Transcriber's notes:Some minor typographical errors have been corrected. The author's spelling has been retained. A TREATISE ON STAFF MAKING AND PIVOTING CONTAINING COMPLETE DIRECTIONS FOR MAKING AND FITTING NEW STAFFS FROM THE RAW MATERIAL EUGENE E. HALL WITH NUMEROUS ILLUSTRATIONS CHICAGO: HAZLITT & WALKER, PUBLISHERS 1910 CONTENTS. CHAPTER I. The raw material. The gravers. The roughing out. The hardeningand tempering 5 CHAPTER II. Kinds of pivots. Their shape. Capillarity. The requirements ofa good pivot 13 CHAPTER III. The proper measurements and how obtained 19 CHAPTER IV. The gauging of holes. The side shake. The position of the graver 23 CHAPTER V. The grinding and polishing. The reversal of the work. The waxchuck 29 CHAPTER VI. Another wax chuck. The centering of the work 35 CHAPTER VII. The finishing of the staff. Pivoting. Making pivot drills. Hardeningdrills. The drilling and fitting of new pivots 39 STAFF MAKING AND PIVOTING. CHAPTER I. To produce a good balance staff requires more skill than to produce anyother turned portion of a watch, and your success will depend not aloneon your knowledge of its proper shape and measurements, nor the tools atyour command, but rather upon your skill with the graver and your successin hardening and tempering. There are many points worthy of considerationin the making of a balance staff that are too often neglected. I haveseen staffs that were models as regards execution and finish, that werenearly worthless from a practical standpoint, simply because the makerhad devoted all his time and energy to the execution of a beautiful pieceof lathe work, and had given no thought or study to the form and size ofthe pivots. On the other hand, one often sees staffs whose pivots arefaultless in shape, but the execution and finish so bungling as to offsetall the good qualities as regards shape. To have good tools and the rightideas is one thing, and to use these tools properly and make a practicaldemonstration of your theory is another. I shall endeavor to take up every point in connection with the balancestaff, from the steel to the jewels, and their relation to the pivots, and I believe this will then convey to the reader all the necessarypoints, not only as regards staffs, but pivots also, whether applied to abalance or a pinion staff. It may be argued, and we often do hear material dealers advance thetheory, that to-day, with our interchangeable parts and the cheapness ofall material, it is a waste of time to make a balance staff. To thereader who takes this view of the situation I simply want to say, kindlyfollow me to the end of this paragraph, and if you are still of the sameopinion, then you are wasting your time in following me farther. For amaterial dealer to advance this theory I can find some excuse; he is aninterested party, and the selling of material is his bread and butter;but the other fellow, well I never could understand him and possiblynever shall. When we seriously consider the various styles and series in"old model" and "new model, " of only one of the leading manufacturers ofwatches in this country, to say nothing of the legion of small and largeconcerns who are manufacturing or have manufactured in the past, and thenthink of carrying these staffs in stock, all ready for use, we then beginto realize how utterly absurd the idea is, to say nothing of howexpensive! On the other hand, if you reside in a large city and proposeto rely on the stock of your material dealer, you will find yourself inan embarrasing situation very often, for as likely as not the movementrequiring a new staff was made by a company that went out of businessback in the '80s, or it is a new movement, the material for which hasnot yet been placed on the market. This state of affairs leads tomakeshifts, and they in turn lead to botch work. The watchmaker who doesnot possess the experience or necessary qualifications to make a newbalance staff and make it in a neat and workmanlike manner, is nevercertain of having exactly what is needed, and cannot hope to long retainthe confidence of his customers. In fact, he is not a watchmaker at all, but simply an apprentice or student, even though he be working for asalary or be his own master. There are undoubtedly many worthy members ofthe trade, who are not familiar with the making of a balance staff, whowill take exceptions to this statement; but it is nevertheless true. Theymay be good workmen as far as they go; they may be painstaking; but theycannot be classed as watchmakers. This article is intended for the benefit of that large class whoseopportunities for obtaining instruction are limited, and who are readyand willing to learn, and for that still larger class of practicalworkmen who can make a new staff in a creditable manner, but who arealways glad to read others people's ideas on any subject connected withthe trade and who are not yet too old to learn new tricks should theyfind any such. [Illustration: _Fig. 1. _] Good tools, in good condition, are the most essential requisites inmaking a new staff. I would not advise any particular make of lathe, asthe most expensive lathe in the world will not produce a true staff ifthe workman cannot center his work accurately and does not know how tohandle his graver, while on the other hand fine work can be done on thesimplest and cheapest lathe by a workman possessing the requisite skill. I will take it for granted that you use an American-made lathe of somekind, or a foreign-made lathe manufactured on American lines. It isadvisable, though not absolutely necessary, to have three gravers similarto those illustrated in Fig. 1, A being used for turning the staff downin the rough; B for the conical pivots and square shoulders and C for theunder-cutting. The other tools and attachments needed will be describedas I come to them in use. The balance staff should be made of the best steel, tempered to such adegree as to give the longest service and yet not so hard as to endangerthe breakage of the pivots. Select a piece of Stubb's steel wire, say No. 46, or a little larger than the largest part of the finished staff is tobe, and center it in a split chuck of your lathe. Be careful in selectingyour chuck that you pick one that fits the wire fairly close. The chuckholds the work truest that comes the nearest to fitting it. If you try touse a chuck that is too large or too small for the work, you will onlyruin the chuck for truth. Turn the wire to the form of a rough staff, asshown in Fig. 2, leaving on a small part of the original wire, as shownat A. After the wire is roughed out to this general form, remove from thechuck and get ready to harden and temper it. The hardening and temperingmay be effected in various ways, and I am scarcely prepared to say whichmethod is the best, as there are several which give about the samegeneral results. One method of hardening is to smear the blank