Watch Case Tool
American Watchmaker and Jeweler (1892)
The Hopkins' patent watch case tool is designed for the two-fold purpose of easing a case when it opens too hard, and for making one stay shut when it opens too easy. It is illustrated in Fig. 312. The part D is intended only for use when the spring catch of a hunting case has worn the case so that it will not stay shut. For making a back case stay shut when it opens too easily, use the cutting tooth B, in the following manner: Rest the beveled edge of the tool from A to C, down level on the ledge against which the dome or back case closes, as represented in the illustration, taking care to keep the end A as well as the tooth B down level on the ledge, and inward against the part to be re-undercut, in which position, with the end D resting in the hollow of your right hand, back of the little finger, and with your thumb resting on the inner cap to steady your hand, hold the tool thus quite still, and with your left hand give a circular movement to the watch, crowding the part to be under cut against the tooth B, that is, instead of shoving the tool forward to produce the cutting, hold the tool still, and crowd the part of the case to be cut against it as described. By thus renewing the under cut of the catch edge, even a badly worn case may be made to shut and stay shut nicely. For easing the cap or the back case of a watch when it opens too hard, rest the end A, of the tool, down on the inside of the dome, with the handle inclining backward at an angle of about 45 deg., and with one of the sharp edges extending from A to C, brought to bear against the snap edge that requires to be eased, in such a way that it will give a shaving (not a scraping) cut; carefully shave off the edge, thus, to the extent required. In this way even the most delicate case may be eased without the slightest marring or injury to it. In case of roughness of the snap edge, burnish it carefully with the back of the tool; or rubbing a bit of beeswax around the edge will often be found of service in cases of this kind.
What Has Changed in the Last Century
When the American Watchmaker and Jeweler described the Hopkins' patent tool in 1892, nearly every watch was a pocket watch with a hinged hunting cover or a snap-on back, and a case that would not stay shut was an everyday bench job. Wristwatches overtook pocket watches after the First World War, and by the 1930s manufacturers were moving to screwed-down and gasketed backs sealed against water and dust, which are opened with case wrenches and press tools rather than re-undercut with a cutting tooth. The technique itself has not been disproved: restorers of antique pocket watches still ease a tight snap edge by shaving rather than scraping, and still burnish or wax a rough one. What has gone is the trade that needed the tool daily; Hopkins' tools now turn up mainly in collections of old watchmaking equipment.
Written for this edition, 2026.