Care and Handling of the Hamilton Marine Chronometer (c.1946)

HIRE llllll IIIIIIIIIIIIE nr me HIIIIIIl'I'IIII IIIIIIIIIIE (HHDIIOIIIE'I'EII gh ? HAMlLTON WATCH COMPANY LANCASTER. PENNSYLVANIA, u. s. A. HIRE nnn Illlllllllllli at me Illllllll'l'flll IIIIIIIIIIE tHIIDIIIIIIIE'I'ER HAMILTON WATCH COMPANY LANCASTER. PENNSYLVANIA, u. s. A. FOREWORD The Hamilton Marine Chronometer is a highly precisetimekeeper. Itscontinuedaccuracyandrelia‐ bility of performance are dependent upon the prac‐ tice of certain procedures in its care and handling. To those n o t experienced in the handling and main‐ tenance of chronometers, this manual provides in‐ structions which should be thoroughly read and understood before the instrument is moved or placed in service. To those others who a r e experienced in the care of chronometers, these instructions m a y serve as a review of the subject as well as to indi‐ cate certain particular characteristics of the Hamilton Marine Chronometer. For service information, which is not a provision of this manual, consult a fully qualified chronometer repairman or write to the Service Department of the Hamilton Watch Company. At the conclusion of the instructions there is in‐ cluded a series of log sheets intended for the record‐ ing of the chronometer rate at such times when another record form is n o t prescribed. CONTENTS Page FOREWORD .......................................... 2 TYPES OF HAMILTON MARINE CHRONOMETERS ....... 5 GENERAL CAUTIONS ................................. 6 PLACING CHRONOMETER INOPERATION ............. 7 POSITIONING .......‘................................. I3 WINDING ............................................ I3 REGULATING ........................................ I5 SETTING .............................................. I5 TRANSPORTATION .................................... I9 PREPARING CHRONOMETER FOR SHIPMENT ........... 20 CARE OFARUN-DOWN CHRONOMETER .............. 22 RECORDING THE CHRONOMETER RATE ............... 23 CHRONOMETER LOG SHEETS ......................... 26 TYPES OF HAMILTON MARINE CHRONOMETERS The instructions for care and handling outlined in this manual apply equally well to all types of Marine Chronometers manufactured by the Hamilton Watch Company. The several types employ essentially the same basic movement and differ from each other primarily in dial and hand arrangements. Three of the most common arrangements are illustrated below. The 12-Hour arrangement is the conventional style and is the type supplied to the U. S. Navy. The 24‐Hour type was created for those applications in which time is noted in terms of 24 rather than 12 hours and offers, of course, elimination of possible 5 confusion in the “A. M." and “P. M.” designations. The Individual-Orbit type is unique in that it pro‐ vides separate orbits for hours, minutes, seconds, day of the week, and wind indication. In the accom‐ panying illustration, the hour (24) track appears at the left, the minutes on the main central orbit, sec‐ onds at the right, days of the week at the bottom, and wind indication at the top. The Individual‐ Orbit type is particularly applicable for navigation in the Pacific zone where the day of the week hand indicates the Greenwich day and eliminates possible error resulting from local calendar change at the International Date Line. When making inquiries concerning any Hamilton Marine Chronometer, refer to the movement serial number which is duplicated on the number plates attached to the mounting box and the carrying case. File GENERAL CAUTIONS H a m i l t o n Marine Chronometers have proven rugged and reliable under service conditions with the United States Navy. They have survived with‐ out ill efl‘ect the greatest navalbombardments of all times. Yet, because of the inherent characteristics of the marine chronometer mechanism, damage m a y easily occur to the instrument in the hands of those unskilled in the care of Chronometers. Accordingly, 6 for the safety of the chronometer, the following chief precautions should be observed. 1. DO N O T move a chronometer when the main‐ spring is run down and the balance wheel is in a free-swinging condition without adhering to the instructions given under CARE OF A RUN-DOWN CHRONOMETER. Better ‐‐ never let a chronometer run down. 2. NEVER touch or interfere with the second hand. NEVER move the hour and minute hands counterclockwise. 