Les Kerr continues the construction of the parts for the steam engine. Two rotary valve centres are required (fig 27). The inside is hollowed out to reduce the weight of the valve centre, making it easier to rotate. I used a piece of 1/2in. dia. by 52mm brass for this part. I drilled the 4mm holes first, then turned down the 6mm dia. section. The remaining 19mm length was reduced to 0.38 dia. (0.005in. oversize). Transfer the chuck with job to the dividing head which was previously mounted vertically on the mill.
展开▼