withcommon yellow soap, heat it to a cherry red, and drop endwise intolinseed oil. Petroleum is preferred by some to linseed oil, but, to tellthe truth, I can see no difference in the action of linseed, petroleum orolive oil. Be sure and have enough oil to thoroughly cool the blank, anda deep vessel, such as a large-mouthed vial, is preferable to a saucer. The blank will now be found too hard to work easily with the graver, andwe must therefore draw the temper down to that of fine spring steel. Before doing this the blank should be brightened, in order that we maysee to just what color we are drawing it. The main object in using thesoap in hardening is that it may form a scale upon the blank, and if theheating is effected gradually the soap will melt and form a practicallyair-tight case around the blank. This scale, if the hardening iscarefully and properly done, will generally chip and fall off when theblank is plunged in the oil, particularly if the oil is cool, and if itdoes not fall off of its own accord, it can easily be removed by rollingthe blank upon the bench. If it does not come out clean, or if soap isnot used, it may be brightened by again inserting in the lathe andbringing it in contact with a piece of fine emery paper or cloth. [Illustration: _Fig. 2. _] I draw the temper in the following manner: Place some fine brass filingsin a boiling-out cup or bluing pan and lay the blank upon these filings, holding the pan over the flame of an alcohol lamp until the blank assumesa dark purple color, which it will reach when the heat gets to about 500°F. This I consider the right hardness for a balance staff, as it is nottoo hard to work well under the graver nor too soft for the pivots. Atthis degree of hardness steel will assume an exquisite polish if properlytreated. Another method of tempering is to place the staff on a piece ofsheet iron or copper (say 1 inch wide by 4 long), having previously bentit into a small angle, for the reception of the staff, as shown in Fig. 3. This piece of metal, when nicely fitted into a file handle, willanswer all the purposes of the bluing pan and presents quite a neatappearance. Having placed the blank in the angle, lay on it a piece ofyellow wax about the size of a bean, and heat it over your lamp until thewax takes fire and burns. Blow out the flame and allow the staff to cool, and it will be found to be of about the right hardness. [Illustration: _Fig. 3. _] We have now arrived at an important station in staff making, a junction, we may term it, where many lines branch off from the main road. At thisparticular spot is where authorities differ. I have no hesitation insaying that at this particular point the split chuck should be removedfrom the lathe head and carefully placed in the chuck box and the cementchuck put in its place. I believe that all of the remaining work upon astaff should be executed while it is held in a cement chuck. On the otherhand I have seen good workmen who turned and finished all the lower partof a staff while in a split chuck, cut it off and turned and finished theupper part in a cement chuck. All I have got to say is that they had moreconfidence in the truth of their chucks than I have in mine. I have evenread of watchmakers who made the entire staff in a split chuck, but Imust confess I am somewhat curious to examine a staff made in that way, and must have the privilege of examining it before I will admit that atrue staff can be so made. We will suppose that the workman has a moderately true chuck, and that heprefers to turn and finish all the lower portions in this way. Of coursethe directions for using a cement chuck on the upper part of a staff areequally applicable to the lower. Before going further I think itadvisable to consider the requirements of a pivot, but will reserve thisfor another chapter. CHAPTER II. The chief requirements of a pivot are that it shall be round and wellpolished. Avoid the burnish file at all hazards; it will not leave thepivot round, for the pressure is unequal at various points in therevolution. A pivot that was not perfectly round might act fairly well ina jewel hole that was round, but unfortunately the greater proportion ofjewel holes are not as they should be, and we must therefore take everyprecaution to guard against untrue pivots. Let us examine just what theeffect will be if an imperfect pivot is fitted into an unround holejewel, and to demonstrate its action more clearly let us exaggerate thedefects. Suppose we pick a perfectly round jewel and insert into theopening a three-cornered piece of steel wire, in shape somewhatresembling the taper of a triangular file. We find that this triangularpiece of steel will turn in the jewel with the same ease that the mostperfect cylindrical pivot will. Now suppose we change the jewel for onethat is out of round and repeat the experiment. We now find that thetriangular steel soon finds the hollow spots in the jewel hole and comesto a stand-still as it is inserted in the hole. The action of a pivotthat is not true, when in contact with a jewel whose hole is out ofround, is very similar, though in a less marked degree. If the pivotinclines toward the elliptical and the jewel hole has a like failing, which is often the case, it is very evident that this want of truth inboth the pivot and hole is very detrimental to the good going of a watch. [Illustration: _Fig. 4. _] [Illustration: _Fig. 5. _] There are two kinds of pivots, known respectively as straight and conicalpivots, but for the balance staff there is but one kind and that is theconical, which is illustrated in Fig. 4. The conical pivot has at leastone advantage over the straight one, _i. E. _, it can be made much smallerthan a straight pivot, as it is much stronger in proportion, owing to itsshape. All pivots have a tendency to draw the oil away from the jewels, and particularly the conically formed variety, which develops a strongcapillary attraction. To prevent this capillary attraction of the oil, the back-slope is formed next to the shoulder, although many persons seemto think that this back-slope is merely added by way of ornament, to makethe pivot more graceful in appearance. It is very essential, however, forif too much oil is applied the staff would certainly draw it away if itsthickness were not reduced, by means of the back-slope. Before leavingthe subject of capillarity let us examine the enlarged jewel in Fig. 5;_c_ is an enlarged pivot, _b_ is the hole jewel and _a_ is the end stone. We observe that the hole jewel on the side towards the end stone isconvex. It is so made that through capillarity the oil is retained atthe end of the pivot where it is most wanted. It is, in my opinion, verynecessary that the young watchmaker should have at least a fairunderstanding of capillarity, and should understand why the end stone ismade convex and the pivot with a back slope. For this