours. and Queen Elizabeth, while watchmaking was develop As time passed and living became more complex, ing in Europe an
copy. The guild watches grew famous - noblemen the most important of these is The Gruen Watch from every European court cherished them as priceless Compari.y, to which we _now turn our attention. piec~s of craftsmanship. In 1874 the organization which is now known as . Wherl a guildsman finished a timepiece, he took it The Gruen Watch Company was founded by Dietrich to the master for examination. If it failed to pass the Gruen, Gruen;s purpose was to improve the pocket master's scrutiny, it was returned to the maker with watch. In the eighties he realized that ambition, pro a rebuke and perhaps even a line. So proud were these ducing what is now known as the 16-size pocket Swiss Watchmakers of their craft and their guild that watch. For many years this was the popular size man's they sigrled their watches as Raphael signed his paint· watch, and today is still the size made by all watch ings or Cellini his golden vases. factories for railroad use, It was a Swiss who invented the fusee, another Swiss The 16,size, however, did not materially reduce who introduced jewels for the reduction of friction the thickness of the watch. In 1902 Frederick G, and yet another who lirst invented the stem wind. It Gruen, Dietrich Gruen's son, evolved the Veri•Thin was also a Swiss who eliminated the solid upper plate wheel train. It was this idea, in conjunction with which covered the works and substituted the modern other modern improvements, that lirst made possible system of bridges. an accurate, thin pocket watch. Although the English led the world in the manu The Gruen Veri-thin, improved through the years, facture and sale of watches up to 1840, the Swiss fs recognized today as America's first accurate thin watch. Through a simple arrangement of the wheels, gradually drew ahead until they practically gained control of the world's market for watches. Thus it half the n10vement space was saved without reducing was that the little country of Switzedaod came to be the size or strength of the watch parts. Today's Veri famed for its watches and the name "SWISS" came to Thin watches are wafer-thin, streamlined, beautifully staod as the symbol of a line watch movement, designed versions of the original model. In addition to the 16,size watch and the Veri-Thin, The year 1848 marked tbe beginning of American Gruen has originated many other watchmaking 11firsts". watchmaking as an industry. The meeting of a young It was Gruen who lirst commercially pioneered the clockmaker and a young watchmaker brought to lady's wrist watch in America and more recently the gether two men who believed that watches could be oblong Cartouche (lady's wrisdet) and Quadron made by machinery. They found a man to finance ( man's wrist watch), rectangular movements which their venture and in 1850 established a small factory in permit greater size and strength of wrist watch parts. Roxbu1•y, Massachusetts. It was_ also Gruen who invented the tiny, gracefully There were serious problems ahead of the young slender Gruen Baguette movement. watchmakers. The old guild method of watchmaking Gruen's latest achievement is the exclusive Curvex used a model which had been fashioned by a master movement, which is patent protected against imita.M as a pattern and then distributed its parts among a tions until 1959, The Curvex movement, as its name great many skilled workmen-experts in forry or implies, is actually curved to fit the wrist~form case. fifty trades. Each man copied the model part which Its parts are devertheless rugged and full size, assur he had before him and returned the finished parts ing long life and precision accuracy. to an assembler who put them together. Among recognized, reputable watch manufacturers, The young watchmakers' idea, however, was to The Gruen Watch Company holds the unique position lay out the entire design of the watch on paper of being the only international watch manufacturing and make each part by machinery. The machine, of organjzation with factories on both sides of the course, would duplicate a part repeatedly, with little Atlantic, In picturesque Madre-Biel, Switzerland, or no variation. where men talk, think and live watches, the Gruen That, at least, was the theory. In actual practice it movenients are rnade, In quaint workshops suggestive was quite different. To begin with, there were 110 of the guild halls of old, these men who were trained n1achines of the desired precision. So before these in the watchmaking knowledge and traditions of men could make a single watch, they had to invent the ages produce movements of accuracy, compact .. the machines, build and install them. And, just as ness and durability. they were beginning to attain real success in their Upon completion, these Gruen movements are work, the panic of 1857 drove them into bankruptcy. shipped to the American case factory and service However, a short while later the company was re· workshops at Time Hill in Cincinnati. Here they are financed and today is still in operation, fitted into cases which American craftsmen design Since this first company was founded in 1850, other and execute. The linisbed timepieces are the famed watchmaking organizations have sprung up, building Gruen Precision Watches, known throughout the a strong and powerful industry in America. One of world as "America's Choice Since 1874''. PART 1-TURN AND FINISH SQUARE SHOULDER controlled by observing the blackening of the lap PIVOTS surface. Two each ,30, ,24, .18, ,14 and ,12 mm, tliamete1', h. Clean the pivot with a piece of pith dipped in benzine. a. Tighten the rod sec11rely in the lathe so that it runs true, i, Polish the pivot with the bellmetal lap charged with diamantine. The diamantine and oil are to be b. Properly sharpen the square graver. (See Tools, mixed until a thick paste is made, kneading long and P11rt 4 for tttrnhig anti sharpening the graver,) hard enough so there are no lumps. Apply the lap, c. Face off the end of the rod. (See A, figure 1,) as before, moving it carefully back and forth and d. Turn a straight shoulder pivot the length nf watch for the high-polishing black coating. The lathe which is three times the diameter of the pivot. Turn turns at a faster speed for polishing than it does for the pivot almost· to size but allow .05 mm. for grinding grinding. and polishing. (See B, figure 1,) The pivot must be cylindrical and not tapered. PART 2-TURN AND FINISH CONE SHOULDER e. In order to assure a clean, square shoulder after PIVOTS facing, make a fine cut with a diamond-shaped graver Two each .15, .14, .13, .11 anti .10 mm, diameter. in the corner where the shoulder and the pivot meet, First follow the instructions of Part 1, a, b, c and (See B, figure 1,) After grinding and polishing, the d and complete with the following: vertical and horizontal faces should meet at the bottom a. Tl\fn a cone shoulder pivot, the length of which of this cut, is twice the diameter, Turn the cylindrical part of the f. Bevel the end of the pivot and the shoulder at pivot almost to size, Then the cone portion of the a 45 ° angle. (See C, figure 1.) pivot is cut with the round-point graver, turning the g. Grind the pivot with the iron lap. Mix a small cone down to meet the cylindrical portion. (See A, quantity of oilstone powder and watch oil with a figure 2.) The finished cone should describe an arc of knife on the polishing block until a thin paste is a circle. (See B, figure 2,) produced, Spread a thin film of this paste on the b. Grind the pivot with the iron lap. The rounded lap and place the lap under the pivot. Run the lathe corner of the lap is placed againit the cone. Then at medium speed. The form of the pivot can he
A
~ ~EVEL
Figure I-Turning and Finishing Figure 2-Turnlng and Fl11l1hlng Square Shoulder Pivots Cone S/tou/der Pivots 2 Turning
use the oilstone paste and grind in the same manner I. Cut off the staff. as for a square shoulder pivot. m. Chuck the staff by the hairspring collet shoul c. Clean the pivot with a piece of pith dipped in der, _watching to see that it runs true. benzine. n. Turn the lower end of the staff, measuring d. Polish the pivot with the bellmetal lap as in from the end up to the roller seat and ·bring to the (i) Part I. correct length. Turn the roller table shoulder to. size, e. Complete the pivots by flattening the ends with allowing a slight taper. a hard Arkansas slip. Polish and finish with a hardened o. Turn the pivot to correct size. steel burnisher, rounding the corner of the pivots · p. Grind and polish the lower pivot, slightly. PART 3-TURN VARIOUS BALANCE STAFFS TO MEASUREMENTS a. Select a piece of steel rod of the proper diameter, \ b ..Tighten the rod securely in the lathe with· a A sufficient length of it extending from the face of lhe chuck to include the full length of the staff plus an 11dditional 2 or 3 millimeters. c, Sharpen the square, the diamond-shaped and the round-point gravers. The square graver is used for I r most of the turning, the diamond-shaped graver for B undercutting and the round-point graver for turning the cone on the pivots. d. Face off the end of the rod. e, Measure from the end of the rod and mark for -~--- n • - the balance seat. Turn the shoulder on which the C balance is to fit, allowing .05 mm. for finishing. Face the balance seat. (See A, figure 3,) f. Measure from the end of the rod and turn a mark for the hairspring collet seat. Turn this seat, (See B, figure 3,) g. Turn the conical pivot to correct size, (See C, figure 3.) h. With a diamond-shaped graver make the under cut on the face of the balance shoulder for rivetin_g. (See D, figure 3,) i. Turn the oil groove between the pivot and the hairspring collet shoulder and bevel this shoulder. (See E, figure 3.) j. Rough out the lower portion for the roller shoulder. Make this long enough to include the lower +crt -at+- pivot and thick enough for strength while grinding £ SLIGHT BEVEL and polishing the portions so far turned, k. Complete the shoulders on the upper end of the staff to exact size and grind and polish the pivots. Figure 3-furnlng llalance Staff PART I-WHAT IS THE BALANCE WHEEL? proximately twice the number of holes as the final The balaQ~.is !'1,~_g<>':'!'f"ittg. part . "!. r~gulat<>r.of. number of screws used. a. ~h. Jt was first used in 1600 and was merely When the watch is exposed to high temperatures ·a crude wheel made of any kind of material. This the rim will have a tendency to expand and make the proved inadequate as the accuracy of a watch depends watch run slow. However, as the brass on the outer upon the balance. If its size and weight are not in rim expands more than the steel, the free ends of the correct proportion to the motive force and the rest rim curve inward and bring the weight toward the of the movement, no adjustments can be made to center of the balance. The opposite takes place when accurately maintain time. Variations encountered due a watch is exposed to low temperatures. The brass to the expansion and contraction of materials in the contracting ffiol'e than the steel tends to straighten balance wheel further hindered the operation of out the rim and carry its weight outward. The watch the watch and led to the discovery of the cut-rim will lose in heat if the balance screws are too near bimetallic balance wheel. the attached end of the rim. The watch will lose in The cut-rim bimetallic balance is made of a steel cold if the screws are too near the free end of the center bar or arm carrying a circular rim cut close .rim. The size of the balance is governed by the to the arm at two points diametrically opposite. distance between the center' of its weight and its axis. One free end of each section is attached to the Therefore, the object of compensation is to maintain c~nter bar. that distance. at its proper point in all temperatures. To eliminate the effects of the variations in tem To eliminate the variations caused by temperature perature the rim is constructed of brass and steel changes all Gruen watches are now equipped with a fused together. Brass, being affected most by tempera solid rim monometallic balance wheel made from a tures, is placed on the outer side of the rim. The new material manufactured under the Gruen trade· relative dilation between brass and steel is 18 to I 1. marked name Conoruma and is an alloy of nickel, Holes are drilled and' tapped radially around the rim steel, chromium, manganese, tungsten and carbon. for the balance screws. These screws provide the neces This new material is non-magnetic and practically sary weight to the rim and may be moved to new unaffected by temperature changes, therefore, re locations if necessary. For this reason, there are ap- quiring no compensation in the balance for heat and cold. (See figure 1,)
. ' ' :cur-RIM' PART 2-STAKING THE BALANCE WHEEL TO 1_BJME.TALLIC IIALANCE .WHEEL' THE BALANCE STAFF a. To remove the roller the balance staff is held by the collet shoulder in a pin vise. After inserting the roller in a wire chuck, it is removed gradually by turning the lathe pulley with the left hand while the pin vise, holding the balance staff, is kept steady in the right hand. b. To remove the old staff from the balance wheel, the staff is chucked by the hairspring collet shoulder. Turning the lathe at slow speed, carefully cut away the hub for the balance seat until the graver reaches the point where the balance seat and shoulder meet.
