From Horology magazine, November, 1937
Tightening Cannon Pinions
Answer: The use of the triangular punch for tightening a cannon pinion cannot be too strongly condemned. Aside from the mutilation of the pinion the friction thus created is never lasting or smooth. Even if these three nicks should survive long enough to be pushed on the post, the first few times the hands are set they will wear off. For tightening an ordinary cannon pinion there is nothing better than the cutting plier illustrated in Figure 2. The edges of this plier are very thin enabling one to get into the narrow groove of a small pinion without burring the square sides of the groove. Of no less importance is the adjustable stop screw, an absolute assurance that the pinion will not be cut in two. In addition one should always insert a round steel broach in the pinion while tightening it.