reason I will tryand make clear this point before proceeding further. We all know that itis essential to apply oil to all surfaces coming in contact, in order toreduce the friction as much as possible, and if the application of oil isnecessary to any part of the mechanism of a watch, that part is thepivot. Saunier very aptly puts it thus: "A liquid is subject to theaction of three forces: gravity, adhesion (the mutual attraction betweenthe liquid and the substance of the vessel containing it), and cohesion(the attractive force existing among the molecules of the liquid andopposing the subdivision of the mass. )" We all know that if we place a small drop of oil upon a piece of flatglass or steel and then invert the same the oil will cling to the glass, owing to the adhesion of the particles; if we then add a little more tothe drop and again invert, it will still cling, although the drop may beelongated to a certain degree. This is owing to the cohesion of themolecules of the oil, which refuse to be separated from one another. If, however, we again add to the drop of oil and invert the plate the dropwill elongate and finally part, one portion dropping while the otherportion clings to the main body of the liquid. The fall of the drop isoccasioned by gravity overcoming the cohesion of the molecules. Now takea perfectly clean and polished needle and place a drop of oil upon itspoint and we will see that the oil very rapidly ascends towards thethicker portion of the needle. Now if we heat and hammer out the point ofthe needle into the form of a small drill and repeat the operation wefind that the oil no longer ascends. It rises from the point to theextreme width of the drill portion, but refuses to go beyond. It clingsto that portion of the needle which would correspond to the ridge justback of the slope in a conical pivot. Water, oil, etc. , when placed in aclean wine glass, do not exhibit a perfectly level surface, but raise atthe edges as shown at _a_ in Fig. 6. If a tube is now inserted, we findthat the liquid not only rises around the outside of the tube and theedges of the vessel, but also rises in the tube far beyond its meanlevel, as shown at _b_. These various effects are caused by one of theforces above described, _i. E. _, the adhesion, or mutual attractionexisting between the liquid and the substance of the vessel and rod. Theword capillarity is of Latin derivation, and signifies hair-likeslenderness. The smaller the tube, or the nearer the edges of a vesselare brought together, the higher in proportion will the liquid rise abovethe level. An ascent of a liquid, due to capillarity, also takes place, where the liquid is placed between two separate bodies, as oil placedbetween two pieces of flat glass. If the plates are parallel to oneanother and perpendicular to the surface of the liquid it will ascend tothe same height between the plates, as shown at _c_ in Fig. 6. If theplates were united at the back like a book and spread somewhat at thefront, the oil would ascend the higher as the two sides approach oneanother, as shown at _d_, Fig. 6. If a drop is placed somewhat away fromthe intersecting point, of the glasses, as shown at _m_ it will, if nottoo far away, gradually work its way to the junction, providing theglasses are level. If, however, the glasses are inclined to a certainextent, the drop will remain stationary, since it is drawn in onedirection by gravity and in the other by capillarity. When a drop of oilis placed between two surfaces, both of which are convex, or one convexand the other plain, as shown at _g_, it will collect at the point _n_, at which the surfaces nearest approach one another. We now see veryclearly why the hole jewel is made convex on the side towards theend-stone and concave on the side towards the pivot. [Illustration: _Fig. 6. _] Particular pains should be taken to polish those portions of the pivotswhich actually enter the jewel hole and to see that all marks of thegraver be thoroughly removed, because if any grooves, no matter howsmall, are left, they act as minute capillary tubes to convey the oil. If the hole jewel be of the proper shape, the end-stone not too far fromthe hole jewel and too much oil is not applied at one time, the oil willnot spread nor run down the staff, but a small portion will be retainedat the acting surface of pivot and jewel, and this supply will begradually fed to these parts from the reservoir between the jewel andend-stone, by the action of capillarity. Having examined into the requirements of the pivot and its jewel andhaving gained an insight into what their forms should be, we are thebetter able to perform that portion of the work in an intelligentmanner. CHAPTER III. Our wire has been roughed out into the form of a staff, has been hardenedand the temper drawn down to the requisite hardness and we are now readyto proceed with our work. As I said before, we have now arrived at apoint where many authorities differ, _i. E. _, as to whether the finishingof the staff proper, should be performed while the work is held in thechuck, or whether a wax chuck be substituted. We will take it for grantedthat you have a true chuck and that you prefer to finish all the lowerportion of the staff while held in the chuck. Before we proceed with our work it will be necessary for us to make someaccurate measurements, as we cannot afford to do any guess work bymeasuring by means of the old staff. I have used a number of differentkinds of calipers and measuring instruments for determining the variousmeasurements for a balance staff, but have met with more success with avery simple little tool which I made myself from drawings and descriptionpublished some years ago in THE AMERICAN JEWELER. This simple little toolis shown in Fig. 7, and has been of great service to me. It consists of abrass sleeve A, with a projection at one end as shown at B. This sleeveis threaded, and into it is fitted the screw part C, which terminates ina pivot D, which is small enough to enter the smallest jewel. The sleeveI made from a solid piece of brass, turning it down in my lathe andfinishing the projection by means of a file. The hole was then drilledand threaded with a standard thread. The screw part C, I made of steeland polished carefully. [Illustration: _Fig. 7. _] To ascertain the proper height for the roller, place it upon the tool, allowing it to rest upon the leg B, and set the pivot D in the footjewel. Now adjust, by means of the screw C until the roller is in itsproper position in relation to the lever fork. This may be understoodbetter by consulting Fig. 8, where A is the gauge, C is the roller, E isthe lever, F is the plate and G is the potance. [Illustration: _Fig. 8. _] Now in order to locate the proper place to cut the seat for the roller, remove it from the foot of the gauge and apply the gauge to the work asshown in Fig. 9. The foot of the gauge