Fig. 68.
It may also answer to stretch the wheel, if it is thick enough to be sufficiently increased in size. A cutter should then be selected for rounding-up which will allow the full width to the tooth as at p; but if it is not possible to enlarge the wheel enough, a little of the width of the teeth may be taken off, as is seen at h, which will diminish the butting with the leaf r.
Too great depthing, [Fig. 69], can generally be recognized by the lack of drop. When the teeth of the wheel are narrow, the drop may appear to be sufficient. When the train is put in action the depthing that is too great produces scratching or butting and the ’scape wheel trembles. This results from the fact that the points of the teeth of the wheel touch the core of the pinion and cause it to butt against the leaf following the one engaged, as is visible at r in [Fig. 69]. It should be noticed that in this figure the pitch circles mm and kk overlap each other, instead of being tangential.
Fig. 69.
Fig. 70.