3. Unless absolutely necessary, never remove the chronometer movement from its case. % PLACING CHRONOMETER IN OPERATION When a Hamilton Chronometer is received in ship‐ ment, particularly from the factory, the following conditionsaregenerallyfoundtoholdtrue. (1)Two packages comprise the shipment‐one containing the movement in its case and the other containing the carrying case and mounting box with the gimbal ring locked in the horizontal position. (2) The instru‐ ment is fully wound, asshown by the wind indicator onthedial. (3)Thebalancewheelisimmobilizedby two wedges located between the rim of the wheel 7 and the top surface of the train bridge. Generally, it will be found that these wedges consist of folded strips of a red plastic material, although wedges of tissue paper or cork may be employed. After the chrorfometer movement and boxes are removed from their shipping containers, it is neces‐ sary to take the movement from its case, remove the wedges from beneath the balance wheel, start and set the chronometer, and finally assemble the cased movement to the gimbal ring in the mounting box. The services of a skilled chronometer service man should be solicited for the performance of these op‐ erations. Under circumstances which require that a person unfamiliar with chronometers place the in‐ strument in operation, adherence to the following de‐ tailed procedure cannot be too strongly recommended. Remove the bezel containing the crystal from the case by turning it in the counterclockwise direction. Then, holding the chronometer above a table with one hand under the case, place fingertips of other band around edge of dial on the t o p side. Slowly invert the case, maintaining pressure upon the edge of the dial with the fingertips sothat the chronometer movement is not inadvertently allowed to fall from the case. Supporting the movement with the finger‐ tips against the edge of the dial, raise the case with the other hand, removing it from the movement. If the movement tends to stick in the case, the wind‐ ing key may be inserted through the back of the case as in winding and employed to push the movement free. Still holding the chronometer with one hand, place the empty case, open side up, on the table. 8 REMOVING BALANCE WHEEL WEDGES Finally, place the inverted movement on the case with the dial located in the shoulder recess around the top edge of the case. Gently remove the two wedges located between the balance wheel and the train bridge. As shown in the accompanying illustration, the wedges can be best removed with the aid of tweezers while the bal‐ ance wheel is maintained in position by a clean, non‐ metallic rod or pointer. Several precautions should be carefully observed at this point. During removal of the wedge, do not exert pressure against the bal‐ ance wheel; the wheel or staff may otherwise sufi'er damage. In removing a wedge of the folded type, whether of plastic or tissue paper material, care should be taken to extract it in such a manner that the fold of the wedge is not forced under the rim of the balance wheel. The two tails of the wedge can safely pass under the rimwhereas the extra thick‐ ness occurring at the fold end is sufiicient to distort the wheel if forced under the rim. Do not let the balance wheel start during removal of the wedges. Taking care to avoid imparting any rotary motion to the movement or the balance wheel, restore the chronometer movement to its case. Be certain that the alignment pin protruding beyond the movement enters its slot in the edge of the case. Before the bezel is replaced or the chronometer is assembled to the gimbal ring, it is best to first start and set the chronometer. Holding the chronometer with the dial horizontal, giveit a single quick twist to either the right or left. Observation of the second hand or the audible ticking will indicate the success‐ 10 ful performance of this operation. If the chronometer is so started when its second hand and that of a master time source are in agreement, the chronom‐ eter can be set very closely to the exact time. To then set the hour and minute hands, observe the in‐ structions given under SETTING. After this opera‐ tion has been successfully completed, assemble the bezel to the case. In assembling the chronometer to its gimbal ring in the mounting box, first retract the latch lever free‐ ing the empty gimbal ring. Tilt the gimbal ring forward, free the rear case pivot screw in the gimbal ring by backing off the large, knurled lock n u t sev‐ eral turns, and turn the pivot screw outward through several turns to permit entry of the chronometer case between the front and rear screws. With the gimbal ring tilted forward, carefully insert the cased chro‐ nometer into the ring, locating the end of the front pivot screw in its mating hole in the bracket at the front of the case. Then, still holding the case with the rear pivot screw aligned with its hole in the bracket at the rear of the case, turn the pivot screw clock‐ wise until it enters its bushing in the case bracket. The screw