SOLID RIM At this moment a little ring drops off. The balance M,ONOMETALLTC'SALANCE WHEEL wheel may be lifted off now with the fingers, (See figure 2,) Figure 1-Balance Wheel c, To rivet the balance wheel on the staff, select Balance 3
Figure 6-Trulng Balance In Raund
and check that the height of the arms are equal. If If a balance is heavily out of poise, weight should they are not, raise or lower the arms so that they be added as well as subtracted. Adding weight is ac are in a common plane. Next check the rims between complished with the use of timing washers. The the arms. If they are not level with the arms, twist the thickness of the washer determines the weight. The arms until the rims are level. All truing should be timing washer used must be of the same diameter done with the fingers. The use of tweezers or metal as the screw or slightly smaller. A timing washer that wrenches may mar the balance. protrudes over the rim of the balance might touch the center wheel or pallet bridge and cause the PART 4-POlSlNG BALANCE watch to stop. A timing- washer too thick or more Screws are placed in the balance rim to assist in than one washer on a screw might cause the screw to close timing of a watch. The number of holes exceeds scrape against some part of the movement. The amount the number of screws in the cut-rim bimetallic balance of weight to be added or subtracted is left to the judg ro allow for moving of the screws in final tempera ment and experience of the watchmaker. It must ture adjustments. Due to elimination of the tempera not be done indiscriminately; to do so will upset the ture error in the new solid balance, it is not necessary regulation of the watch. to have additional holes. The screws are spaced to obtain equal weight. The weight and size of the The meantime screws are the friction-fit long thread balance in relation to the strength of the hairspring screws, usually of a heavier metal. Weight should never _must never be disturbed, Solid and cut balances are be added or subtracted to these screws. Should the poised in the same manner. heavy spot settle at a meantime screw, notice if the To test the balance for poise first clean the jaws opposite screw is at an equal distance from the rim as the heavy screw. If the heavy screw extends farther, of the poising tool and the staff pivots with pith. I.eve! the poising tool and adjust the jaws. Place it may be turned in to equalize the opposite screw the balance on the poising tool so that the cylindrical or the light screw may be turned out. Should both screws be equal, they 'should not be touched. The portion,of the pivots rests on the jaws. (See figure 7,) alteration should then be made by subtracting or The pivots should be round and straight; if they are adding weight from one screw on_,, each side of the otherwise, the balance will rock on this spot. A slight tapping of the poising tool with the tweezers will heavy or light meantime screw, as the conditions aid the balance in finding its heaviest point. warr~nt. The balance should be of equal weight throughout The balance should be moved approximately one all 36o" of the circle. If the balance is out of poise, eighth of a turn; if it is in position, move it ·an addi it will start to rotate. When the balance comes to tional eighth, etc., until the complete circle has been rest, the screw that is heaviest will be the lowest point tested, on the balance rim. To subtract weight, use the balance rest or scaffold made for this purpose. The balance rim rests on the two pins and the thread is straddled by them. Remove the heavy screw with a screw driver. Place the screw in the lathe and either undercu·t the screw head slightly or turn a slight bevel next to the rim. When 1screws have heads of large diameter, the balance screw under cutters may be used. To use the undercutters select one whkh has a smaller outer diameter than the bal ance screw, The screw threads should fit the hole in the undercutter closely, but not tightly, Rest the screw on the undercutter, Place the screw driver into the screw slot and turn with a slight downward pres sure. This will undercut the screw head slightly, Never shorten the length of the screw head by filing. Figure 7-Poising Balance PART I-WHAT IS THE HISTORY OF JEWELS AS to a mm1mum, The length of the hole should be USED IN WATCHMAKING? about equal to its diameter. The mean tolerance of Before the invention of the watch jewel the wheel the hole is about 0.005 mm., or about 10 times pivots simply ran in the holes of the brass plates smaller than a human hair, so close inspections and of the movement. In 1704 the art of piercing jewels measuring devices are necessary. The surface through for use in watches was invented by Nicholas Facio, which the balance pivot extends is rounded or curved a Swiss watchmaker, who was living at that time in so that when the cap jewel .is attached the oil is London. As can be understood, the introduction of held in place properly (see explanation of this pro jewels greatly increased _ the accuracy of watches. cess under the oiling method of the cleaning lesson). OF WHAT ARE JEWELS MADE?-Jewels for WHAT ARE THE VARIOUS KINDS AND USES watch movements are made of garnet, natural or OF WATCH JEWELS? scientific ruby, natural or scientific sapphire and a. Balance hole jewel which is drilled and finished sometimes of diamond. Garnet is the softest stone (as described previously), and in which the balance and is not used in high grade movements as it is staff pivots turn. (The balance wheel turns 157,680,000 subject to greater wear and breakage. times a year, so it is important to have a perfect hole WHAT TYPE IS USED NOW AND WHAT IS and cap jewels.) ITS CONSTRUCTION?-Most of the jewels used b. Train hole jewel which is drilled and finished today are of the scientific, or sometimes called syn (as described previously), and in which the train wheel thetic, ruby variety. This scientifically made jewel is pivots turn. produced of the same chemical elements as the natural c. Pallet fork stone which engages alternately with ruby, that is, aluminum oxide (Al, 0,) to which is the teeth of the escape wheel transforming rotary added some chromium oxide to give it the reddish motion to vibratory motion. color of the ruby. This powder or alumine is fused d. Roller table jewel which engages in the slot of or melted in a special oxhydric furnace at an extremely the pallet fork. There are several shapes of roller high temperature into big droplets called "boules", jewels-triangular, round, square, oval and the half which are appro'!'imately 1½ inches in length and moon, which is in use today, ½ inch in diameter. e. Cap jewel 01· endstone which has a flat surface These "boules" are then cut into slabs of various against which the end of a pivot revolves. The cap thickness by mean_s of a very thin bronze disc revolv~ jewel should be larger in diameter than the hole ing at very high speeds and charge
•
B Figure 6-Finishlng Setting' metal bushing, held in place on plate and bridges by screws is shown in B. Another type of "friction Figure 8-lncorrectly Set Jewels tight" jewel is set ih. a metal bushing and this bushing also held tight in the plate and bridges The friction-type jewel removes these irregularities as shown in C. The newest type of jewel, which is and makes complete interchangeability possible. very large, and is the same size of the metal setting and jewel combined of the types described previously By using new machines and dies of great precision is D. The following is a detailed discussion on this modern techniques accomplish: new type of jewel: Jewels that are exact as to diameter which The system of the "friction-type" jewel was used can be centered in the hole within one-half for the first time in 1920 by a Swiss manufacturer and hundredth of a millimeter. now, many years later, it has revolutionized the Strictly rectified jewel holes in the plate watchmaking technique. So promising as this process and bridges. was in the beginning, there still were certain difficulties that had to be overcome. The jewel manufacturers In addition, a special tool A and B, (figure 9) presses were not in position to guarantee a jewel of exact the jewels in uniformly and at always the same height. and regular diameter that would be absolutely con This tool presses the jewel to the desired height with centric to the hole. Thanks to the considerable prog a variation of 1 to l¼ hundredths of a millimeter. ress in jewel manufacture, this manufacturing process The difference in the thickness of the bridges no can be carried out quite generally. longer is of any consequence. However, only mathematical precision, perfect tools Another advantage of these large friction-type · and quality can meet the requirements of good manu jewels ( which are the same size as the bushings of facturing. In comparing the method of setting (bur the former type), is that they contain larger cup nishing) the jewels with that of pressing them in, space for retaining more oil over a longer period the following observations can be made: of time, D, (figure 7). The burnished-in setting, according to the method An important and often disputed question is that used, had two great technical disadvantages: of the firmness of the jewel in its place, Very thorough experiments with a dynamometer have shown an Setting jewels, which were not perfectly excellent resistance to pressure by the friction-type round or true in diameter, in holes that were jewel. When it is pressed in, it must resist the lateral too large1 unfortunately resulted in noticeable and perpendicular tensions and, therefore, it is made differences in the distances of the centers. A, more carefully and out of better quality ruby than (figure 8) shows plate hole too large, resulting in an off-centered jewel. On the other hand, setting jewels of un equal thickness in holes more or less deep resulted in considerable irregularities in the endshake. B, (figure 8) shows jewels of irreg ular thickness and causing variation in height.
