US2975567A - Method for polishing the balance pivots of a watch - Google Patents

Description

March 21, 1961 H. B. LITTLE 2,975,567

METHOD FOR POLISHING THE BALANCE PIVOTS OF A WATCH Filed May 4, 1960 2 Sheets-Sheet 1 INVENTOR. HUGH. B. LITTLE.

MAHONEY MlLfiiAR BO TTYS. BY.

2,975,567 METHOD FOR POLISHING THE BALANCE PIVOTS OF A WATCH Filed May 4, 1960 H. B. LITTLE March 21, 1961 2 Sheets-Sheet 2 INVENTOR. HUGH. B. LITTLE BY MAHONY MILLER & RAMBO TWs.

METHGD FOR PGLISHING THE BALANCE PIVOTS OF A WATCH Hugh B. Little, Litties Watch Service, Box 465, Logan, Dhio Filed May 4, me, Set. N5. zasns 6 Claims. c1. 51-281) My invention relates to a method for polishing the balance pivots of a watch. It has to do, more particularly, with a system for use in cleaning and polishing the pivots or ends of the shaft or balance staff of a watch.

As is well known to jewelers or watch repairmen, the polishing of the pivots on the ends of a watch balance staff is very difficult. These pivots range in size from approximately .06 mm. to .14 mm., the .06 mm. size being smaller than a human hair. In order for a watch to run properly and keep time, the balance pivots must have a high polish and be properly oiled. At present, it takes a skilled watch repairman a considerable length of time to polish the balance pivots due to the time necessary to set up the tools now commonly used for this purpose and the difficulty of positioning the pivots relative to the tools and properly holding the pivots in such a manner as to prevent damage thereto. The hair spring and/or roller table must, with present polishing methods, be removed from the balance assembly before polishing the pivots. All of the prior art polishing methods are based on the same principle. They spin the balance staff and polish the pivots on the shaft by putting polish on a piece of steel or wood and holding it against the rotating shaft. Great care and skill must be used in the polishing operation to secure a high polish and to keep from bending, breaking, burning or otherwise damaging the pivot.

It is the main object of my invention to provide a polishing method and system for use in polishing the pivots of a watch balance staff assembly which can be used by a relatively unskilled person to quickly and effectively polish the pivots.

It is another object of my invention to provide a device for polishing watch balance pivots which can be used on the balance staff assembly without removing the hairspring and/ or roller table therefrom.

A further object of my invention is to provide a polishing device for balance staff pivots which will effectively polish the pivots without danger of damaging the pivots in any way.

Various other objects will be apparent.

In the accompanying drawings, I have illustrated my polishing device and the method by which it is used in polishing the balance pivots of a watch.

In these drawings:

Figure 1 is a side elevational view, partly broken away, of the polishing device.

Figure 2 is an isometric View showing a strip used in making the polishing loop.

Figure 3 is a transverse sectional View taken along line 33 of Figure 2.

Figure 4 is a view illustrating the twisting of the ends of the strip preparatory to forming the polishing loop.

Figure 5 shows the loop shaped preparatory to inserting in a holding chuck.

Figure 6 shows the loop inserted in the chuck and a tool being used to shape its exposed or projecting end.

2,975,567 Patented Mar. 21, 1961 Figure 7 is a side elevational view, partly broken away, showing a balance pivot in cooperative relationship with the polishing loop.

Figure 8 is an enlarged axial sectional view through the polishing loop and holding chuck showing the action of the loop on the end of the pivot.

With reference to the drawings, in performing my method, I employ a device which includes a chuck 20 in which the polishing loop 21 is mounted. This chuck 20 is carried by a shaft 22 which is suitably rotated. For example, the shaft may be driven by any suitable driving motor 23, either mechanical or electrical. The loop 21 has an outer convex surface 25 exposed at the outer end of the chuck 20. It will be noted from Figure 6 that the chuck 26 has a loop-receiving socket 26 which is tapered or belled outwardly.

An important feature of this invention is the polishing loop 21. It consists of plastic or deformable rubber material which is relatively soft and which is impregnated with a rouge or other polish material. In forming this loop, a strip 27 of the rubber material is cut from a sheet which has been previously impregnated with fine polish material 28. This rubber may be of the type commonly known as cushion gum which is a soft, relatively sticky, unvulcanized rubber, and which can be deformed and will tend to stay in deformed condition. The strip is narrow and elongated as shown in Figure 2.