resting against the end of thepivot, the taper end of the gauge will locate accurately the position ofthe roller seat. In order to locate the proper position for the seat forthe balance, proceed the same as for the roller, except that the foot ofthe gauge is lowered until it is brought sufficiently below the plate toallow of the proper clearance as indicated by the dotted lines at H. Nowapply the gauge to the new staff, as shown in Fig. 10, and the taper endwill locate the exact position for the balance seat. [Illustration: _Fig. 9. _] [Illustration: _Fig. 10. _] As previously stated, I have taken it for granted that you preferred tofinish all the lower portion of the staff while the work was held in thechuck. I have assumed that you prefer to work in this way because I havenoted the fact that nine watchmakers out of every ten start with, andfirst finish up, the lower portion of the staff. Where this method ofworking originated I do not know, but it always has the appearance to meof "placing the cart before the horse. " I do not pretend to say that atrue staff cannot be made in this way, but it certainly is not the mostconvenient nor advisable. We all know that the heaviest part of the staffis from the roller seat to the end of the top pivot. Now it seems to methat it is the most natural thing in the world for a mechanic to desireto turn the greater bulk of his work before reversing it. Now if theworkman has been educated to turn indifferently with right or left hand, it may make little difference, as far as the actual turning is concerned, whether he starts to work at the upper or lower end of the staff, butunfortunately there are few among us who are so skilled as to use thegraver with equal facility with either hand, and it is therefore anadvantage to start with the upper end, as you can thus finish a greaterportion of the work more readily. You can readily see that when you cometo reverse your staff and use the wax chuck, that by starting at the topof staff your wax has a much larger surface of metal to cling to, andagain the shape of the balance seat is such as to secure the work firmlyin the wax, while if the reverse method is employed, the larger portionof the balance seat is exposed and the staff is more liable to loosenfrom the motion of the lathe and pressure of the graver and polishers. CHAPTER IV. By the aid of the pinion calipers and the old staff, the diameter of theroller seat and the balance and hair-spring collet seats may be readilytaken, but it is perhaps better to gauge the holes, as the old staff maynot have been perfect in this respect. A round broach will answeradmirably for this purpose, and the size may be taken from the broach bymeans of the calipers. In fitting our pivots, we can not be too exact;and as yet no instrument has been placed upon the market for this purposewhich is moderate in price and yet thoroughly reliable. The majority ofwatchmakers use what is termed the pivot-gauge, a neat little instrumentwhich accompanies the Jacot lathe, and which may be obtained from anymaterial house. This tool, which is shown in Fig. 11, is, however, opento one objection in the measurement of pivots, and that is that it may bepressed down at one time with greater force than at another, andconsequently will show a variation in two measurements of the same pivot. Some of my readers may think that I am over-particular on this point, andthat the difference in measurement on two occasions is too trivial to beworthy of attention, but I do not think that too much care can bebestowed upon this part of the work, and neglect in this particular is, I think, the cause of poor performance in many otherwise goodtimepieces. The ordinarily accepted rule among watchmakers is that apivot should be made 1/2500 of an inch smaller than the hole in the jewelto allow for the proper lubrication. I am acquainted with watchmakers, and men who are termed good workmen, too, who invariably allow 1/2500 ofan inch side shake, no matter whether the pivot is 12/2500 or 16/2500 ofan inch in diameter. Now if 1/2500 of an inch is the proper side shakefor a pivot measuring 12/2500 of an inch in diameter, it is certainly notsufficient for a pivot which is one-third larger. Of course it isunderstood that side shakes do not increase in proportion according asthe pivot increases in size, for if they did a six-inch shaft wouldrequire at this rate a side shake of 1/2 inch, or 1/4 inch on each side, which would be ridiculously out of all proportion, as the 1/64 of an inchwould be ample under any circumstances. Neither can we arrive at theproper end shake for a pivot by reducing in proportion from the end shakeallowed on a six-inch shaft, because if we followed out the same courseof reasoning we would arrive at a point where a pivot measuring 12/2500of an inch would require an end shake so infinitely small that it wouldrequire six figures to express the denominator of the fraction, and themost minute measuring instrument yet invented would be incapable ofrecording the measurement. We must leave sufficient side shake, however, on the smallest pivot and jewel for the globules of the oil to movefreely, and experiments have shown conclusively that 1/2500 of an inch or1/5000 on each side of the pivot, is as little space as it is desirableto leave for that purpose, as the globules of the best chronometer oilwill refuse to enter spaces that are very much more minute. But to returnto our pivot gauge. [Illustration: _Fig. 11. _] [Illustration: _Fig. 12. _] Each division on the gauge represents 1/2500 of an inch, which is allthat we require. The diameter that the pivot should be, can beascertained by inserting a round pivot broach into the jewel and takingthe measurement with the pivot gauge, and then making the necessarydeduction for side shake. Slip the jewel on the broach as far as it willgo, as shown in Fig. 12, and then with the pivot gauge, take the size ofthe broach, as close up to the jewel as you can measure, and the taper ofthe broach will be about right for the side shake of the pivot. If, however, you prefer to make the measurement still more accurate, you cando so by dipping the broach into rouge before slipping on the jewel andthen remove the jewel and the place which is occupied on the broach canbe plainly discerned and the exact measurement taken and an allowance of1/2500 of an inch made for the side shake. Another method, and one whichis particularly applicable to Swiss watches, where the jewel is burnishedinto the cock or plate, is to first slip on to the broach a small flatpiece of cork and as the broach enters the jewel the cork is forcedfarther on to the broach, and when the jewel is removed it marks theplace on the broach which its inner side occupied, and the measurementcan then be taken with the gauge. If care is used in the selection of abroach, that it be as nearly perfect in round and taper as