f 11 ~1,'I C~J C D
Figure 7-0lfferenf Types of Jewels Figure 9-Tool Pressing Jewel info· Position PART I-HISTORY OF THE MAINSPRING the thickness desired for mainsprings. Throughout The motive power of a watch depends upon the the last process the steel is annealed many times to mainspring, which is coiled in a circular metal box prevent extreme brittleness and oxidation. Finally, or barrel. (See figure J.) The barrel has a cover, the ste.el is cut into strips which must be hardened the barrel cap, and both are mounted on the barrel properly in special hardening furnaces. At this point arbor. The inner end of th~ mainspring is attached the strips are thoroughly polished and then are cut to this arbor while the outer end fits against the rim into the proper width and length by means of very of the barrel. The majority of watches wind the accurate dies and fixtures. The springs are then put mainspring by turning the arbor, while in some, the into an oil tempering bath, after which the ends of barrel is turned to wind the mainspring. the springs are partly annealed and re-polished and given another heat treating process to assure the The mainspring for the first portable watch was proper molecular arrangement in the steel. Finally, hammered out of a band of iron by Peter Henlein of the tongue ends are riveted, the Springs are oiled and Nuremberg in 1504. The first steel mainspring was are ready for packaging. made about 1550. Since then the steel used in main springs has been improved by various methods. The During the winding of a mainspring there are mainspring used in high grade watches today is several forces at work: made of the finest steel possible. The following is 1. As the mainspring is being stretched during a brief description of the manufacturing process of winding its elasticity becomes greater. a mainspring: J 2. The mainspring is being bent. around the ar There are several characteristics that the steel should bor which causes the molecules on the inside to be possess: (1) be homogeneous, (2) have proper harden depressed while those on the outside are stretched. ing qualities, (3) stand a high degree of temperature 3. The mainspring is exerting a pressure or fric and (4) receive a good finish and clear color. tion against itself and is constantly sliding against The I basic material is the highest quality pure this pressure. Swedish ,iron ore. Processing it in a blast furnace 4. During the winding and unwinding of the produces pig iron of the highest degree of purity and mainspring there is a continual change of the bending uniformity. (Sulphur and phosphorous in the ore point from one· end of it to the other. act as strength sappers, while manganese and carbon silicon are strength givers.) The pig iron is melted PART 2-FITTING AND SELECTING into ingots in open hearth furnaces or in special high PROPER MAINSPRINGS frequency electric furnaces. The steel ingots are next Before fitting or replacing a mainspring it is hot-rolled into bars and sheets about 1/16 inch thick. necessary to be sure that the barrel is clean, true In the cold rolling process, the steel is reduced to and free on the arbor, To test the barrel, assemble it without the mainspring with the arbor held in a pin vise. Spin the barrel on the arbor. After the barrel is true and free and any needed corrections have been made, mark the outside rim of the barrel where the opening in the cover lies. When reassembling with the malnspring, it is important that the cover be re placed in_ the same position. Wipe off the mainspring with a piece of tissue paper dipped in oil and work it around the coils. Never straighten the mainspring. Wind the mainspring into the barrel with a main spring winder. Use the proper size hook. The barrel is divided into 3 parts: 1/3 is for the Figure I-Mainspring in Barrel arbor, ½ of the remaining area is taken by the PART I-WHAT IS THE "TRAIN" OF A impulses). This sum is divided by multiplying the WATCH MOVEMENT? total of the number of leaves in the third pinion, The maiq train of a watch movement, known as in the fourth pinion and in the escape pinion. An a compound train, consists of a series of wheels and illustration is: pinions for transmitting the power from the main~ 80 X 75 X 80 X 15 X 2 = 14,400,000 = 18 000 spring barrel to the balance wheel. (See figure 1 ,) 10 x IO x 8 800 ' As the, wound~up mainspring unwinds from the It must he understood that all 18,000 trains do not barfel arbor, the power is transmitted from the have the same number of teeth in the wheels and barrel, sometimes called the main wheel, to the leaves in the pinions. The size and constructi.on of the center pinion, to which is attached the center wheel. movement determine this number as larger move The center Wheel transmits the power to the third ments usually have more wheel teeth than smaller pinion carrying the third Wheel,which in turn engages movements. in the fourth pinion carrying the fourth wheel, which The 18,000_.train is known as the standard train transmits the power to the escape pinion carrying the and is used in pra~tically all movements today. For escape wheel. Up to this point the power has been of merly, there, were 1llany "fast:" trains such as 19,333 a rotary nature, in that the wheels are rotating, each - 19,440 - 20,160 - 20,222 and 20,940 vibrations wheel revolving more rapidly and in a different direc~ which were used in very small watches. The fast tion than the preceding one and with the power trains were employed so that the balance wheel was diminishing correspondingly. given a faster motion, thereby lessening to a certain extent the influence of outside disturbances such as The inclined surfaces of the impulse face of the quick jerking motions of the ann while the watch escape wheel teeth now transmit the power to the was worn. However, now wiih che many technical impulse face of the pallet stones, which transmit advances made in watchmaking, such as friction-type the impulses through action of the pallet fork to. jeweling, improved gear-cutting technique, modern the roller jewel, which gives the final vihratory motion inachines and equipment rhe present-day movements of the balance wheel. This shows that what is lost can be made with the standard train of 18,000 vi in the original power of the mainspring is gained brations. in the speed of the halance wheel, which indicates that a maximum of efficiency is obtained on a mini Defective gearing of the train (due to faulty design mum of power. or improper replacement of parts) can cause a movew ment to rlm erratically_ or to stop, due to a number WHAT IS MEANT BY THE TERM "AN 18,000 of causes. The most common are depthing too deep TRAIN"? or too shallow, pinions too large or too small, badly This indicates that the balance wheel will make worn teeth and pinions or incorrect endshake of 18,000 vibrations in one hour. If it vibrates more the pivots. Therefore, a careful checkup of the than for an 18,000 train, the movement will gain train is most essential in order to assure proper time~ in time and if Jess, it will lose. A train of this con keeping accuracy. struction will require the fourth wheel to make a DEFINITIONS OF THE TECHNICAL TERMS complete revolution in one minute ·and, as five vi USED IN WATCH TRAINS. (See figure 2.) brations of the balance wheel are made each second, WHEEL-Any circular piece of 'metal, usually the second dial will be evenly divided into 60 spaces brass, on the periphery of which teeth may he cut of indicating the seconds. various forms and numbers. These teeth mesh into To determine the number of vibrations a balance the spaces of the pinions. wheel wiU make h is necessary to· multiply the PINION-A smaller wheel of steel with teeth or number of teeth in the center wheel by the number leaves playing in connection with a larger wheel. in the third wheel, by the number in the fourth The projections on the surface of the pinion are wheel, by the number in the escape wheel times 2 called leaves and work into the spaces between the (because each tooth of the escape wheel gives two teeth of the wheel. Train 1
PITCH CIRCLll---A circle wnccntric wirh the dr cumference of a toothed wheel and cutting its teeth at such a distance from their points as to touch the corresponding circle of the pinion and having with that circle a common velocity, as in a rolling contact. PITCH DIAMETER-The diameter of the pitch circle, FULL DIAMETER-The diameter measured from point to point of the teeth. DISTANCE OF CENTERS-The distance measured on a straight line from center to cente'r between the wheel and pinion. (It should be measured very ac curately as on this measurement depends the entire success of all calculations for train wheels.) LINE OF CENTERS-A line drawn from center to center of any wheel and pinion at which the two acting points should meet. Figure 2-Wheel and l'lnlon Parts DIAMETRICAL PITCH-The diameter of the pitch circle, divided into as many spaces as there are teeth ,on the wheel or leaves in the pinion. CIRCULAR PITCH-The pitch circle divided into as many spaces as there are teeth on the wheel or leaves in the pinion, ADDENDUM---The acting portion of the tooth, either on the wheel or pinion, outside of the pitch circle, (Sometimes called the working depth.) DEDENDUM-The non-acting or inside portion of the tooth, either on the wheel or pinion, from the bottom of the addendum to the base of the tooth. DRIVER-The wheel or the one that forces the other along. DRIVEN-The pinion or the one that is being forced. Figure 3-Testlng D,. 1,thlng LEAD-The tooth or leaf of the driver that is in direct contact with the leaf or tooth of the driven. PROPORTION OF WHEEL TO PINION--The proportion must be, as the number of teeth contained in the wheel and pinion, and size of each, is to the distance of centers, within which they are to run. NUMBER OF TURNS OF A PINION·--Divirle the number of teeth in the wheel by the number of leaves in the pinion. NUMBER OF TURNS OF LAST WHEEL TO THE FIRST-Multiply the teeth in all the wheels (meshing Figure 4-Depthlng Too Deep in the pi,nions) together and divide that product by the total of all the leaves of the pinions. The quotient will be the number of revolutions of the last wheel to the first. IF A WHEEL IS LOST, HOW IS THE CORRECT NUMBER OF TEETH AND LEAVES DETER MINED? 3rd WHEEL-First, count the number of teeth in the center wheel and the· leaves in the ,frh pinion. Evety 4th pinion in a movement having a second hand must make 60 revolutions to one of the center wheel, therefore, the number of teeth in the wheel and leaves in the pinion must be so calculated as to Figure 5-Depthlng Too Shallow \
