The original plans for this next item called for a miniature grub screw to fix it to the valve spindle.  From the outset, I thought that this method would not work for me. The revised plans changed to fixing the arm by either Loctite or a pin.   What I decided was clamping it to the spindle.

The only thing I am going to use from the plans is the distance of 0.313" between both holes. I used stainless for these parts and here they are with what I managed to do till now.

The miniature hardware came from France and I made two temporary spanners for them. The bottom one is a 1.4mm bolt and the top one for comparison is a 2mm bolt. Really small. I have to be careful not to lose them! 

I managed to find a 3mm and also a 4mm grub screw. The socket of the 4mm grub screw fitted perfectly in the hex head of the 1.4mm bolt. So I quickly made a box spanner using the grub screw and a piece of 5mm mild steel.

I also drilled the first 1.4mm hole and fitted the 1.4mm hardware to see how it will look. That's when I realized that across flat size of the nut is larger than the bolt. It is 3mm AF. No problem, I have a spanner that size, or so I thought.  Could not find it.  Oh well I just had to make myself one.

All the parts for the Corliss finally finished!! The final four arms took longer than anticipated to finish but I am happy to say that they are out of the way.

The next operation on these parts was to cut a slit at the back. They were ganged together and using a 0.25mm slitting saw the slit was slowly done. I did not think I would be able to do it but I guess beginner's luck prevailed on that day.

A trial fit to see if it would actually clamp to the valve spindle.  Good thing I did that homemade box spanner and open ended spanner!  Made life so much easier.

No chance of the arm getting loose on the valve spindle. The excess material at the front of the arm was removed with a hacksaw and using the same setup for the connecting rods, the front part was rounded off.

A little fettling and polishing later, and the arms fitted to see how they look. All that remains now is to assemble it all, check for binding and put some air into it. 

After fiddling with the Corliss, I decided to take the plunge and put some air into it. I found some spare time to set the valves. They are really fiddly but I blessed my stars that I had made that miniature box spanner and open ended spanner.

Then I put some air in it. I did not even make an air adaptor for it and held the inlet pipe manually. Set it to 20 psi and applied air It shot off and as I was not expecting anything to happen, it gave me a fright and let off everything. It would turn with less than 5 psi.

Prepped the parts that were ready to be painted by cleaning, masking and priming them. Started with re-assembling the front part of the cylinder. Fitted the valve bonnets (with gaskets) and the valve disc hub.

The Corliss was reassembled and running even better than before with a much lower pressure. The pressure gauge is not even moving. I used some of the gaskets I made on the parts that I think will not be disassembled again. I also changed the timing of the valves to their correct position. Previously at TDC and BTC they were set to just fully open but now they are set to just fully closed.

I decided to make an exhaust pipe for the exhaust cover plate. Nothing special.  Just a brass flange and a brass pipe. As the pipe will be passing through the base and to make life easier during assembly and disassembly, I threaded one end of the pipe so I can screw it into the flange.

Attached some extra detail to the flywheel to simulate a spilt flywheel.

Drawings here

Part 21 here  Part 23 here