[Enigma's puzzle]

I don't like putting bearings in the wood personally, wood warps and cracks, when you put only a single bearing in the wood (as in the front and middle shafts), with just about any stress it will tear out your hole. The shaft will then shift off-kilter and throw chains on which ever shaft is loosened. But the bigger problem will be your hole being ruined, you would have to replace the entire side of the frame.
Maybe a 1/4 inch metal plate on the inside and outside with bearings in each. I know it increases the price but i would do it if at all possible because your out for at least a couple of matches if not the rest of the day. A little catastrophe defense.