Train
8 times as many teeth as the 4th pm1on has leaves. Changing "f" into any of the most used pinion numbers as 6, 7, 8, or 10, the following solutions are obtained 48, 56, 64 or 80. 678 To
PART 2-DEPTHING The train of a watch should be of accurate con struction, high finish and the depthing of the wheels and pinions should provide a uniform lead throughout. Due to lack of apparatus by which the depthing of the teeth can be seen, the watchmaker has to depend upon touch. Therefore, the train is one of the most difficult sections of a movement to control. Before inserting the wheels in the movement it is necessary to clean thoroughly aU jewel holes, pinions, wheels and pivots. Figure IO-l'lnlot1 with 6 l.e@vu \J? ith the bafance and fork removed, test each wheel by pre.ssing a painted pegwood against the pivot of the pinion into which the wheel engages. (See figure 3.) Lead the wheel slowly back and forth. If the 1-vheel cra.(ks or jumps, the depthing is too deep (figttre 4) or the pinion or whCel too large, if the wheel 9ljpt:, or slides, the depthing is too shallow, (figure 5) or the pinion or wheel too small or too far apart. If no defects were found, wind the main ::pr i0g and if the· train is frc.--e throughout, it will b.e observed rhat the moment the mainspring is com Figure 11-l"iomn ,",w Smcrll pletely unwound the escape wheel will turn in a contrary direction, The dcpthing tool, if one is available, can be used to St'e the action of chc gears. Care nnist be taken thn t the dis ta nee taken by the whetl.'l in the tool is tLe same aj in the movement, Adjust the points ef 1 he depthing tool perpendicular to the movement phae and exactly in the center of the pivot holes. 'VVithont ch,rn~ing the distance between the points, ph!ce the ·wheel and pinion together between the V ccorers an Figure 2-Circular Escapement 1, Guard pin shake 2, Jewel pin shake 3, Roller jewel 4. Fork slot 5, Impulse roller 6, Banking pin 7, Fork 8, Pallet arbor 9, Pallet 10. Pallet stone 11. Lock 12. Escape wheel 13. Escape pinion 14. Drop 15. Guard pin 16. Safety roller Figure 3-Compromise Escapement wlt/t Built-In Banking I Showing Receiving Action I Figure 4-Compromise Escapement wlt/t Old-Style Banking /Showing Receiving Action) Escapement 5 The action betwen the wheel and the pallets should be that the heel of the tooth glides along the impulse plane of the stone until finally the two impulse faces 6 meet nearly parallel. Then the heel of the tooth passes the let-off corner of the pallets. LOCK.-Lock (see figure 9) is the disi;!JlCe_itotQ ~ckil)g corne1c of,,a_]?~Het.stg.n~ to. tpeppin;a.t· 1 0 ~ ;1re '!;cit1H :I~Ra~~~k::;J~~ir;s;·~t·N;:t/~;·;~~ sihle··-consisten-t with allowances made to cover certain unavoidable mechanical errors such as sideshake in the pivot holes, inaccuracy of the escape wheel in \, round, variation in spacing of the teeth, etc. j The amount of locking in the pallets is very im portant for the good performance of a watch. If it is shallow, the teeth are liable to fall upon the im Figure 7-Checking Banking Action pulse face, a very serious defect, If the locking is too 1. Safety Roller 4, Banking deep, then too much power is required in unlocking 2. Roller jewel 5. Fork and the power used is taken from that required for 3, Guard pin 6. Roller impulse table the impulse to the balance. The amount of lock should guard pin does not get above or below the safety roller. Test by raising the fork to the highest position its endshake will allow. Care should be taken that the hollow for the passage of the guard pin is wide and deep enough so as to avoid contact with it when passing by. IMPULSE AND LIFT.-An escape tooth, in de livering impulse to the pallet, moves in an arc of a circle. The circular impulse is measured from the SLIDE center of the escape wheel and is divided between an escape · tooth and a pallet stone. Any alteration made in an escapement by moving a stone in or out changes the impulse action and may also change LOCK the extent of the arc of movemep.t of the pallets. This is known as ulift". The term 11lift" i~ ~p_plied .. to the_ thrust. given to tlie___paHets by an escape tooth. The lift is measured from-i'lie.palleTcenter and is also divided between an escape tooth and a pallet Figure 9-Lock and Slide stone. be from 1/8 to 1/5 the width of the impulse face of the pallet stones. Moving one pallet stone either outward or in 6 ward alters the lock on both stones. When a stone is drawn outward it cau~es the tooth to drop farther up on the locking face of the opposite stone. Moving it inward has the opposite effect. If one pallet stone is set out or toward the wheel or away from it, it will increase or decrease the locking on both stones just as much as either one is moved, If the locking is too light and one stone is set out, it might increase the locking slightly. If the watch was '"in line", it would be thrown out of line by moving only one stone. To keep the watch "in line", move each stone out one-half as much as is required to increase the lock. Figure 8-Checking Guard Pin Action Testing Lock.-Move the fork slowly from left to right. When the tooth drops, it should drop safely 1. Safety RolJer 4. Banking 2 •.Roller jewel 5. Fork on the locking face, not on the impulse plane. The 3. Guard pin 6. Roller impulse table latter would indicate a shallow depth. The watch PART 1-WHAT IS MEANT WHEN WE SAY A b. By rating is meant the rate of a movement is WATCH IS "ADJUSTED"? determined by the amount of time it gains or loses The term uadjusted 0 or "adjustment" represents per day. A perfect rate is one in which the gain or a near approach to mechanical perfection and the loss is exactly the same per day, Subsequently, a good ideal of timekeeping accuracy. rate is one in which the gain or loss is approximately A iood watch usually is said to have the following the same per day, A poor rating is indicated by a adjustments: position, temperature and isochronism. gain or loss that varies considerably from day to day, The rating of a movement varies with its size and a. Position Adjustment-A watch is so adjusted quality: a lady's movement has a greater variation when it has approximately the same rate in its various than a man's strap movement, which in turn has a positions, such as dial up, dial down, stem up, stem greater variation than a pocket watch movement. down, etc, c. By regulation is meant that a movement, after This adjustment is "built in" by having all the being cased, should be regulated to the individual parts fitted precisely so that there is a minimum of wearer, as each owner has different habits, such as friction to overcome excessive loss when the watch degree of activity, type of work, climatic conditions, is carried or worn in various positions. etc. Precision timekeeping is affected substantially b. Temperature Adjustment-A watch is so ad by these things, justed when it has approximately the same rate in both hot and cold as well as normal room temperatures. PART 2-POSITION ADJUSTING Adjusting of a watch really starts with the barrel. This adjustment is "built in" the movement by the Close position and isochronal rating cannot be attained use of Conoruma, which is an alloy of nickel, steel, unless the main train is in first-class condition. A chromium and .other metals. This produces a balance correct amount of endshake and sideshake is impor wheel and hairspring with "invariable elasticity", tant and all train wheels and balance pivots should creating no thermal error and requiring no com be well rounded and polished, pensation in heat or cold, Likewise it is non-magnetic. If a watch is not of the anti-magnetic type it c. Isochronal Adjustment-A watch is so adjusted should be tested for magnetism as it is useless to when it has approximately the same rate when it is attempt to adjust a watch if it is magnetized. The fully wound as when it has been running about hairspring must be flat, true on the collet, well 24 hours. centered, the overcoil correctly curved and the watch This adjustment is likewise "built in" the movement 11 "in beat , by having the hairspring of a certain length and the The arc of motion of the balance wheel, when fully pinned ends of the coil of a certain shape, This wound, should be about 1 ½ turns or 540°, that is, results in having the balance wheel make· every vi it will move ¾ turn or 270° in one direction and bration, whether a long arc or a short arc, in the then return the same amount in the other direction. same length of time. The arms of the balance wheel become visible at WHAT ARE THE THREE CATEGORIES OF the moment it completes the arc of motion and starts WATCH ADJUSTING? in the opposite direction on its return vibration. The a. By timing is meant a movement is brought to balance arc should be examined in all positions and time after it has been overhauled and/or repaired. if the motion is faulty in certain ones, the necessary A movement may show a gain or loss timing rate corrections should be made before any adjustments for a number of reasons. The most frequent being: to position or .isochronism are attempted. by the fitting of a new hairspring, balance staff, The impulse communicated to the balance wheel, balance hole jewels or ma'inspring. Such errors can through the escapement, should take place at the be corrected in most instances by the manipulation moment when the hairspring is at its state of rest. of the hairspring and other parts or by moving the An impulse delivered before the point of rest will regulator or by the addition of proper timing washers. accelerate the vibrations and one delivered after will Adjusting 3 the length is concerned usually consists of about 13 VARIOUS KINDS OF TIME coils, The average person probably assumes that time, as On a flat hairspring the vibrations are wholly on we know it, is determined from the sun. The follow one side and opposite the regulator pins. A similar ing is a brief description of four different kinds of motion takes place opposite the inner terminal. These time of the observatory or the astronomer, to all of eccentric motions affect the isochronism