should be turned inward until very little clearance remains between the bushing in the bracket and the shoulder of the screw. Secure the screw in position by turning the lock nut against the gimbal ring. The completed assembly should have only a small amount of shake but should oscillate freely. Generally, adjustments of the gimbal assembly should always be confined to the rear case pivot 11 12 screw, if the level of the chronometer as established at the factory is to be maintained. POSITlONING A marine chronometer should, preferably,be placed on a firm supporting base in a location where it will be subject to a minimum of jars, vibration, wide ranges of temperature, dampness, and magnetic fields. WINDING While Hamilton Chronometers are designed to r u n a maximum of 56 hours on each full winding, they should preferably be wound regularly every ay. The following routine in the daily winding of the Chronometers is recommended: Gently revolve the chronometer case in its gimbals to face down; hold it steady in this position. Open keyhole by turning the shield plate on the bottom of the case to the right (clockwise) until the hole in the shield plate is aligned with the hole in the case bottom. Then, insert winding key and gently push it down. Wind to the left (counterclockwise). Seven half turns are required if the chronometer has been run‐ ning 24 hours since the last winding. .On the last half turn slow the winding motion so that contact with the full Wind stop control is made gently. 13 WINDING T H E CHRONOMETER Remove key from movement and return shield plate to its natural position; do not let it snap. Gently return the chronometer to its natural position. Check the wind indicator on the dial; winding should have moved the hand back (counterclock‐ wise) from about “24” to “0”. REGULATING Unlike most timekeeping instruments, the chro‐ nometer is not equipped with a conventional regu‐ lator and cannot, therefore, be regulated while it is running. Regulation of the rate can be made by adjustment of the timing weights on the balance wheel‐a rather delicate operation. Any attempt at regulation by other than a fully experienced chro‐ nometer repairman is extremely hazardous to the chronometer. SETTING When used as a marine navigational instrument, the hands of a chronometer are never set except when the instrument is started. As more fully ex‐ plained later under RECORDING T H E CHRO‐ NOMETER RATE, a record of the chronometer rate and the accumulated error is maintained and applied to the dial reading at the time of observa‐ 15 tion. Hence, for navigational purposes setting of the hands is unnecessary. If resetting the chronometer becomes necessary or desirable under other circum‐ stances, there are two possible alternate methods which may be employed. In the use of either method described below, these two cautions should always be observed. ( 1 ) Do not permit anything to touch the sec‐ ond hand. (2) Never move the hour and minute hands counterclockwise. By the first method, it is assumed that the chro‐ nometer will not be stopped to permit synchroniza‐ tion of the second hand with a master time source; hence, that only the hour and minute hands will be set. This method permits, of course, a maximum possible e r r o r of 30 seconds. T h e procedure is as follows: Latch the gimbal suspension. Unscrew the bezel containing the crystal and place it to one side. Place the winding key on the bright, square arbor at the center of the dial. As illustrated, turn the key by its shank‐not the handle. Observe the correct hour and minute from the master time source. Turn the hour and minute hands forward to a point exactly one-half minute behind the time indicated by the master time source by setting the minute hand-of the chronometer on its proper marker just as the second hand of the master time source passes its “30” marker‐(30 sec‐ onds ahead of the chronometer minute hand). 16 17 Finally, synchronize the minute and second hands of the chronometer by advancing the minute hand to the next minute marker at the same instant the second hand passes the “60” (or “00”) marker on its orbit. ' Obviously, considerable inconvenience results by use of the above described method if the chronometer is fast since the hands may be turned only in the clockwise direction. If this situation exists or if it is desirable to set the chronometer to the exact sec‐ ond, the following method is recommended: Remove the chronometer movement from its case and stop the balance wheel. Familiarity with these operations can be acquired from the two sections, P L A C I N G CHRONOMETER IN OPERATION and PREPARING CHRONOMETER FOR SHIP‐ MEN T. If the chronometer is fast, simply l e t it rest until the time indicated by the chronometer hands is “overtaken” by correct time as determined from an accurate master time source. At this instant, start the chronometer by twisting it to the right or left. Or, it m a y be desirable to wait until the chronometer reading is “slow” and proceed as described below. If the chronometer is slow, simply restart it at that instant when the chronometer second hand and that of the master time source are in agreement. Then, using the winding key, turn the hour and minute hands forward to correct time, being certain to place the minute hand on the proper marker as the second hand passes “60” on its orbit. 