No, he was referring to making a nut that when finished has two external diameters. The larger diameter would slide through the wider area at the base of the slot (the bottom cross-bar of the inverted tee,. The smaller diameter will slide through the vertical part of the tee. The danger in using this (and also the one drawn above) is that the clamping area is very short, and is prone to breaking out the top of the compound. The same thing can happen if you use an available clamping nut. Generally, the length of the T-nut for compound service in a cast iron compound should be about three times the width.
Thanks for the input. I made a beer trade with a buddy who has a mill to make me a foot or so of blank t-slot which I can cut to length, and tap to fit my clamping bolt of choice.
Thanks again all for the input.
Unfortunately, unless you found some specialty ones instead of just the standard T-nuts, McMaster doesn't have anything safe to use. They are all too short and mostly too narrow for safe use on Atlas compound slides. No one wants to have a crash. But if you do, far better to break a gear tooth than the compound slide. The T-nut width should fill the slot. And the length should be about the width of an AXA tool post.