Morning all.
Despite storm Bert I managed to spend most of the weekend in the workshop. There were two main components left to make, the crank and flywheel. These were made from the same piece of 50mm brass round bar.
I started on the crank first. This was an interesting piece as it started on the lathe, went to the mill, back to the lathe and a final trip on the mill.
This is it after the first turning operation, which involved bringing the overall diameter to 28mm, stepped down for the boss to 10mm and the 5mm drilled and reamed central hole added. Then it was over to the mill.
The piece was located off the central hole, the second M3 tapped hole added for the crank pin, and the scallops cut, then back to the lathe to be parted off.
While the stock was set up in the lathe I switched to machining the flywheel. This was reduced in diameter slightly just to clean up the edge, a 6mm central hole drilled and reamed, and dished out. This appears to be more cosmetic than necessary and went OK. I used a form tool I had made a while back and had quite a lot of chatter, I really need to grind a proper trepanning tool.
Brass is lovely to machine, cuts really easily and leaves a nice finish, but the mess!
With one face of the flywheel completed it was necessary to part off and turn the other side. My parting blade isn't deep enough to reach the middle of such a large part, so I went as far as I could and hacksawed the rest. With the flywheel flipped over it needed mounting back on the lathe concentrically, so a piece of aluminium bar was chuckled up and a 6mm spigot turned. The central hole wasn't visible yet (brass is expensive so I had only drilled just deep enough) so it was initially held on with CA glue until the waste material was faced off, then once the hole was fully visible the arbor was drilled and tapped for a retain screw, and the remaining features machined.
Back to the crank, this needed a radius added so I made up a couple of filing buttons and removed the excess material by hand.
Both the crank and flywheel needed a means of securing to the crankshaft, so each was cross drilled and tapped M3 for a grub screw. And that was the crank and flywheel completed.
Now, remember that long hole in the frame right back at the beginning of the project? Well that needed to extend into the bearing so that the steam/air could get too and from where it needed to go. The bearing, inlet pipe and inlet pipe bracket were fitted to the frame. The bracket and pipe determine the fixed position of the bearing, so the assembly was placed upright in the mill and a 3mm drill passed down the long hole and drilled through the bearing.
There were two last small parts to make, the plug for the end of the long hole, and a pin for the cross hole on the flywheel for the grub screw to bear against.
These are all the competed parts.
And the assembled engine.