Note: This model is a correction to the original 8 cylinder radial engine model I built before. I realized after publishing the previous version that 4 stroke radial engines need to have odd number of cylinders. As a correction, I modified the the cylinder block to have 7 cylinders instead of 8. Most of the parts are identical to the previous one, so if you have already built the 8 cylinder version, you can re-make a few parts and make a more "realistic" radial engine model.
To assemble, print the following parts, and follow the assembly procedure.
Hub Bottom (Requires support)
Piston (x 7ea) *
Rod (x 6ea) *
(Parts with an asterisk are identical to the 8 cylinder version. Note that you need 1 less of piston and rod.)
The "un-sectioned" cylinder block is also uploaded, but I have not tried printing it (I am not entirely sure if it the parts can be assembled into it).
I designed in some slack in each of the parts, but you may want to make sure that all parts fit with sufficient clearance for smooth motion