because of which our standard time is very closely related. various conditions: the principal ones are a constant Solar Time is really time by the sun; and the solar oscillation of the center of gravity, a persistent push day is the interval between two successive transits ing and pulling· at the balance pivots and the effect of the sun across the same meridian. This interval of torsion which is a circular impulse that takes place may vary as much as 30 seconds plus or minus in at the innermost coils of the hairspring, The result 24 hours and no two consecutive solar days are exactly is a retardation or acceleration, depending on the the same in length. relative positions of the two eccentric motions as Sidereal Time is time as determined from the the balance wheel vibrates. The errors thus produced "fixed" stars, the nearest of which is about 25 trillion can be varied by altering the length of the hairspring. miles away, or nearly 300,000 times the distance to The rules governing this for a flat hairspring, are the sun. The revolution of the earth on its axis is as follows: the most uniform and constant motion known to science and the sidereal day, the basic time unit of our When the distance between the inner terminal and observatories, is the time taken by the earth to make the regulator pins stands at .whole coils, the arcs one complete revolution. Unlike the solar day, this gain, is a constant interval, its duration being equal to When the distance is whole coils, plus ½ coil, the 23 hours, 56 minutes, 4.09 seconds. short arcs lose. Mean Solar Time differs from solar time, and the When the distance stands at whole coils plus ¼ solar day is likewise an unequal interval. But time or ¾ of a coil, the short arcs· are more nearly iso pieces are designed on the basis of uniform mecha chronal. nical motion and therefore demand a convenient unit of unchanging value. The mean solar day is such The purpose of the overcoil is to avoid any side a unit. It is equal in duration to the mean or average bulging during the expansion and to center all the length of all the unequal solar days in the year and coils concentrically around the balance staff. Because is determined by the transits of an imaginary sun of the variation in the direction of the forces directed crossing the meridian at regular intervals. On only on the balance staff, as ~ result of the continual motion four days in the year do watch time and solar time of the inner pinning point at the collet, and its agree. relation to the outer pinning point at the stud, Standard Time is local mean time of any selected it is , a debatable question whether a theoretically meridian as, for instance, the meridian of Green correct form of overcoil has ever been developed. wich, England. Owing to the vastness of the North However, the following rules for altering the over American continent, our familiar time belts were coil may be used. To make the watch run fast in established in 1884, each approximately 15 degrees the short arcs, bend the overcoil in towards the balance in width, westward from Greenwich. (The Eastern staff. To make it run slow in the short arcs, bend it Zone is 75 degrees W, or 5 hours slower than Green away from. the staff. wich; the Central Zone is 90 degrees W, or 1 hour To alter or reshape the overcoil, the overcoil form slower than Eastern; the Mountain Zone is 105 degrees ing tweezers are used. Any alterations should be made W, or 1 hour slower than Central; and the Pacific gradually, for, in bending, the hairspring is liable Zone is 120 degrees W, or 1 hour slower than Moun to be weakened and possibly broken. tain Time,) One of the most important factors in repairing To remove the movement from the back, place the watches is the availability of the proper tools and tip of the knife. against the lower plate so it contacts equipment. Always make certain that your tools are a solid surface. (See figure 1.) arranged properly on the bench and in good working Preliminary Examination order. Use the correct tool to perform each specific After the movement is removed from the case, operation. Makeshift use of tools will result in Joss examine it to locate possible broken, worn or rusted of time and inaccurate workmanship. parts which should be replaced or repaired. Deter The use of genuine replacement parts facilitates mine at this time, if possible, what caused watch repair and insures maximum satisfaction of your failure and the amount of repair necessary to remedy future customers. it. The exploded views (figures 2 and 3) show all the As the steps of disassembly progress, carefully note parts of a Gruen Curvex movement in their relation the condition of each part as it is removed. At this ship to one another as they are separated from the time it may be determined which parts require repair movement. Each part is indexed and referenced to or replacement. Refer to the preceding lessons when the text. Where the same part is again shown on making repairs. another illustration, the index number is repeated. Removal of Hands Refer to the illustrations when performing any repair operations until you are fully familiar with the Extreme care must be taken when removing the hands to ensure that the dial face is not marred or various parts. scratched. Use a dial protector and a standard plunger The following cleaning and oiling instructions type hand removing· tool or two lever hand removers have been written around the Gruen Curvex move machined to fit under the hand hub when performing ment. However, these instructions can easily be made this operation. to fit any type of watch of any manufacture, Slide the dial protector under the hub of the hour DISASSEMBLY hand (21) as far as possible and place the hand re mover tool jaws under the hour hand hub. Press Removol from Cose down on the tool to release the hands from their Locate the opening lip on the back of the case. post. (See figu1'e 4,) Using a bench or case knife, insert the tip under the When the lever hand removers are used, place one opening lip and apply a slight leverage to open the on each side of the hour hand hub and press the case. The bezel should open easily without prying. levers down. (See figure 5,) Removal of the second hand (20) may be accom plished in the same manner. Ho'Yev~r, if it is not possible to do this, and especially if the hand is tight, loosen the dial and raise it with the bench knife. The pressure of the dial against the second hand will release it. Removal of Dial To remove the dial (19), loosen the dial screws (1) sufficiently to free the dial. It is not necessary to remove the screws. Insert the tip of the bench knife under the dial (19) at the position of the screws (1) and gently work the dial from the movement. Tighten the dial screws (1) back into position to prevent their Joss. Figure I-Taking Movement out of Case Some movements utilize a dial washer ( 16) under n ii' Figure 3- Q Exploded View Train Side ::, 27. Upper balance cap : Q jewel screw ::, 28. Upper balance cap Q. jewel 0 ::: 29. Regulator ;; 30. aµrspring stud screw CQ 31. Balance bridge screw 46 32. Balance bridge 33. Hairspring stud 34. Hairspring 35. Hairspring collet 36. Balance wheel 37. Balance wheel screw 38. Balance staff 39. Roller and roller jewel 40. Train bridge screw 41. Upper escape cap jewel screw 42. Upper escape cap jewel 53 43. Train bridge 44. Center wheel and ,4 pinion 45. Third wheel and pinion \, 46. Fourth wheel and ,& pinion 47. Escape wheel and pinion 48. Pallet bridge screw 49. Pallet bridge ) ' 50. Pallet fork - 51. Pallet stone 52. Pallet arbor 53. Detent screw ~~ 54. Mainspring barrel cap 55. Mainspring arbor 56. Mainspring ~ \\ 57. Mainspring barrel 58. Mainspring barrel \ 60 59 bridge 59. Crown wheel 6\ 60. Crown wheel cap 61. Crown wheel cap screw 62. Ratchet wheel )2 63. Ratchet wheel screw 64. Click spring 65. Click 66. Click screw "' Cleaning and O/llng 5 worn pivots on the balance staff (38), condition of the roller table and tightness of the roller jewel. If the balance wheel (36) requires repair, place it aside and continue disassembly of the movement. The 36 balance wheel (36) may be repaired while the other parts are being cleaned. 34 Pallet Bridge and Fork ISee figure 9,J Remove the screws ( 48) attaching the pallet bridge (49) to the lower plate (2) and insert the lifting tool in the machined recess on the underside of the pallet bridge (49). Gently work the pallet bridge (49) loose from the lower plate (2). If the bridge is tight, turn the movement over and pl.lsh on the steady pins. The bridge will be released without damage to the pallet arbor (52) pivots, Apply equal pressure to both pins. Figure 8-Balance Wheel and Hairspring Note The hairspring (34) normally will free itself from The number of screws ( 48) attaching the the regulator pins as the hairspring stud (33) is pushed pallet bridge ( 49) varies with the watch out of the balance bridge (32); however, if the regu model. Some models utilize two screws, lator pins are closely set and retain the hairspring (34), whereas others use just one screw. I use a sharp-pointed tool to spread the regulator pins Grasp the shank of the pallet fork (50) with tweezers and free the hairspring (34). and lift the fork from the movement, To remove the balance bridge (32), unscrew the balance bridge screw (31) and lift it out with a Stem and Crown tweezer. Insert the end of the bridge lifter in the Loosen the detent screw (53) sufficiently to release recess machined on the underside of the balance bridge the stem (5) and pull the stem from the movement. (32) and gently work the bridge free from the lower Note plate (2), If the stem is broken or rusted so that it Disassemble the balance bridge (32) by removing cannot be removed easily, further disassemble the two upper balance· cap jewel screws (27) located the movement until the upper and lower on the underside of the bridge, As the screws (27) are plates are separated and then remove the stem. removed, separate the regulator (29) and the upper balance cap jewel (28) from the balance bridge (32). Dial Train and Setting Mechanism (See figure 8.) ISee figure 10,) Grasp the rim of the balance wheel (36) with Remove the cannon pinion (14) by tightening a tweezers and. lift it up and out of the movement. Make pin vise over it and holding the movement in the certain the hairspring (34) does not become entangled left hand. Pull off the cannon pinion with a gradual with other parts of the movement as the balance wheel twisting motion. (36) is removed, 14. 