A bit of an update on Agnes. I have been "slowly but surely" making some progress on the flywheel.
This photo shows the full size flywheel being re-erected at it's new location in Markham Grange steam museum, as can be seen the hub is a substantial casting with eight spokes being attached using wedges to pull them into the hub.
And the flywheel fully assembled, showing how it is also wedged onto the crankshaft.
My model will have dummy wedges, the hub will be secured using parallel keys onto four flats on the shaft, but there will be some socket grub screws fitted down under the roots of the spokes to hold everything in place.
The spokes will then be pulled into the hub using socket head screws down the centre of each spoke. Once the shaft, hub & spokes are fully assembled, the eight segments of rim can be fitted and machined in situ, then lastly the eight segments of the internal barring gear will be fitted and the teeth machined as a final operation.
The first challenge is to make a hub out of bar material so that it looks like a casting.
Here is the starting point for the hub, a chunk of 3" diameter cast iron bar.
One side was machined to the finished profile and bored to size all at the same setting.
It was then reversed and held on a mandrel to do the other side.
Next transfer to the milling machine and indexing head for the eight spoke holes. These will be bored over size and then fitted with protruding sleeves to mimic the casting.
Tapping size for the M5 spoke securing screws.
Opening out for the sleeves.
Extra tapping size holes for hub securing screws either side of centre.
A few sleeve blanks bored to size but still to finish on outside diameter.
Finishing a sleeve to size on a mandrel.
These sleeves will not be coming out again any time soon.
Having left to cure for 24 hours, the sleeves are machined to finished length whilst still in the indexing head.
Next lots of tapped holes.
The four equally spaced shallow keyways needed a special tool to use with my push broach to ensure they were spaced accurately. Here is one I made earlier.
One keyway is broached first, then the bush is indexed around 90° for each subsequent one.
This is what it looks like after four passes.
More to follow soon.
Phil