18 TRANSPORTATION If a chronometer is to be transported, e v e n f o r short distances by hand, lock the gimbals suspension by means of the latch lever. Free-swinging chro‐ nometers are vulnerable to damage from Violent os‐ cillations of the gimbal suspension system. If the chronometer is to be in transit for a period of 24 hours or more, it is essential, since the instru‐ ment is running, that provision be made for winding it daily. If there is a n y chance that the daily wind‐ ing will be omitted and particularly that the instru‐ ment may be allowed to run down, it is necessary that the balance assembly of the chronometer be im‐ mobilized, preferably by an experienced chronometer service man, before transportation is begun. 19 PREPARING CHRONOMETER FOR SHIPMENT The condition of achronometer prepared for ship‐ ment should be the same as that in which it was received from the factory. The following procedure should be carefully followed with the aid of an ex~ perienced chronometer repairman, if possible, partic‐ ularly for the immobilization of the balance assembly. First, fully wind the chronometer. Then, disas‐ semble the cased movement from the gimbal ring by backing off the r e a r case pivot screw in the gimbal ring. Remove the movement from its case, carefully following instructions given for this operation under PLACING CHRONOMETER IN OPERATION. Stop the balance wheel by applying a very light pressure with a clean, nonmetallic rod against the top edge of the wheel or with a fine camel’s hair brush against the periphery. L e t the wheel come to rest in its dead center position so that the spring no longer tends to pull the wheel in either direction. The wedges which were received with the chro‐ nometer should be employed again, but if unavail‐ able, two satisfactory replacements can be made by folding wedges from unbleached tissue paper. Insert the two wedges beneath the rim of the wheel at the extremities of the wheel spoke. It is well to employ tweezers in handling the wedges and to hold the wheel lightly in position by a nonmetallic tool in the other hand. Again, observe the precaution of 20 inserting the tails of the wedge beneath the rim, rather than the fold end. The wedges in their final positions should be located sufficiently securely that they will neither fall out easily, nor exert an extreme force against the wheel. After the wedges have been properly inserted, replace the movement in its case and screw the bezel on the case. Package the chronometer components in two car‐ tons. In one, enclose just the chronometer move‐ ment and its case, providing liberal padding as pro‐ tection against shock. In the other, pack the mount‐ i n g box and the carrying case assembled to each other in the normal fashion. The gimbal ring should be locked in position by the latch lever. The wind‐ ing key m a y be left in its receptacle in the corner of the mounting box, if it is held in position by a piece of cord or twine first inserted through the hole. The finished containers should, of course, be marked “fragile” and shipped by a method which will assure careful handling. It m a y be observed that the instruction plate in the l i d of the chronometer mounting box bears infor‐ mation apparently contrary to that given here in the matter of condition of wind of the chronometer and the subject of packaging. Each set of instructions has its particular applications. If it is known when the chronometer is prepared for shipment that it is likely to be inoperative for a considerable period, it is well to let it r u n down in order that mainspring stress will be a minimum. 