The Watch & Clock Makers' Handbook, Dictionary and Guide by Frederick James Britten

Author:Frederick James Britten
Language: eng
Format: epub, pdf
Publisher: Spon
Published: 1896-03-25T05:00:00+00:00

Fig. 4.

l"i.^^- 5-

at an angle of al^out 45~; hold the steel in the vice while doing so, and continue the slope as in Fig. 6 up to the pivot, taking care not to nick the latter at the root. Reverse the steel in the vice, and file the front sloi)e at the same angle as the back (Fig. 6), shortening the base of the hook in the direction of the dottedliue until it is right length. This will be determined by placing the back slope of the hook on the outer slope of the barrel hole, and trying it carefully and frequently until the front slope will pass through. The hook thus formed should pass freely through the hole, fitting it closely at the sides and ends, for more than the height eventually required. The pivot is now to be shortened to about twice the thickness of the spring and riveted slightly, the inner vside of the hole having previously been chamfered to receive the rivet, which must project as little as possible above the spring. The hook is now to be cut off the steel as indicated by the dotted line in Fig. 6, and filed to right height. To ascertain the right height pass the hook through the hole in the reverse direction to that above-mentioned, i.e., with theyr^w/slope of the hook towards the 02c^er slope of the hole, and lower it until its height barely equals the thickness of the barrel rim. Polish the

hook and before winding in see that the spring is perfectly flat, and that its circular form is not disturbed at the hook. If properly made the hook will slip freely into the hole, and the outer coil of the spring will lie close to the inner circumference of the barrel. The outside of the barrel should never be filed, neither should the hook be tampered with after it is rivetted on the spring. If these directions are carefully followed, but little practice will be needed to ensure good fits, and to make the operation of hooking the mainspring a simple one indeed.

The advantage generally claimed for the hook riveted to the spring over the eye attached to a stud in the barrel, is that the former being a rigid attachment keeps the coils of the spring equally diffused when under tension, instead of alio wing the turns to go over in a mass to the point of least resistance. But the spring must not be left perfectly hard at the rivet or it will break, and in many instances it is found that when the spring is wound it is bent at the rivet, forming an elbow. The advantage of the rigid attachment is then lost, and the spring goes over at once to the point of least resistance. Sometimes the end of the spring beyond the hook is thinned, and also filed to a point, but the chance of the spring breaking across the rivet is thereby much increased without serving any good purpose.

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