Thanks, all, for the kind comments.
After a brief hiatus to work on my mill / drill and add DRO's on the x and y axes, I got back to work on my engine today. I finished up the two connecting rods. Here in the first picture you can see the fixture I made to hold each connecting rod for machining.
Inside-Out Steam EngineI first milled the edge of one side, then took out the screws, flipped the rod over and did the opposite side. After finishing the edges on both rods, I changed end mills to a 3/16" and milled the groove down the center of each side. Finally, I rounded the outside edge of the small end.
Here are the finished rods...
Inside-Out Steam EngineAnd an idea of what they will look like on the engine...
Inside-Out Steam Engine
Inside-Out Steam EngineThe whole process was a good exercise in using DRO's for positioning. Makes for much more precise locating than trying to machine up to scribed lines and marks.
I think I only need to make and install the crank arms to be able to test the engine. And of course I'll need to make a base for it sooner or later.
Chuck