With the four Locking Sleeves for the Inlet Valve Caps made and out of the way, the next job is to make the "Dogs" also known as "Valve Cap Bayonet Sleeves" to hold them in place. These are made of cast iron. A 2" length of cast iron was was cut off from a 3" diameter cast iron bar, put in the lathe and the outside machining completed. A 3/4" diameter hole was then drilled into it. Ready for the boring tool, so that it could then be bored out ready for threading 2" x 11 to suit the Locking Sleeve.
The threading was mainly completed with an internal screw-cutting tool and finished off with a Thread Chaser.
The Locking Sleeves were tried in the freshly cut threads to make sure they fitted, and then the "Dog" was parted off from the holding piece in the lathe.
We will get the other three to this same stage and then cut the superfluous parts of the flanges away, just leaving the bayonet parts which will hold them in position.