Bird Box: Rotating T-Nuts

A bird box from long ago emerged from the heap and took its place in an upstairs window:

That big open back held an acrylic sheet letting us watch wrens raise their family; snugging it against the window makes that sheet superfluous. We’re hoping to lure the Wreath Finches from their preferred spot by the front door, but we’re open to any birds in need of a nesting spot.

The aluminum angle formerly securing the box to various wood window frames wasn’t going to work here, so I conjured a pair of rotating T-nuts to fit the track in the plastic window frame:

They’re made from a 5/16-18 T-nut and two layers of 3 mm plywood, all glommed together with E6000-Plus adhesive because it did not scamper out of the way when I opened the Adhesives Cabinet.

Some doodling convinced me a pair of quarter-circles welded back-to-back, minus cutouts for the metal T-nuts, would suffice:

The radius must be a little less than the width of the opening into the channel (20 mm) and the diameter must be a little more than the width of the channel behind that opening (32-ish mm), so I picked 17 mm. The metal T-nut flange is just over 20 mm, but the spike cutouts (omitted from the LightBurn layout) let it slip through the opening.

A random block of wood positions the box away from the frame enough to clear the outermost flange carrying the screen. Drilling oversize ⅜ inch holes countersunk the top of the T-nut into the block and eliminated excessive alignment fussiness.

Slicing 20 mm off the bolts fit them into the space available, with a pair of stainless washers covering the gaps.

A doodle with measurements you won’t need, but surely handy for mounting something else around here:

Now, to see who takes up residence …