Stuart No 1 - Top Cylinder Cover

This component had no critical dimensions although to look right it needed to have accurately spaced holes.


First the end cover was mounted in the 3-jaw chuck, with the spigot facing outwards. The spigot was skimmed until it was round. This was done to ensure that the spigot was central when referenced from the outside edge of the casting.


The cover was reversed in the chuck and held by the spigot.

First the shoulder to locate the cover on the cylinder was formed so that the finished cylinder was a close fit.

Combinations of tooling were used to make the rest of the profile given by the drawing on the underside of the top cover.

Both end covers were made with an external diameter 1mm oversize, so that they would fit flush with the cylinder lagging.


The casting was removed from the chuck and the spigot was sawn off. Then it was placed back in the chuck again to machine the top surface. Some paper was used with each of the jaws to avoid marking the edge of the cover.

The dome was formed 'by eye' using a turning tool, file and was finished with some emery cloth.

The screw locations were marked on this side by making a small dent with a lathe tool at the correct PCD. This initial mark was enlarged with a centre punch before centre drilling, and drilling on the drill press.


To make 6 evenly spaced holes a small spirit level (cut from an old wood working tool) was placed on each of the chuck jaws (back and front) to give 6 equally spaced marks.

This technique is not 100% accurate, but can give acceptable results if the mating component is drilled to suit.













Stuart 1 Index