13 7 3 4 Carefully inspect the balance wheel (36) for bent or 48 49 50 Figure 9-Pallet Bridge and Fork Figure JO-Cannon Pinion and Dial Train Cleaning and Oiling 7 Using tweezers, grasp the mainspring barrel arbor Take the parts out of the rinse one at a time and (55) and turn it slightly .in a clockwise direction to dry them thoroughly with Selvyt or linen cloth free free the arbor hook from the hole in the end of the from lint. mainspring (56), Lift out the mainspring barrel Peg all jewel holes and other bearings from both arbor (55), sides, ·Buff or rub the cap jewels with pegwood Hold the mainspring barrel (57) firmly in the left until they are clean. Clean all pivots with pith. hand and, using tweezers, grasp the mainspring (56) Lightly brush all parts with a soft brush to remove about one turn back from the hole in its end. Gently lint or pegwood shavings. Use the brush sparingly. start the mainspring out of the barrel. Once the Excessive brushing will get grit and dust back into spring is released, cover the barrel with the right the jewels and bearing holes, hand so that the mainspring does not forcibly fly With all parts-new and old-thoroughly cleaned, out and become distorted. inspect the pivots, pinions and wheels. Check that If the winding pinion (4) and clutch pinion (3) the pivots are polished, straight and clean and that were not removed previously, lift the":J- out at this the teeth, pinions and wheels are clean and not time. damaged, Unscrew the detent screw (53). The detent (10) Check the jewels for tightness, cracked or chipped will fall from the dial side of the movement, holes and cleanliness. Turn the lower plate dial side up in the movement rest. Unscrew the cap jewel attaching screws (23 ASSEMBLING AND OILING and 25) and lift off all the cap jewels (24 and 26), The movement is lubricated at the various stages Note of assembly. A movement whose parts have been perfectly cleaned and skillfully repaired must be The number and location of cap jewels varies lubricated properly to ensure maximum efficiency and with the watch model. trouble-free service. Inspect all parts thoroughly. Make the necessary The maxi~ of Husing the proper tool" to perform repairs as outlined in the preceding lessons. The a specific operation also is true of oiling. Always movement should be repaired completely before it use the correct type of oil and make certain it has is cleaned. not lost any of its lubricating qualities because -of CLEANING age or the presence of foreign matter. When cleaning the movement, it is common prac Watch oils are made from petroleum, mineral, tice for the repairman to use any well-known cleaning vegetahle such as seed or nut-animal, or fish oils. solution, If regular cleaning solutions are not avail The most widely used type is that made by pro able, a simple watch cleaning solution can be made cessing the fats from the jaws of a porpoise. Also, as follows: Mix together 1 ounce Oleic Acid and 2 several synthetic oils have been developed in recent ounces of Acetone. Then mix together 4 ounces 22% years, some of which are made from various basic chemically pure ammonia and 25 ounces of distilled chemicals through very high temperature and distilla water. Now mix the first solution with the second and tion treatments, or, in other words, it is a highly let stand overnight to "age", The above makes 1 complex molecular process. Such .' a lubricant will never evaporate, corrode, leave a gummy residue or quart or 32 ounces. have any of the other disadvantages characteristic All parts of the movement, except the dial and hands of regular type watch oils. are to be cleaned in the cleaning solution at this time. If any parts were defective and required replacement, The characteristics of a good watch oil are: clean the new parts with the rest of the movement. Chemical stability-that it retains its body or Wipe off the dial and hands with a soft brush or makeup and will not break down in a short time cloth, never place them in the cleaning solution. under normal or adverse conditions. Polish and clean the case thoroughly. Make certain Non-corros/.ve-that it should not affect chemically the crystal is cemented properly. the metal parts or jeweJS of a watch, or in itself be Place the watch parts in a small perforated con affected by these parts, so that it will decompose, tainer. Insert the balance assembly last, Dip the Spreading-that it has a maximum tendency to container into the cleaning ·solution, Leave the parts stay in one place and not spread from pivots and in the cleaning solution for a short time, dependefit jewels. upon the strength of the solution, and then place them in benzine and rinse thoroughly. Remove the balance Volatility-that it has a minimum evaporation assembly first. Rinse and dry it separately and place point at various teffiperatures. it in a covered container, Place the other parts in a· Friction-that it has a maximum friction reduc~ second rinse and brush each part carefully to remove ing property. Oil is used in jewel bearings to reduce any gummy substances. Immediately place the parts the friction of the moving parts and the heat caused in a third jaf of clean benzine for the final rinse. by this friction, \ Cleaning and Oiling 9 G:17nci:=J . fl Figure 16-Oiling Train Jewels IMPROPERLY OILED TOO MUCH Oil PROPERLY OILED Cover the index finger of the left hand with watch it in the movement. Tighten the detent screw (53) paper. Hold the bridge in position with this finger. firmly in position. Using tweezers, work the wheel pivots into their Position the clutch lever (9) and insert the clutch respective train bridge jewels. With the bridge still setting spring (8) so it bears against the clutch lever. held in position, insert the attaching screws (40) Position the clutch lever bridge ( 11) and attach and tighten. If the movement uses more than one with the screw (12). train bridge, attach the bridge over the escape wheel ' Note first. Some watches do not use a separate bridge . Test the train for freedom of movement and proper to attach the clutch lever. endshake. To properly test endshake, hol Cleaning and Oiling 11 If a second hand (20) is used, place it on its post the bezel without snapping hard and injuring the and gently press it into position. It must clear the balance assembly. dial .with a minimum of space and yet not interfere Set the watch and check that the hands clear the with the hour or minute hands. crystal in all positions. Wind the watch and listen Place the watch 'in the movement rest and set to it in various running positions to make certain the watch. Look into it from all sides as the hands the case does not bind against any part of the move are rotated. Make certain the hands have proper ment and cause it to fall off in motion or stop. clearance and follow the curvature of the dial. The Timing hour and minute hands must dear the second hand in After a general overhaul of a watch, it often is neces all its positions. sary to make minor corrections in the timing. Note The method of timing is largely dependent on All hands should have a minimum amount the type of watch; i.e., wrist watch or pocket watch. of clearance in respect to the dial and one The position tolerances in the timing operation will another to eliminate the possibility of rub vary with the quality of the watch. bing the crystal. The first operation is to bring the watch to close time. Wind the watch fully and set it with a time Casing the Movement piece of known accuracy. Run it dial up for 24 hours Clean the case and make certain it is lint and dust and note the rate of gain or loss. Small variations may free and perfectly dry. Check that the crystal is ce be compensated by moving the regulator. However, mented properly. if large errors exist, it may be necessary to make On wrist watches fit the movement into the case adjustments on the balance or hairspring. This pro back. Place the bezel on the watch at the balance cedure should be continued until the watch has been wheel end of the movement and snap the other brought to close time. end of the case back into the bezel. On more delicate To position test a watch, wind it fully and set watches, where there is a likelihood of breaking or it with an accurate timepiece. Run it for 24 hours bending the balance staff when the case is closed, in the dial up position and note the rate of gain or first put the bezel on at the end of the movement Joss. Repeat this in the dial down and pendant down where the balance wheel is located. Position the positions for most watches. Where more precise po case back against the movement and, instead of snap sition rates are desired, the watch should also be run ping it into position in the normal manner, press in the pendant right and left positions for 24 hours with both forefingers on top of the bezel and lift each. with the thumbs on the ends of the lugs to slowly To obtain close position rates, the movement should push the back into the bezel. be checked for proper alignment of the escapement This will permit the back to slide gently into and balance assembly. PART 1-WHAT IS A HAIRSPRING? PART 2-LEYEL AND CIRCLE HAIRSPRING A hairspring is a simple, delicate circular spring The diameter of the spring, the length of the whose object is to give a constant, regular, harmonic spring, the exact length of the .overc-,il and the action· to the balance wheel. It was first introduced points of attachment are factors that will not be by Huygens in Paris in 1674. About 1690 the hair• considered in this lesson. The work conducted here is spring was already in general use in a number of only to teach the trainee the proper use of his tools forms: and give an idea how the work is accomplished. The plain fiat, two flat superimposed, the cylindrical, The two most common forms of hairsprings are conical and spherical. The only survivals today are the the flat and the Breguet. The flat hairspring is the cylindrical, for use on chronometers, the Breguet and older and more simple form and is the one used in flat for watches. our first experiments. The coils of the hairspring are The elasticity, length, thickness, height, form, ter· the same distance apart on all sides and have