possible, by alittle experiment you can soon ascertain just what part of the length ofthe broach corresponds to one degree on the gauge and by a repetition ofthe experiment the broach can then be divided accurately, by very minuterings turned with a fine-pointed graver, into sections, each representingone degree, or 1/2500 of an inch, and the measurement will thus besimplified greatly. [Illustration: _Fig. 13. _] As before stated, much depends upon the condition of your gravers and themanner of using them. It is of the utmost importance that they be keptsharp, and as soon as they begin to show the slightest sign of losingtheir keenness, you should sharpen them. The proper shape for balancepivots was shown in Fig. 4. Now let us examine into the best positionsfor holding the gravers. In Fig. 13 two ways of holding the graver areshown, _A_ representing the right and _B_ representing the wrong way. Ifthe graver is applied to the work as shown at _A_, it will cut a cleanshaving, while if applied as shown at _B_ it will simply scrape the sideof the pivot and ruin the point of the graver without materiallyforwarding the work. Again, the holding of the graver as indicated at _A_has its advantages, because the force of the cut is towards the handholding it, and should it catch from any cause the jar of the obstructionwill be conveyed immediately to the hand, and it will naturally give andno harm will be done. If, on the other hand, the graver should meet withan obstruction while held in the position indicated at _B_, the force ofthe cut will be in the direction of the arrow, downward and toward therest, and the rest being unlike the hand, or rather being rigid, itcannot give, and the result is that the work, or graver, or both, areruined. In Fig. 14 two other methods of holding the graver are shown. Thegeneral roughing out of a staff should be done with the graver held aboutas shown at _A_, Fig. 13; but in finishing, the graver should be held sothat the cut is made diagonally, as indicated at _A_, Fig. 14. It israther dificult to explain in print just how the graver should be held, but a little experiment will suffice to teach the proper position. Thebest indication that a graver is doing its work properly, is the factthat the chips come away in long spiral coils. Aim to see how light a cutyou can make rather than how heavy. Never use force in removing thematerial, but depend entirely upon the keenness of the cutting edges. Never use the point of the graver, except where you are compelled to, butrather use the right or left hand cutting edges. By following out thisrule you will find that your work, when left by the graver, requireslittle or no finishing up, except at the pivots. At _B_, Fig. 14, isshown the correct manner of applying the graver when turning a pivot. Hold the graver nearly on a line with the axis of the lathe and catchinga chip at the extreme end of the pivot with the back edge of the graver, push slightly forward and at the same time roll the graver towards youand it will give the pivot the desired conical form. By keeping thegraver on a line with the length of the pivot, all the force applied issimply exerted in the direction of the chuck, and does not tend to springthe pivot, as it would were the extreme point applied, as in Fig. 13. When we come to such places as the shoulder of the back slope, the seatfor the roller, balance, etc. , we must necessarily use the point of thegraver. [Illustration: _Fig. 14. _] CHAPTER V. In chapter IV I called attention to the right and wrong way of holdingthe graver while using the extreme point, and also the correct manner ofapplying the graver in turning conical pivots. I also called attention tothe fact that it was well to only use the point of the graver wherepositively necessary, as in the back slope of the pivot, etc. In turningthe seat for the balance, as indicated at A, Fig. 15, the graver A, Fig. 1, or a similar one as shown at B, Fig. 15, should be used. The slope atC should now be turned. In turning the pivot and seat for the roller, youshould leave them slightly larger than required, to allow for thegrinding and polishing which is to follow. No definite amount can be leftfor this purpose, because the amount left for polishing depends entirelyon how smoothly your turning has been done. If it has been doneindifferently, you may have to allow considerable for grinding andpolishing before all the graver marks are removed, while, on thecontrary, if the work has been performed with care, very little will haveto be removed. Avoid the use of the pivot file by performing your workproperly to start with. [Illustration: _Fig. 15. _] [Illustration: _Fig. 16. _] For grinding, bell-metal or soft iron slips are desirable, and thegrinding is effected by means of oil stone powder and oil. Two slips ofmetal similar in shape to A and B, Fig. 16, are easily made, and will befound very useful. A is for square pivots, etc. , while B is used forconical pivots. These slips should be dressed with a dead smooth file, the filing to be done crosswise, to hold the oil stone powder and oil. During the operation of grinding, the lathe should be run at a high speedand the slips applied to the work lightly, squarely and carefully. Thepolishing is effected by means of diamantine and alcohol. After the workis brought to a smooth gray surface, slips of boxwood of the shape shownin Fig. 16 should be substituted for the metal slips. Oil stone slips aresometimes used in lieu of metal ones, but they soon get out of shape andare troublesome to care for on this account. All things considered, thereis nothing better for polishing than a slip or file made of agate, sayone inch long, one-quarter inch wide and one-eighth inch thick. A slip ofthis kind can be obtained from any lapidary, and after grinding withemery and water until the surface has a very fine grain, it should bemounted by fastening with cement into a brass socket and this is theninserted into a small wooden handle, as shown in Fig. 17. The agate slipshould be ground to about the shape of B, Fig. 16, so that one side canbe used for square corners and the other for conical pivots. The finalpolish can soon be imparted by means of a small boxwood slip, orflattened peg-wood, and diamantine and alcohol. Never try to bring outthe final polish until you are satisfied that all graver marks have beenground out, otherwise you will simply have to go all over the work again. [Illustration: _Fig. 17. _] When the staff is finished from the lower pivot to the seat of thebalance, the upper part should be roughed out nearly to size and then cutoff preparatory to finishing the top part. Attention was previously called to the fact that the majority ofwatchmakers prefer to finish all the lower portion of the staff first, notwithstanding the fact that there are numerous advantages to be gainedby proceeding to first finish up the upper