Adjust C-Clamps in Seconds

[Toolmaker51]

There is no substitute for older heavy duty C clamps .......snip.....often called boiler makers clamps. Want to use them as a fabricators clamp get a Colbalt drill bit and cross drill the head of the screw get a hold of some stress prof rod the diameter suitable to make the bail pass it through the head heat the ends and mushroom them. Now your 25 lb 8" clamp that is the "C" clamp from hell, and you can still wrench on it

Uhh, no.
Years [decades] had an order to drill square head set screws for safety wire, both sides. Jogged the holes to not cause interrupted cut but it was still surprisingly difficult, just .078 or so. Not only case-hardened but D-EEEEP. A split point cobalt could only do a few holes. It got better peck drilling with the quill stop, coolant not very noticeable, but good cutting fluid improved it once more.
If I had to repeat, there'd be a box jig with drill bushings.
The look of heavy pattern clamps says they are the same screws.
A wrench will do.