a flat minal curves, manufacturing processes, quality of the spiral form. The spring will be bent in several places metal and hardening are all factors which have an and the object is to return the spring as nearly as influence on timing. In order to obtain the fine timing possible to its original form. results of a well-poised balance, the hairspring must be true and its center of gravity coi.ncide with the PART 3-CC:>LLET AND TRUE HAIRSPRING center of gravity of the balance wheel. This results Colleting is the attaching of the inner coil of the in having the balance wheel make every vibration, hairspring to the brass collar or collet that fits friction whether a long arc or short arc, in the same length of tight on the balance staff. The collet is pierced to re• time, thereby making the movements of the balance ceive the hairspring which is held fast by inserting wheel isochronal which will give the watch the a small bt·ass pin,' The first step is to break out same rate when it is fully wound as when it has several inner coils of the hairspring to allow space been running for 24 hours, for fitting the collet. This amount depends upon the The use of either the Breguet or flat hairspring size ,;,f the collet and the distance between the coils, is largely dependent on the type of watch. The hair· The distance from the edge of the collet to the first ·,spring µsed most frequently today is the Breguet which coil is one and one-half the space between any two is patterned after the Phillip's theory. Where eccentric coils. motions may be encountered, affecting isochronism, A practical method to ascertain this distance is years of research have brought forth a Breguet hair• to drnw two horizontal parallel lines, tangent to spring with a scientifically correct overcoil. As the the outside diameter of the collet and draw a line :overcoU la pinned in or near the center of the perpendicular to the parallel lines. Center the hair• spring, the calls open out evenly without side pressure spring between these lines, The innermost end of to .eliminate eccentric motion. the spring to meet the perpendicular line and where Regardless of the type of spring used, it must be the line crosses at X ( see figure 1) is the point where scientifically ha1·dened and tempered. The diameter the hairspring is to be cut. After the spring is In of the spring must be in corrct proportion to the serted in the collet, the inner coil w.ill have the diameter of the balance wheel. proper space, Most hairsprings are made from steel. To eliminate To attach the hairspring to the collet first form the eccentricities due to temperature changes, rust an.cl tongue, which is the portion of the hairspring that magnetism, many watches are now equipped with a enters the collet hole. The length of the tongue hairspring made from a new type of material. All should be as long as the collet hole plus the distance Gruen watches now have this type of hairspring to the first coil. (See figure 2,) The tongue is formed which is known by the trade-marked name Conoruma. by grasping the spring firmly-with the tweezer,.,ij!. \ Hairspring with the main body of the hairspring. (See fig11te 12.) To circle the overcoil use the special hairspring over coil forming tweezer for this purpose, The overcoil is to be bent to the forr,n of a straight line joined by two quarter circles, the first circle to start abou,t 3 ° past the second knee. (See figure 13.) PART S-LEVEL, CENTER AND CIRCLE HAIRSPRING IN MOVEMENT The actual form of an overcoil is to a certain extent governed by existing conditions. For example, the measurement from the center of the balance hole jewel to the space between the regulator pins is a Figure 6-Marklng Taper Pin Sl!e definite factor and the curve of the spring must be· made to comply with it. (See figure H.) The regu, lator pins are two little pins made of brass riveted parallel to each other in the regulator, The regulator is concentric with the balance jewel hole and the hairspring must be perfectly free between the· pins. Before us we have a lower plate, balance bridge, cap jewels and regulator. The work now to be per formed is to make the overcoil, formed in Part 4, conform to the conditions created by these parts. Figure 7-Pln and Spring in Collet After. reshaping the overcoil, the hairspring is attached to the stud. Lay the balance bridge on the bench with the regulator downwards, push the overcoil between the regulator pins, then draw the free end of the spring into the hairspring stud and fasten it with a · brass pin, Now look down through the collec If the center of the balance hole jewel is in the center of the collet hole and, if, after moving the regulator, from slow to fast, the hairspring remains stationary, it is centered •properly. (See figure 15.) lf not, it can figure 8-Cuftlng Taper Pin be determined where to circle the overcoil to center the hairspring. (See figure 16.) When the spring is centered properly on the bridge, it is leveled without being removed from the bridge. In forming the ovctcoil and any alterations that were made afterwards, care must be taken to keep the overcoil parallel at all points with the body of the hairspring. (See figu,·e 17.) The hairspring must also be level with the balance bridge and any alterations necessary here arc due to the pjnning operation and must be made as dose as posslble to the stud. After centering and leveling on the bridge, the hairspring is put on the balance srnff. This is done on the staking Figure 9-Tightening Pin in Co/lat tool, using the same hole and the flat punch that were used for staking the roller table. The balance wheel is put into the movement and any minor adjustments are made at this point. PART 6,-MANIPULATION OF THE HAIRSPRING It is necessary to have the points of the tweezers of equal length, parallel t6 each other, free from roughness and thin enough to enter between the coils before attempting any work on the hairspring. A finished hairspring must be perfectly flat and centered to develop equally when the spring is wound or counterwound. The regularor pins are to bci per pendicular and parallel to each other, -free of purrs Figure JO-Locating Point for Overcoll PART, )~VIIIRAYING HAIRSl"IUNG ··'8. Jo 6tdng • hairspring, the 6rst•procedute is to 'determine the number of vibrations of the balance I g. wheel per hour. (This calculation will be found under \ lf Sf- ( d) at the end of Part 7) . Select a hairspring that has approximately half the diameter of the balance wheel. There are many factors in selecting a hairspring of the proper strength that can only- be · gained by Figure 17-0vercoll Parallel to lfalnprlllfl experience. One method is to suspend the balance wheel and hairspring an inch or two above the number of teeth in the center wheel by the number bench. If the distance between the point where the of teedi in the third wheel. The total by the number spring is held by the tweezer and the run of the of teeth io the fourth wheel. The total by the number balance is one-half inch, the hairspring is of the of teeth in the escape w"eeL The grand total by approximate strength. The inner end of the hair two. Then multiply the number of third wheel pinion spring is fastened temporarily to the collet. leaves by the number of leaves in the fourth pinion, b. The hairspring is then tried on the hairspring times the number of leaves in the . escape pinion. vibrator. This vibrator has a master balance wheel Divide the total leaves into total teeth for the correct with · hairspring enclosed in a case. On the movable hairspring vibrations per hour. In all cases where there is a second hand, this may be greatly simplified, Then the number of vibrations per minute can be de termined quickly by dividing the number of teeth in the fourth wheel by the number of leaves in the escape pinion and multiplying this result by twice the number of teeth in the escape wheel. Example: 80 X 60 X 70 X 15 X 2 x x - 18,000 vibrations per hour 10 8 7 PART 8-MISCELLANIEOUS HAIRSPRING DATA WHAT IS MEANT BY AN ISOCHRONOUS HAIRSPRING? An isochronous hairspring is achieved by ha~ing the hairspring of a certain determined length and the pinned ends of the overcoil of a certain shape. This results in having the balance wheel make every vibration, whether a long arc or Figure 16-Circllng Overeoll to Center Hairspring short arc, in the same length of time. Therefore, arm are tweezers. The hairspring is held by the the watch has approximately the same rate when it tweezers and so placed that the balance wheel arm is fully wound as when it has been running about is parallel with the arm of the master balance wheel 24 hours, and by means of a lever, both arms are set in motion. A flat hairspring has several eccentric motions which The point that is gripped by the tweezers is moved have a tendency to affect the isochronism, namely: until the two balances vibrate at the same rate, This (I) a constant oscillation of the center of gravity; is the point that tits beween the regulator pins and ( 2) a persistent pushing and pulling effect of the another quarter coil is allowed for pinning in the balance pivots; and (3) the effect of torsion, which is stud. c. The correct pinning point, or point of attach ment, of the inner coil must be observed carefully for this is a means to obtain an equal regulation in the, various positions. It has been found that one position of pinning distinguishes itself as best for pre cision rating. To find the correct pinning point for a particular watch, draw an imaginary line parallel with the crown, through the center of the balance and also a line at right angles to that line, bisecting the center of the balance. The hairspring is to be pinned so that it develops on the last mentioned line. (See figure 18.) d. HOW TO DETERMINE THE NUMBER OF VIBRATIONS OF 'HAIRSPRINGS. ~"1tit>lr .the Figure 1J-Locatlng Correct l'ln11ln9 · Point Q s u Make stem to fit movement l 2 3 Study and set up escapements l 2 Study setting and winding l Cleaning and oiling l 2 3 4 5 6 7 8 9 10 11 12 Cleaning and fitting ready-made staff l Cleaning and turning staff to fit movement l 2 .gulating and adjusting 1 2 3 4 5 6 7 8 9 10 11 12 Clean movement, overcoil and vibrate hairspring l 0 s u Level and circle hairsprings Collet and true hairsprings 1 2 3 4 5 6 Overcoil hairsprings l 2 3 '.4 5 6 Stud hairsprings l 2 3 4 5 6 Level and