Well I'd started two elbow engines No 1 has resided on the desk where I absentmindedly give it a turn now and then, as for No 2 that was never finished off, and its spent the time on the back shelf of my shop, but I have been on the look out for material to make the flywheel from, I've pick up quite a few short pieces of brass tube about 1" long and 3 to 4 " dia and some 1/4" ally plate, so its time for No 2 to be finished off I'm planning to add a bit of novelty to this one:- so here we go.
First job clean fly wheel rim and bore.

Bore cleaned to leave a 1mm step for the hub to but against.
The hub is made from 1/4 " plate rough cut to shape with a centre roughly in the middle then some masking tape stuck on the back for friction turning.

Grip a stub of bar flush with the jaws of the chuck.

Trap the piece of plate between the running centre and the chuck and with light cuts skim up the OD to give a nice neat fit in the rim.

Now I'm going to cut the spokes in the hub using the RT and and the PCD feature of the mill DRO.
First stub of bar in the chuck to lift the hub clear of the chuck jaws.

Grip the hub in the chuck with the RT still lose on the table centre the RT with the quill by holding a centre tight into the centre in the hub, then tighten the RT down.

I drew out the the hub in cad and put a few critical dimensions on the drawing to guide me. Then using a combination of the RT and the PCD feature of the DRO drill corner holes 5 mm.

Then using a 5mm slot drill joined the holes up.

Then repeat for the inside.

Then join the two parts up

And thats it spokes cut in the hub they need a bit of a tidy up and the bore opening out for the cylinders but that jobs for another day.

This is what it looks like in the rim with the cad drawing.
Have fun
Stew