If the only tool you have is a knurled brass insert, well, then, you use ’em everywhere:
Those are mounting holes for the little trim tab that closes one of the two holes left for the door hinge bracket on the vent grill of our refrigerator. The tab originally had a pair of the flimsiest little plastic pegs you’ve ever seen, both of which broke off and got themselves repaired with epoxy at least once along the way.
The holes in the bosses started out only slightly larger than the 4-40 insert body diameter, so they were surely undersized, and the knurls definitely stretched the plastic on the way in. I applied a soldering iron to the studs until the plastic melted around the knurls, relieved much of the stretching, and secured those puppies forevermore.
I was willing to try heat-setting them because I absolutely didn’t care if they came out a little crosseyed. For future reference, the inserts will cant off-axis unless they’re held in place: use a drill press or something similar as an alignment fixture. That would be awkward with three feet of grill hanging off the drill press table.
I step-drilled (to avoid grabbing the soft plastic) the tab with slightly oversized 1/8 inch holes to allow some adjustment for best fit. A trial assembly showed a pair of greatly oversized 6-32 nylon standoffs spaced it well enough from the bosses for my simple needs:
The two broken pegs sit disconsolately atop the tab, with the crushed section of their ribs showing their depth of insertion in the bosses. Note that the tab sits proud of the grill, originally supported entirely by the pegs and stopped by the square block in the middle, with no support or alignment on any side.
The left peg popped out of its epoxy blob, forcing me to file the blob flat before drilling through both it and the tab.
After some wiggle-n-jiggle adjustment, the tab lined up a bit better, I defined it to be Good Enough, and popped the grill back in place on the refrigerator.
Done!
The Smell of Molten Projects in the Morning 