"Never heard of a chigago screw." the kid told me.
"You've got them, let's go look" I replied.
And he had them, but they were labeled Post Nuts, which I guess makes sense, because it's a standard machine screw with a fancy threaded post and flange for the nut. I bought the three that he had, then two days later needed more and went to Lowe's in town. I asked for Chicago screws, got the same blank gaze. But, the hardware guy and I looked and found them. For the record, they look like this.
A sex bolt, (also known as a barrel nut, barrel bolt, Chicago screw or post and screw), is a type of fastener (nut) which has a barrel-shaped flange and protruding boss that is internally threaded. The boss sits within the components being fastened, the flange provides the bearing surface. The sex bolt and accompanying machine screw sit flush on either side of the surfaces being fastened. It is normally chosen because of its low profile compared to other nuts. The sex bolt often has a built-in feature, such as a slot, to aid in tightening the fastener. Some sex bolts, more commonly known as architectural bolts, have knurled barrels to allow one-sided assembly. Binding posts are similar to architectural bolts in that they are designed to be assembled from one side, but they have teeth on the flanged surface to keep them fixed.At any rate, I found a few at Lowe's and have enough to finish the project. What I did find interesting is that the name my dad and grandad used must be an archaic term today. And, I learned that I can buy them at Amazon.com.
Another bit of arcane knowledge from PawPaw's House.