Connection area to seam passage of cylinder was recessed.
Feeding depth of steam passage was checked.
The steam passage was drilled.
Last part was hand-drilled.
Finished steam passage.
I made a jig for drilling the mounting holes of the drill cover. I bored the centre hole before, but this time I cut it by 12mm slot drill. However cut a hole on MS with this size of slot drill seemed exceeding the capacity of my mill and the hole was made bit bigger.