Figs. 401, 402.
These two castings, 401 and 402, are bolted together with two bolts and nuts through the holes 5 and 6, as shown in [Fig. 400]. Fig. 403, is a back view of the additions, showing the cog wheels and their connections, also the brass bearings for the lower mandrel required when allowed to traverse. This was a solid piece of brass with a hole bored out and ground to fit the mandrel. It was then drilled the whole depth in two places, for two steel steady pins, b, c, made to fit quite tight, and at both ends for bolts and nuts, a, d, afterwards sawn in two with the circular saw, and when put together and two holes drilled through the thickness for fixing it was put in its place, adjusted, and re-ground on. The holes for fixing were very carefully continued through the cast iron upright, and the whole was finally fixed with two screw bolts and nuts.
[Fig. 404], is a front view, showing the eccentric chuck, R, on the upper mandrel, the slide of which when used is connected with the bracket in the wall, [Fig. 406], causing the whole apparatus to oscillate in proportion to the eccentricity of the chuck on its centres one of which is marked at S. The chuck has a circular movement for laying the waves in any position with one another, but which also is effected by another plan to be presently described. The whole poppet with its fittings is hung on centres similar to the rose engine described in this work. The top part of the bed T removes, and the two screws, one shown at V, are taken out to allow the oscillation. The large cog wheel has 192 teeth.
Figs. 403, 404, 405, 406.
The whole of the additions to my headstock were all of my own fitting up. The brass cog wheels were bored out and ground to fit an arbor made on purpose, exactly corresponding in diameter with the ends of the spindles so that they might fit indiscriminately on either spindle. When turned up, the teeth were cut with a circular cutter, which I made just of the exact shape and thickness required for the space between the teeth. The cutter was turned of steel; then wrapped in leather and enclosed in sheet iron. It was then put in the fire, made red hot, and left for the fire to go out, the next day being soft, it was cut with sharp chisels into a circular file and hardened, and with it in the cutter frame the teeth of the wheels were cut. The central boss of each wheel has a notch cut across the face to receive a pin in the arbor and in the spindles, which prevents the wheels from turning round on the latter when screwed up.
This rose engine works beautifully smooth and easy, and ornamentation can be done with it with greater rapidity than with the ordinary engine, by arranging the connecting wheels so that the upper mandrel makes so many waves and one-half, one-third, one-fourth, one-fifth, one-sixth, or any other part of a wave, on each revolution of the lower mandrel, because then it requires certain revolutions of the lower mandrel before the tool comes into the same cut again—say, for instance, it makes 45/6 waves on each revolution, then it takes 29 revolutions of the upper mandrel to complete the pattern, whereby certain patterns are completed without stopping the lathe, which is an advantage that the rose engine proper does not possess. Another great advantage is, that the waves can be either flat, sharp, or intermediate, as required for large or small work, by altering the eccentric chuck on the upper mandrel.
I give a few specimens, not for the beauty of design, but to illustrate the working of the engine. The centre of [Fig. 407] is performed by having a wheel of 80 teeth on the upper mandrel, connected with one of 25 teeth on the intermediate spindle, which has another of 50 teeth connected with the large wheel of 192 teeth on the lower mandrel; thus,
| 80 | ||
| 25 | 50 | =11/5 |
| 190 |