portion. We have now reachedthe point where the wax chuck must be used, and perhaps these advantagesmay be now more clearly defined. In order that the two procedures may bemore distinctly shown, illustrations of both methods are here given. Fig. 18 shows the popular method, the lower portion of the staff beingall completed and fastened by means of wax, in the wax chuck. Fig. 19shows the opposite course of procedure. In both illustrations the linesindicate the amount of wax applied to hold the work. It will be notedthat in Fig. 18 the hub of the staff is enclosed in the wax very much asa cork is fitted into a bottle, while in Fig. 19 the hub is reversed, just as a cork would appear were the larger portion within the bottle andthe smaller portion protruding through the neck. A study of the diagramwill readily show that in Fig. 19 the staff is held more rigidly in placeand that a greater bulk of the work is enclosed in the wax than in Fig. 18, although there is less wax used in the former than in the latter. [Illustration: _Fig. 18. _] [Illustration: _Fig. 19. _] Before proceeding to set the staff in the wax, it is necessary to makesome measurements to determine its full length. Remove both cap jewelsand screw the balance cock in place. Examine the cock and see if it hasat any time been bent up or down or punched to raise or lower it. If so, rectify the error by straightening it and then put it in place. Now witha degree gauge, or calipers, proceed to take the distance between theouter surfaces of the hole jewels and shorten the staff to the requiredlength. Do not remove too much, but leave the staff a little long ratherthan cut it too short, as the length can be shortened later. [Illustration: _Fig. 20. _] [Illustration: _Fig. 21. _] A very handy tool for the purpose of making these length measurements canbe constructed by adding a stop screw to the common double calipers asshown in Fig. 20. The improvement consists in the fact that they can beopened to remove from the work and closed again at exactly the sameplace, so that an accurate measurement can be made. The all-importantpoint in the use of wax chucks is to get a perfect center. If you are notcareful you are liable to leave a small projection in the center as shownat A, Fig. 21. The ordinary wax chuck cannot be unscrewed from thespindle and restored to its proper place again with anything like acertainty of its being exactly true, and if you insist on doing thisthere is no remedy left but finding a new center each time. It will befound more satisfactory and economical in the long run to have apermanent chuck for a wax chuck and you will then have no necessity forremoving the brass chuck. The center, or cone for the reception of the pivot, should be turned outwith the graver at an angle of about 60° and such a graver as is shown atB, Fig. 1, will answer admirably for this purpose. After you havecarefully centered your wax chuck, place a small alcohol lamp under thechuck and heat it until the wax will just become fluid and yet not be hotenough to burn the wax. Revolve the lathe slowly and insert the staff sothat the pivot rests squarely and firmly in the center. Now re-heat thechuck carefully in order that the wax may adhere firmly to the staff, keeping the lathe revolving meanwhile, but not so fast that the wax willbe drawn from the center, and at the same time apply the forefinger tothe end of the staff, as shown in Figs. 18 and 19, and gently press itsquarely into place in the wax chuck. The lines in Figs. 18 and 19designate about the right amount of wax after the work is ready, but itis well to add a little more than is shown in those figures, and youshould be careful to keep the wax of equal bulk all around, or when itcools it will have a tendency to draw the staff to one side. Now removethe lamp and keep the lathe revolving until the wax is quite cool, whenit should be removed, by means of a graver, down to the dimensionsdesignated by the lines in Figs. 18 and 19. When this is accomplishedre-heat a little, but only enough to make it soft, but not liquid, andplacing a sharpened peg-wood on the tool rest proceed to the final truingup, by resting the pointed end against the hub. CHAPTER VI. I have described above one of the methods in vogue for holding a staff bymeans of wax. It is the common method employed by most watch repairers, the popular method so to speak. The method which I am now about todescribe may seem awkward at first to those who have not practiced it, but once you have fairly tried it, you will never be contented to work inany other way. The first requisite is a true taper chuck; and it is well to purchase anextra one to be used solely for this purpose, so that you will beprepared at all times for staff work. Select a good steel taper, andhaving placed your chuck in the lathe, see if your taper fits well byinserting it in the chuck while running slowly. If it fits well, it willbe marked almost throughout its length. Insert again in the chuck, andwith a few light taps of the hammer set it firmly in place, so that youknow that there is no danger of its working loose. The taper will thenproject about three-quarters of an inch from the face of the chuck. Bymeans of a sharp graver, make the face of the taper smooth and straight, and cut off the taper end. Now mark a point on the taper about one-fourthof an inch from the end, and proceed to turn down the diameter from thispoint to the end, leaving that portion of the taper about two-thirds ofits original diameter, and finish with a nice square shoulder. Now witha long-pointed sharp graver proceed to cut a nice V-shaped center with anangle of about 60°. When you have proceeded thus far you will find thatyou have an implement resembling that shown in Fig. 22. [Illustration: _Fig. 22. _] Care must be taken that the center is quite true, and that no projectionis left like that illustrated in Fig. 21, no matter how minute it may be. Now examine the center by the aid of a strong glass, and after you aresatisfied with its appearance proceed to test it. Take a large sized pinwith a good point, and placing the point in the center, maintain it inposition by pressing upon the head, and while revolving the lathe slowlyproceed to examine by means of your glass. If the center is a good onethere will be no perceptible vibration of the pin. Now procure a piece of small brass tubing with an internal diameter alittle less than that of the turned down portion of your taper. If thebrass tubing cannot be procured readily, you can substitute a piece ofbrass wire a little larger than the taper, and by means of a drill alittle smaller in diameter than the turned down portion you can readilymake a small tube about one-half inch long. Now by means of a broachproceed to open the tube to a point one-quarter inch from one end, andcarefully fit it on the turned down portion of your taper. After fittingtightly