One of the hard parts of preparing the flywheel was done a long time ago, before cutting it round. The wheel rotates on a 1/2 inch axle. I drilled the center hole and then used that hole as the pivot point for cutting the perimeter on the band saw. Nice! Guaranteed center for the axle.
Here, we see the axle mounted. I used the ever popular plumbing flange on both sides of the wheel. The purpose of this flange is to connect the wheel mass to the axle. That is done with a simple 9/64″ hole drilled through the axle and a common “8 penny” nail through a pair of holes already in the flange. Simple. Snug. Done! (Oh well, almost. The axle will be cut to length later.)
Yes, there’s a matching flange on the other side of the wheel. No pin through it; all we need is one. The real purpose of that flange is to provide a bearing surface for the washers that will keep the wheel centered between the uprights. You’ll see those later.