center hairsprings in plates 1 2 .3 4 5 6 Clean plates 1 2 Polish pivots on Jacot lathe 1 2 3 I+ 5 6 Set bezel type jewels in plates 1 Turn setting and fit lower train l 2 Turn setting only 6 Turn setting and fit upper train jewel l 2 Turn sel;ting only 6 Make setting for balance jewel & fit in plate 1 Turn pinions 1 2 Bush and upright center hole 1 Bush and upright lower train 1 Study and fit mainspring 1 Study train depthings and endshakes 1 Make clutch lever to fit, movement 1 Make click spring to fit movement 1 Repi'lrot 1 0 s u Turn and finish square shoulder pivots - 2 each .30 .24 .18 ,14 V .12 Turn and finish cone pivots - 2 each ,15 ,14 .13 .11 .10 Turn three brass balance staffs to measurements - print #1 1 2 3 Turn three steel balance staffs to measurements - print #2 1 t,,/ 2 3 Turn three steel balance staffs to measurements - print #3 Turn three steel balance staffs to measurements - print #4 1 2 3 Alter balance staffs to fit plates, wheels, and rollers 1 2 3 4 5 6 Stake balance wheel to staff 1 2 3 4 5 6 True balances 1 2 3 4 .5 6 Poise balances 1 2 .3 4 5 6 \ The proper usage, care and maintenance of tools When filing, maintain perfect balance of both and equipment IS VERY IMPORTANT. Tools and hands. Keep the file in a level position at all times. other equipment should be kept as dose to their (See figure J ,) Filing is accomplished by the pressure original condition as possible by periodic recondition given the file on the forward stroke. The action of ing, cleaning, and where necessary, oiling to prevent a file in this respect is similar to the teeth of a saw. rusting. Since the cuts of a file are made on a slant, no cutting can be done on the return stroke, and no pressure is PART !-ACQUIRING SKILL IN THE USE OF applied. jl.fter the filing is completed, the surface TOOLS should be tested with a scale or straight edge to ascertain if the filed surface is perfectly flat. (See THE FILE-The shape of the file to be used is figure 2.) determined by the shape of the piece which is to be filed. The various shapes of files ordinarily used are DRAW FILING-Draw filing is drawing a fine known as flat, square, three-cornered, round, half cut file over a piece of work, always moving the file round and ratchet. in a right-angled direction to the length of the file. The force to move the file is applied principally by the fingers which hold the file right over the place to be cut rather than by the handle which is used chiefly to help guide the file. (See figure 3,) -- PIN FILING-For this the blank wire is secured in a pin vise, the extended portion of the wire rests in a groove in a hardwood block held in the bench vise, and the work usually rotated by the left hand while the file is operated by the right hand. (See figures 4 and 5,) To apply a high polish to certain taper pins, a burnisher is used in the same manner as the file, FILE HANDLES-Power and speed are sacrificed Figure I -Flat Filing in roughing out work without handles on large files. Finishing work with small files is also handicapped when handles are not used, Handles should be in proportion to the size of the files and must be fitted securely. To fit soft wood handles, a hole should be drilled, large enough to allow about half of the pointed end of the file to enter; then the handle driven on with a mallet until practically the entire end is imbedded in the handle. Hardwood handles should be drilled the same as for soft wood but the pointed end should be heated red hot and then allowed to burn its way into the handle far enough so that a final tap with a mallet will tighten it securely. CARE OF FILES-A new file should be used first on brass or other soft metal before using it on steel. The teeth on new files are extremely thin at their ends and may break off if used when new on hard metal. Using files first on a soft metal ensures that Figure 2-Checking Filed Surface the ends wear slightly. 2 3 4 5 6 7 a 9 lO 11 12 13 14 ~ l !t.. 21 20 19 .--18 17 16 15 figure 7-Jewefer's Lathe 1. Draw-in wheel 6. Front outside shield 11. Lever 16. Bed 2. Adjusting nut 7. Headstock spindle 12. Spindle 17. Bolt nut 3. Loose bearing 8. Slide 13. Tailstock 18. Base 4. Rear outside shield 9. T graver rest I 4. Spindle button 19. Headstock 5. Pulley 10. Post 15. Lever 20. Lever - 21. Index pin w Tools 5 the cutting end of which is usually made diamond shaped, In turning, the graver should be held to the part being turned so that the body of the tool lies nearly at a tangent to it. The different gravers 0 are shown in figure 10, The two forms most generally A used are the "square" A and "diamond" B. These, together with the right-angle point C and a rounded 0B point D will fulfill practically all types turning work. The grinding of gravers should be done with a flat stone, like India oilstone, hard Arkansas, etc, Spread enough oil on the stone to float the waste particles of s;eel so that they do not clog the grain of the stone. Hold the graver with fingers close to the stone, to keep the Work flat on the stone as it is being ground. Use long strokes at first, shorten them as the job approaches completion. First grind the face of the graver to the angle required. This may be judged "by eye" or with a C D E flat piece of sheet metal with a 45 ° angle filed in Figure 10-Graver Shapes it, The graver face must be made perfectly flat, any rounding of the corners will produce dull cutting The equipment found in most watchmakers' shops edges, Getting a flat surface depends upon keeping to harden and temper metals is a large alcohol lamp a steady finger pressure. The hand and arm motions and a small automatic blow torch, The steel is held should be sensitive and flexible enough to hold the on a charcoal block while being heated, The block face of the work flat against the stone at every part should be flat and large enough to support the entire of the motion to prevent "rocking" the work and piece. rounding the corners. After the graver face is ground, If, due to the form of the article to be hardened, the two undersides that meet at its point must be it does not touch the block along its entire form, the ground sufficiently to remove the roughness there on block may be hollowed or a backing may be made the new gravers, Where this is to be done is shown of smaller pieces of charcoal. These will catch heat at E without the angle and F with the angle ( the and hold it around the article to facilitate the heat undergrinding is slightly exaggerated), Besides ing, smoothing the surfaces, it places a supporting effect A large burning flame is directed on the article under the cutting edges and point of the graver and by a continuous blast from the blow torch. Heat is lessens the chance to break under the strain of turning. applied until the steel has become a cnerry red or The graver then should be smooth-stoned on a hard the correct specified temperature. When the piece is Arkansas stone so th~t there will be sharp cutting of an even red- color, it is instantly placed in cold edges where the surfaces meet. Good turning cannot water or oil for cooling. After hardening, steel will be done without well-kept gravers, be coated with a black oxide which is removed by cleaning ahd polishing, PART 5-HARDENING AND TEMPERING TEMPERING . OF STEEL-Due to its extreme OF STEEL brittleness, it is necessary to temper the hardened steel. Each piece being tempered or drawn until it HARDENING OF STEEL-There are many kinds is of the proper hardness for the specific purpose of steel but four general _purpose types of tool steel required. are widely used: Carbon or water-hardening, oil hardening, air-hardening and high speed steel. The There are several methods of judging the diminish watchmaking industry uses mainly the first two ing hardness under heat, The color method is usually water and oil-1).ardening steels. As we use only steel the most convenient. Each color denotes a certain of the very highest grade in our work and our tools, hardness. we must be doubly careful about heating in order The steel will first turn a very pale straw, sttaw, to prevent damaging the metals. Steel, as it comes dark straw, brown, purple, light purple, dark purple, from the manufacturer, is soft enough to be easily dark blue, light blue and then green. To obtain an filed, turned or drilled. After shaping the needed even color, the utmost cleanliness must be observed, part or tool, the steel is hardened to the required even a finger mark being sufficient to prevent a color temperature at the proper rate and then cooled in the that otherwise might have been perfect. proper liquid. The steel manufacturer usually indicates The finer and brighter the polish before tempering, on the stock the critical hardening point of the par the better and more even the color will be. The ticular ;ype of steel. hardened piece is laid on a metal plate or bluing pan Tools 7 Today with the increased precision of machinery necessary to convert measurements in one system to and the application of light and electricity to those of the other. measurement, measurements in millionths of an The relationship existing between the two systems inch are possible. of measuring is as follows: A great deal of agitation developed in continental METRIC AND ENGLISH CONVERSION TABLE Europe, especially in France, for a system of measur# 1 meter = 39.37 inches I yard = 0,9144 meter ing based on decimals which eventually lead to the 1 meter = 3.2808 feet 1 foot = 0,3048 meter 1 meter = 1.0936 yard 1 foot = 304.8 millimeters metric system whose unit of measure is one ten mil 1 centimeter = 0.397 inch 1 inch = 2.54 centimeters lionth of the distance from the equator to the pole, 1 millimeter = 0.03937 inch 1 inch = 25.4 millimeters measured on a meridian. This length is 39.37 + From this conversion table inches can be changed inches. to centimeters by multiplying the number of inches The meter is divided into o,;e hundred parts. Each by 2.54, or to millimeters by multiplying by 25.4. part is called a centimeter. Each centimeter is divided Likewise centimeters changed to inches hy multiply into ten parts each of which is called a millimeter. Of ing the number of centimeters by .3937 or change course there is a defiriite relation existing between the millimeters to inches by multiplying the number of English and metric system and it is possible and often millimeters by .03937.