to the shoulder of the taper, proceed to turn out the other enduntil it will take in the hub of your staff easily and leave a littleroom to spare. Now turn your tube down in length until a little of thehub is exposed either way you put the staff in. Turn the outside of thetube smooth and to correspond with the outline of the taper, so you willhave a nice looking job when completed. Just below where the hub willcome drill a small hole in the tube and remove all burr, both inside andout, that may have been made in drilling, so that the shellac or wax willnot adhere to it. This little hole acts as an outlet for the air in thetube; and as the hot shellac enters at the end of the tube the air isexpelled through this vent. It also helps to hold the cement firmly inplace. Now try your staff in the tube again, and be sure that it is quitefree, and that you will be able to work on the portions of it above andbelow the hub, according as one end or the other is inserted. You are now ready to insert your staff and proceed with your work. Holdyour shellac in the flame of your lamp a moment until it is quite liquid, and then smear both the inside and outside of the tube with it. Heat theshell or tube gently by means of the lamp, keeping the lathe revolvingslowly all the while, and taking the staff in your tweezers proceed toinsert it carefully into the tube. Press firmly back, making sure that ithas reached the bottom of the V-shaped center. Pack the cement well inaround the staff, and while centering remove the lamp and allow thewhole to cool, keeping the whole revolving until quite cool. Now removethe superfluous cement by means of the graver, and heating the tube againslightly, proceed to center exactly by means of a pointed peg-wood, resting on your T rest to steady it. Turn slowly in the lathe and examinewith glass to see that it is quite true. Your completed instrument willresemble Fig. 23. [Illustration: _Fig. 23. _] The advantage of the device is that your center is always ready, and allyou have to do is to insert your chuck in the lathe, warm it, and you areready to insert your staff and proceed to work. As I said in the firstplace, it is well to employ a taper chuck exclusively for this work, andnot attempt to use it for any other, for if you try to remove your taperand replace it again, you will surely find that your work is out ofcenter, and you will be compelled to remove the brass shell and find anew center each time you use it. You can avoid all this trouble, however, by purchasing an extra chuck and devoting it exclusively to wax work. Ofcourse, the brass shell can be removed and placed in position againwithout in any way affecting the truth of the center, and any number, shape and size of shells can be made to fit the one taper, and theseshells will be found very useful for holding a variety of work, asidefrom balance staffs. CHAPTER VII. The two popular methods of holding a balance staff in wax have beendescribed and illustrated; the reader may take his choice. The turningand finishing of the other end of the staff is performed as previouslydescribed. That portion on which the hair-spring collet goes should beturned to nearly the proper size, making due allowance for the grindingand polishing that is to come. The balance seat should be slightlyundercut, so that the balance can be driven on tightly and all rivetingdispensed with. The size for the pivot can be determined from its jewel, as previously described. Finish the ends of the pivots flat and round thecorners off slightly; and right here comes a point worthy ofconsideration in all watch work. Leave no absolutely square corners inany of your work, but round them off very slightly. This may seem a verylittle thing, but it is one of the small things that go to make upfirst-class work. You can judge pretty accurately of a watchmaker by thecorners he leaves on his work, as well as by the appearance of hisgravers and screw-drivers. When your staff is completed and nicely polished, remove from the wax andboil in alcohol to clean, and when dried it is ready for the balance. Great care must be exercised in removing the balance from the old staff, especially if it be a compensation balance, that you do not distort itany way. If the balance has been riveted on extra care will have to beexercised. The riveting may be cut by means of a graver, or a hollowdrill made from Stubb's steel wire. The recess in the drill should justfit over the shoulder left for the reception of the hair-spring collet. The edge of the hollow drill has small teeth formed upon it similar to afine file, and will cut quite rapidly. After removing the balance, if it appears to be sprung in the arms, theresult of removal or previous bad treatment, proceed to bend themstraight, and then to true up the rim carefully, and stake on with a flatend punch. Now put on your roller and drive it down to the hub and seethat the roller is free from the fork. See that jewel pin reaches forkproperly and that the guard pin also reaches the roller. See that yourbalance is free from the plate and the bridge. If the balance is true andall right, you are ready to put on your hair-spring. See that it is inbeat. It is well to make a mark on the balance before taking off the oldstaff, showing positions of hair-spring stud and jewel pin. Three-quarter plate English lever and Swiss lever balance staffs differonly in detail, except that they are sprung under balances. The generaloperations for making, however, are similar to those described. I have not described the method of poising the balance for two reasons;first, the mere poising of a balance for a cheap movement is so simplethat it needs no explanation; and second, to describe the poising of thebalance of a fine watch is a lengthy task, and can hardly be includedunder the heading of staffing and pivoting. The ground has beenthoroughly and conscientiously covered by Mr. J. L. Finn, in a littlevolume entitled Poising the Balance, [A] and I would advise allwatchmakers, both young and old, to read what he has to say. Good pivoting is an art in itself, and although there are many whoundertake to do this work, there are but few who can pivot a staff insuch a manner that it will bear close inspection under the glass. Weoften hear watchmakers brag of the secrets they possess for hardeningpivot drills, but I fancy they would be somewhat surprised if theytraveled around a little, to find how many watchmakers harden theirdrills in exactly the same way that they do. The great secret, so-called, of making good drills, is to first secure good steel, and then use careto see that you do not burn it in the subsequent operations. The fewertimes the steel is heated the better. My experience teaches me that youcan do no better than to select some nice pieces of Stubb's steel foryour pivot drills. Many watchmakers make their drills from sewingneedles, say No. 