The Modern Clock / A Study of Time Keeping Mechanism; Its Construction, Regulation and Repair

by Ward L. Goodrich

All springs should be cleaned by soaking in benzine or gasoline and rubbing with a rag until all the gum is off them before they are oiled. Heavy springs may be wiped by wrapping one or two turns of a rag around them and pushing it around the coils. The spring should be well cleaned and dried before oiling. A quick way of cleaning is to wind the springs clear up; stick a peg in the escape wheel; remove the pallet fork; plunge the whole movement into a pail of gasoline large enough to cover it; let it stand until the gasoline has soaked into the barrels; remove the peg and let the trains run down. The coils of the spring will scrub each other in unwinding; the pivots will clean the pivot holes and the teeth of wheels and pinions will clean each other. Then take the clock apart for repairs. Springs which are not in barrels should be wound up and spring clamps put on them before taking down the clock. About six sizes of these clamps (from 2½ inches to ¾ inch) are sufficient for ordinary work.

Rancid oil is also the cause of many “come-backs.” Workmen will buy a large bottle of good oil and leave it standing uncorked, or in the sun, or too near a stove in winter time, until it spoils. Used in this condition it will dry or gum in a month or two and the clock comes back, if the owner is particular; if not, he simply tells his friends that you can’t fix a clock and they had better go elsewhere with their watches.

For clock mainsprings, clock oil, such as you buy from material dealers, is recommended provided it is intended for French mainsprings. If the lubricant is needed for coarse American springs, mix some vaseline with refined benzine and put it on liberally. The benzine will dissolve the vaseline and will help to convey the lubricant all over the spring, leaving no part untouched. The liquid will then evaporate, leaving a thin coating of vaseline on the spring.

It is best to let springs down, with a key made for the purpose. It is a key with a large, round, wooden handle, which fills the hand of the watchmaker when he grasps it. Placing the key on the arbor square, with the movement held securely in a vise, wind the spring until you can release the click of the ratchet with a screwdriver, wire or other tool; hold the click free of the ratchet and let the handle of the key turn slowly round in the hand until the spring is down. Be careful not to release the pressure on the key too much, or it will get away from you if the spring is strong, and will damage the movement. This is why the handle is made so large, so that you can hold a strong spring.

It is of great importance, if we wish to avoid variable coil friction, that the spring should wind, from the very starting, concentrically; i. e., that the coils should commence to wind in regular spirals, equidistant from each other, around the arbor. In very many cases we find, when we commence to wind a spring, that the innermost coil bulges out on one side, causing, from the very beginning, a greater friction of the coils on that side, the outer ones pressing hard against it as you continue to wind, while on the outer side of the arbor they are separated from each other by quite a little space between them, and that this bulge in the first coil is overcome and becomes concentric to the arbor only after the spring is more than half way wound up. This necessarily produces greater and more variable coil friction. When a spring is put into the barrel the innermost coil should come to the center around the arbor by a gradual sweep, starting from at least one turn around away from the other coils. Instead of that, we more often find it laying close to the outer coils to the very end, and ending abruptly in the curl in the soft end that is to be next the arbor. When this is the case in a spring of uniform thickness throughout, it is mainly due to the manner of first winding it from its straight into a spiral form. To obviate it, I generally wind the first coils, say two or three, on a center in the winder, a trifle smaller than the regular one, which is to be of the same diameter of the arbor center in the barrel. You will find that the substitution of the regular center, afterwards, will not undo the extra bending thus produced on the inner coils, and that the spring will abut by a more gradual sweep at the center, and wind more concentrically.

The form of spring formerly used with a fusee in English carriage clocks and marine chronometers is a spring tapering slightly in thickness from the inner end for a distance of two full coils, the thickness increasing as we move away from the end, then continuing of uniform thickness until within about a coil and a half from the other end, when it again increases in thickness by a gradual taper. The increase in the thickness towards the outer end will cause it to cling more firmly to the wall of the barrel. The best substitute for this taper on the outside is a brace added to some of the springs immediately back of the hole. With this brace, and the core of the winding arbor cut spirally, excellent results are obtained with a spring of uniform thickness throughout its entire length. Something, too, can be done to improve the action of a spring that has no brace, by hooking it properly to the barrel. The hole in the spring on the outside should never be made close to the end; on the contrary, there should be from a half to three-quarters of an inch left beyond the hole. This end portion will act as a brace.

When the spring is down, the innermost coil of it should form a gradual spiral curve towards the center, so as to meet the arbor without forcing it to one side or the other. This curve can be improved upon, if not correct, with suitably shaped pliers; or it can be approximated by winding the innermost coils first on an arbor a little smaller in diameter than the barrel arbor itself.

Another and very important factor in the development of the force of the spring is the proper length and thickness of it. For any diameter of barrel there is but one length and one thickness of spring that will give the maximum number of turns to wind. This is conditioned by the fact that the volume which the spring occupies when it is down must not be greater nor less than the volume of the empty space around the arbor into which it is to be wound, so that the outermost coil of the spring when fully wound will occupy the same place which the innermost occupies when it is down. In a barrel, the diameter of whose arbor is one-third that of the barrel, the condition is fulfilled when the measure across the coils of the spring as it lays against the wall of the barrel, is 0.39 of the empty space, or, taking the diameter of the barrel as a comparison, 0.123 of the latter; in other words, nearly one-eighth of the diameter of the barrel. This is the width that will give the greatest number of turns to wind, whatever may be the length or thickness of any spring. If now we desire a spring to wind a given number of turns, there is but one thickness and one length of it that will permit it to do so. The thickness remaining the same, if we make the spring longer or shorter, we reduce the number of turns it will wind; more rapidly by making it shorter, less so by making it longer. It is therefore not only useless, but detrimental, to put into a barrel a greater number of coils, or turns, than are necessary, not only because it will reduce the number of turns the barrel will wind, but it will produce greater coil friction by filling up the space with more coils than are necessary.

A mainspring in the act of uncoiling in its barrel always gives a number of turns equal to the difference between the number of coils in the up and the down positions. Thus, if 17 be the number of coils when the spring is run down, and 25 the number when against the arbor, the number of turns in uncoiling will be 8, or the difference between 17 and 25.

The cause of breakage is usually, that the inner coils are put to the greatest strain, and then the slightest flaw in the steel, a speck of rust, grooves cut in the edges of the spring by allowing a screwdriver to slip over them, or an unequal effect of change of temperature, causes the fracture, and leaves the spring free to uncoil itself with very great rapidity.