My decision to procrastinate with respect to the steam passages has worked, I think. Several suggestions have come in, and I am intending to go with the one from Stuart. And that is to angle the steam passages, which lengthens one on which I can use a larger diameter milling cutter, and to shorten the one under the steam port. See the red lines for the proposed changes.
Red line plan alteration in the high pressure steam lines. The other cylinder plans will be altered also.
While waiting for a light bulb to switch on regarding the dark places, I have not been idle.
I moved on to a part of the triple expansion steam engine build which I expect to be easier. And that is the condenser unit.
The condenser is the box shaped protuberance attached to the columns. I believe that its function is to convert the last dregs of steam, after driving the 3 pistons in succession, into water, for re-use in the boiler.
These are the components, machined and ready for assembly.
The condenser components. There are 28 tubes, to be soldered into the holey brass plates.
The holes in the end plates have 0.5mm of material between them. Tricky drilling, but a breeze for the CNC mill.
CNC drilling the end plates. Centre drilling initially. The 112 operations proceeded perfectly. Did I say before that I love CNC.
End plate holes. No breakthroughs, despite only 0.5mm between holes.
An end cover after machining. The bosses and holes were CNC’d.