[RRLedford]

The proper way of tinning for this type of a screw against pivoting clamp bar connector scheme is to tin only the very tip of wire, and then cut most of the tinned end off, leaving mostly only bare copper to mash down at the point directly under the screw and further out, but with a short zone of tinned remaining at the far tip of the wire.

This produces a reversed wedge effect, such that the tinned tip of the wire is the big end of the wedge, and the clamp piece then squeezes tighter as the wire gets pulled, since the tinned tip will not flatten out as much or as easily as the bare copper did when connection was tightened. Thus, the clamp bar grips the wire at an angle, tighter at the exit and looser further inward, and this effectively locks the wire inside the clamp.

-Dick Ledford