Well, tonight I’ve had one of those evenings when you discover that your fine, shiny 2-dimensional plans have been complicated by the subtleties of a 3-dimensional world. For reasons that may include the existing frame not being a perfectly square C-channel, despite my best efforts I have an error in my measurements and therefore in the shape of the new frame segment. A very slight error, but one I intend to correct before I go any further.

(Read on …)