50 years ago I saw a cannon at the castle of Buedingen in Germany. After I took several photographs I build a model of it from steel and wood. To make it more decorative I designed the metal fittings a little ornate.
Some time ago I went to see the cannon again for further details but it wasn't there anymore. So I can't say what type and what size it was.
After I uploaded the naval cannon https://cults3d.com/en/game/naval-cannon
I also wanted to design this one but I didn't know how make proper wheels which are printable. The only way I found, is to make them in the same way as in real. But the spokes where still a problem, till I decided to split them in two half.
The most realistic way is to make the felloe from 6 segments. If you want to use the complete felloe in one piece you must take the split hub. So you can first put all spokes into the felloe and then push the two half hubs together.
Update 22. Sept. 2017
barrel centring pin.stl
In order to make all parts to be printed, I had to make some changes.
The only things you have to get is:
3 mm x 190mm shaft from brass for the axle. You can flatten the ends with a hammer. Then drill a 1,5 mm hole.
Some nails and needles to fasten the fittings.
3 threaded rods M3 x 56mm with nuts.
1 rod 3mm diameter x 49mm