As the inlet and exhaust valves are on the side of this engine the actual cylinder head was quite an easy job. The odd legs were used to swing a few arcs to get an average centre position and the casting then held in the 4-jaw to get this running true.
And the spigot turned to a nice fit in the top of the cylinder.
It was then just a case of reversing the part and facing off down size then turning the recess in the top. Final job was to drill the five 2BA clearance holes.
The hopper is quite a lump, weighing it at 2.5kg and measuring 5.5" diameter. To make sure I got the top and bottom holes in line I first machined a disc to fit snugly in the top opening and clocked that in on the mill table.
I could then slip the hopper over this disc and using a small height gauge get the central bead as horizontal as possible with the aid of some feeler gauges as packing. With a clamping bar inside it was then just a case of using the boring head to open out to the required 2.5". I do like these indexable bars from Glanze, they seem to work very well in all metals and will cut down to a 12mm dia hole.
I then skimmed the bottom surface back to the required size.
Before drilling another four 2BA clearance holes for the studs.
Next it was over to the lathe so that the recessed hole for for the lid could be done, as its a fair size casting and the cut some 5" from the chuck I added a length of studding through the spindle just to be sure it would stay put.
The hopper lid was not the easiest to hold either so I put a bit of brass bar in the tailstock chuck just to make sure it would not work its way forwards while the spigot was turned.
It was then easy enough to hold by this spigot while the rim was finished.