21 Otherwise, it is recommended that the chronometer be fully wound. Relative to packaging, if the chronometer is to receive personal attention during transit, it is quite satisfactory to follow the procedure given on the in‐ struction plate. “Wedge” the balance wheel, wrap the cased movement with protective material, and place it in the mounting box within the carrying case. Where there is cause to suspect the degree of care exercised during transportation, the separate-carton method described here is recommended. fies CARE OF A RUN-DOWN CHRONOMETER A chronometer should never be permitted to run down, for in this state it is in a critical condition, highly susceptible to damage if not treated properly. Personnel not fully experienced in the service and repair of chronometers are warned to be especially careful to observe the following routine in the order noted in attempting to restart the instrument. Do n o t move the chronometer from its existing position. Slowly invert the chronometer and proceed with winding as described under WINDING. Note that when the chronometer is completely run down, 171/2 half turns will be required to fully wind it. Gently return the chronometer to its normal position. To start the chronometer, grasp the box with both 22 hands, letting the box remain on its table or other support, and give the whole unit a single quick twist to the right or left. As previously mentioned, if the chronometer is started in this manner when the sec‐ ond hand of a master time source and that of the chronometer are in agreement, the chronometer can be set very closely to the exact time. It will, of course, be necessary to then set the hour and minute hands as described under SETTING. (ck RECORDING THE CHRONOMETER RATE Accurate time indications from a chronometer are dependent upon careful observation of the dial read‐ ing and the application of an accumulated e r r o r factor to the dial reading. Under these conditions the maintenance of some record of the chronometer r a t e is essential. Where circumstances prescribe no other method, the following general procedure is recommended. Daily, or at any other convenient intervals, check the dial reading of the chronometer against an au‐ thoritative time standard, such as those maintained by the Naval Observatory or the Bureau of Stand‐ ards, both of which periodically transmit accurate time signals. It is, of course, convenient to employ a comparing watch for intercomparison with the time signal and the chronometer, although it should 23 be remembered that an additional observational error is introduced by use of this method. By either means, it is very simple to arrive at the dial error factor, the difference between exact time and that indicated by the chronometer. , Since the chronome‐ ter hands advance in one-half second increments, the dial error can best be recorded to the nearest one‐ half second. Determine the average rate (that is the gaining or losing rate of the chronometer) by calculating the difference of the dial error between successive readings. If these dial error readings are recorded daily, the rate then, of course, is an indication of the time gained or lost per day. When observations are made several days apart, the rate should be re‐ duced to a per diem (24-hour) basis by dividing the difference in dial errors by the number of days in‐ volved. Even when the rates are recorded daily, it is generally necessary to average the rates for an extended number of days to arrive at the actual rate of the chronometer because of the fractional errors occurring through recognition of the dial reading to only the nearest one-half second. It is this average daily rate established over an interval of days which is employed for the computation of exact time when the chronometer has n o t been checked against a master source for any extended period. This recommended method can be easily under‐ stood from the accompanying l o g sheet. Under “Remarks” it is well to record any unusual circum‐ stances, such as when the chronometer has been started or stopped, set, moved in location, etc. These 24 disturbances of the instrument may each exert an influence upon the rate and, hence, should be noted for the sake of identification of possible causes of fluctuations in rate. Incidentally, the temperature compensation error of the Hamilton Marine Chro‐ nometer is negligible; thus, a temperature record need not be maintained or a coefficient established under normal operation conditions. Date Average Rate + = Gaining ‐ == Losing ‐shirred45e? ’ (Ht/y, dbl/y fdfe : 74/4 539 SAMPLELOGSHEET 25 2 day Ally, CHRONOMETER LOG Hamilton Marine Chronometer Serial No. + - Gaining CHRONOMETER LOG Hamilton Marine Chronomter Serial No. Dial Error Rate + = Gaining -‐ - Losing Remarks CHRONOMETER LOG Hamilton Marine Chronometer Serial No. CHRONOMETER LOG Hamilton Marine Chronometer Serial No. Dial Error +--Fnst ‐- - Slow Average Rate - Gaining ‐ = Lorin; Remarks CHRONOMETER LOG Hamilton Marine Chronometer Serial N o . Rate + - Gaining Remarks CHRONOMETER LOG Hamilton Marine Chronometer Serial No. Date Average - Fast Rate Remarks Dial Error = Slow a Gaining -‐‐= Losing