Poor man's "T-slot" knob and stop block

Simple knob and stop block I modeled for my father's radial arm saw bench he built.  He routed a "t-slot" into the wood and initially made use ¼x20 hardware which works fine. But he's already ordered some t-bolts to use as opposed to the ¼x20 bolts as a minor upgrade.

The knob needs to be paused so a nut can be dropped into the print.