3 or 4, sharps. The steel in these needles is usually ofgood quality, but the great drawback is that a drill made from a needlewill not resist any great pressure, and is liable to break just at thetime that you have arrived at the most important point. If your drill ismade from a piece of Stubb's steel wire, or an old French or Swissgraver, you not only know that the material in it is first-class, but youcan leave the base of the drill solid and substantial, with enough metalin it to resist considerable pressure. The part of the drill whichactually enters the pivot is very short, and the end can be turned downto the desired diameter. Turn or reduce your wire by means of a pivotfile so as to be smooth and conical, as shown at _A_, Fig. 24. Theconical form is given to the drill for exactly the same reason that it isgiven to the balance pivots, because it gives additional strength. Heatto a very pale red for about one-half inch from the end, and then spreadthe point, as shown at _B_, Fig. 24, by a slight blow of the hammer. Weare now ready to temper our drill, and we must exercise a little carethat the steel is not burnt and that the drill is not bent or warped whenhardening. The flame of the alcohol lamp should be reduced as small aspossible, or otherwise the steel may become overheated and lose all itsgood qualities. If needles are used for making drills there is a greatliability of their warping when hardening, but when a larger piece ofwire is used there is not much danger, if care is exercised inintroducing the drill that it goes into the compound straight and pointforemost. If a needle is used, it is well to construct a shield for it, to be used when heating and hardening. This shield can be made from asmall piece of metal tubing, broached out to fit loosely over the shankand point of the drill. The drill is introduced into this shield as shownin Fig. 25, and a little soap may be introduced into the end _a_ beforeplunging. Various hardening devices are used, but in my experiencebeeswax or sealing wax will be found as good as any. Heat the drill (orif a needle, the drill and shield both), to a pale red and plungestraight into the wax. In the latter case, where the shield is used, theshield, on striking the wax, will run up the shank of the drill, allowingthe point to pierce the wax. Some watchmakers introduce the extreme pointof the drill into mercury first and then plunge into the wax. Thishardens the extreme point of the drill very hard, so hard, in fact, thatit will penetrate the hardest steel, but care must be exercised with sucha drill because the mercury makes it not only very hard but very brittle. _C_, Fig. 24, shows a drill after it has been finished on the Arkansasstone. This shape of drill will withstand the pressure necessary to drillinto hard steel. Many watchmakers reduce the temper of every staff beforedrilling. This, I think, is quite unnecessary. There are very few casesin which it is necessary to reduce the temper of the staff, and even thenit should only be reduced as far as it is to be drilled, and then not inexcess of a good spring temper. [Illustration: _Fig. 24. _] [Illustration: _Fig. 25. _] The centering of a staff in wax has been thoroughly described and inpivoting the proceeding is the same as in staffing. After accuratelycentering your work, make a small cut in the center for the reception ofthe drill and make this mark deep enough to take the entire cutting headof the drill. Keep the drill firmly pressed into this center and kept wetconstantly with turpentine. Do not revolve the work all one way, but givethe lathe an alternating motion. At first give but a third or a halfrevolution each way, until the drill begins to bite into the staff, whenyou can then safely give it a full revolution each way. Care must beexercised, however, not to give the work too rapid a motion, for if youdo the friction is apt to draw down the temper of your drill. Manywatchmakers find that their drills cut well for a certain distance andthen refuse to work altogether, and one of the chief reasons is that theyare in too great a hurry with their drilling. If you find it absolutely necessary to reduce the hardness of your staffbefore drilling, do so by drilling a hole in the end of a small piece ofcopper wire that will just fit over the part to be softened, and applythe heat to this copper wire, say one-fourth of an inch from the staff. The heat will run down the copper wire and heat the staff just where youwish to draw the temper. Be careful and do not draw the temper too much, nor let it extend down the staff too far. The plug for the new pivot should be carefully made, perfectly round, with a very little taper, and should be draw-filed before being drivenin. Some workmen dip the plug in acid before driving in, as they declarethat the pivot is less liable to be loosened while turning, if sotreated. The acid simply rusts the pivot and the hole, but I cannot seethat this will hold it any more firmly in place while finishing. If thetaper is a gradual one and the pivot a good close fit, there will belittle danger of it loosening while dressing to shape. If too great ataper is given to the plug, there is danger of splitting the end of thestaff, and this involves the making of an entire new staff. The turning up of a new pivot does not differ in any way from theinstructions given for turning pivots on a new staff. With a little careboth in turning and finishing, a new pivot can be put in so nicely thatonly the initiated can tell it, and then only with the aid of a strongglass. In pivoting cylinders there is some danger of breaking them. To avoidthis, select a piece of joint wire, the opening of which is slightlylarger than the diameter of the cylinder at the lower end, and cut off apiece the length of the cylinder proper, leaving the pivot projecting. Now fill the cylinder with lathe wax, and while the wax is warm, slip onthe joint wire. You can now proceed to true up the pivot in the usualmanner, and when the wax is quite cold, proceed to turn and polish thepivot before removing from the lathe. If the joint wire is properlycemented on the cylinder, it is almost impossible to break it. After allthe work is done, the wax can be dissolved in alcohol. In pivotingpinions to cylinder escape-wheels and third wheels, it is not necessaryto remove the wheels, but great care should be used in handling. In thelatter case use plenty of wax. Do all your centering by the outside ofthe pinion. Perfect centering and sharp tools are requisite to goodpivoting. Do not try to rush your work, especially while drilling. Proceed deliberately with your work and aim to restore the watch to thecondition it was in originally, and you will find staffing and pivotingis not half as hard as some workmen would have you believe. [Footnote A: POISING THE BALANCE, by J. L. Finn, Geo. K. Hazlitt & Co. , publishers, Chicago. ]