The next step in preparing the loop is to twist the ends of the strip as indicated in Figure 4. Then. the strip with the twisted ends is folded back on itself to form a loop 21 as indicated in Figure 5. This loop 21 will have a space or slot 30 extending longitudinally thereof between the opposite sides or folds of the loop. The adjacent ends of the loop may be twisted together to hold it in loop fdrm as indicated in Figure 5.

The loop so formed is then forced inwardly into the tapered socket 26 as shown in Figure 6. It will be deformed and compressed during this forcing action which will narrow the slot 30. The loop will now be held in the socket by means of friction. With the chuck 2.0 rotating, the outer end of the loop may be formed to provide a convex or spherical surface 25. A suitable forming tool is indicated at 31 in Figure 6 and is provided with a concave socket 32 at its outer end. If this tool is pressed against the projecting end of the loop as it is rotated, the convex surface 25 will be formed. Thus, as shown in Figures 1, 7 and 8, the polishing loop 21 will now be in proper condition to function as the polishing member. It may be treated from time-to-time with the tool to restore the convex spherical surface.

The balance assembly to be polished is indicated in Figures 1 and 7 and comprises the balance wheel 40, which has the balance staff 41 projecting from opposite sides thereof with the opposed pivots or shafts 42 and 43. At one side of the wheel 40 is the roller table 44 and at the other side is the hairspring 45. Neither of these units need be removed during the polishing operation.

In performing the polishing operation, the chuck 20 is driven at such a speed to rotate the loop 21 at a suitable speed. The end of the shaft to be polished, for example, the end 43, is first disposed in contact with the spherical surface 25. The rotating spherical surface will center the rounded end of the shaft with the axis of the chuck and the loop 21. Then the shaft end 43 is forced through the outer or closed end of the loop into the inner slot 36 as shown in Figure 8. After piercing the closed end of the loop, the staff or assembly 41 is shifted to an angle relative to the axis of the chuck 20 and the loop 21 as shown in Figure 8, the flexible nature of the rubber in the loop permitting this. If held at such an angle, the opposite inner flat surfaces 46 and 47 of the loop 21 will alternately contact the ends of the pivot 43 during rotation of the loop. This can be noted from a clicking or rubbing action which occurs at intervals when the end of the shaft is held within the loop in the manner-indicated. This rubbing on polishing action created in this manner will efiectively polish the pivot end without damaging the pivot. After a short interval, the shaft will be shifted to a different angle to polish the other side of the rounded end. This shifting to a different angle is indicated by broken lines in Figure 8.

Thus, itwill be noted that the extreme end of the pivot will be etfectively polished by the rubbing action of the soft rubber impregnated with the polish or rouge. Furthermore, it will be noted from Figure 7 that during this polishing operation it is not necessary to remove either the roller table 44 or the hairspring 45. The balance pivot initially will be automatically centered relative to the loop 21 and when forced through the material of the loop will be held in centered position. Therefore, it is not necessary for a skilled operator to perform the polishing operation. The polishing apparatus is always set up ready to use except that it may be desirable to restore the convex surface 25 of the loop 21 at intervals by means of the tool 31. There is no danger of bending or otherwise distorting, breaking, burning or otherwise damaging the end of the pivot. The polishing loop may be removed and replaced readily as necessary.

According to the provisions of the patent statutes, the principles of this invention have been explained and have been illustrated and described in what is now considered to represent the best embodiment. However, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated as described.

Having thus described my invention, what I claim is:

1. The method of polishing the pivot of the balance shaft of a watch which comprises impregnating a strip of material with a polishing material, forming the strip into a loop, projecting the pivot end of the balance shaft through the closed end of the loop at the axis of the loop and holding the shaft at an angle with the end of the pivot in contact with the inner surface of one side of the loop, and rotating the loop about its axis.

2. The method of claim 1 in which the angularity of the shaft is reversed after polishing for an interval in the first indicated angular position.

3. The method ofclaim 1 in which the strip of material is plastic rubber that is impregnated with a polish ing rouge.

4. The method of claim 3 in which the closed end of the loop is exposed and is of spherical form.

5. The method of polishing the pivot of the balance shaft of a watch which comprises forming a strip of polishing material into loop form and projecting the pivot end of the balance shaft through the closed end of the loop and at the axis of the loop, holding the shaft at an angle with the end of the pivot in the slot between the sides of the loop and in position to be contacted by said sides, and rotating the loop about its axis.

6. The method of claim 5 in which the closed end of the loop is exposed and is of spherical form.

References Cited in the file of this patent UNITED STATES PATENTS 596,014 Condon et al. Dec. 21, 1897 2,519,556 Fish Aug. 22, 1950

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