I've been looking into a Makeblock robotics kit but have found no information on the web that comes from end-users, and one of the main advertised features is not clear to me: The slot threads shown below are straight, while the screw thread that will mate with them is angled. Is there just very little contact between screw thread and rail thread vs. regular screw hole threads? Or would the screw want to rest angled somewhat- and then the head would not be flush with the rim of the rail? Or would the screw deform the aluminum rail if over-torqued?
This is a close up picture of the slot with screws: