Very nice table, wish I had one. "Platen table clamps" perhaps? Those clamps are fancy, the last time I got to use one of those tables, the clamps were a simple "J" bar of sorts that held planty tight just dropping them in place. An extra tap with a hammer made them immovable, and an appropriately directed hammer tap was required to remove them.
The pipe was 11 inches long and has a diameter of 1.660 inches (1 1/4 schedule 40 pipe), take a chunk of 3/8 inch cold rolled 2 inches X 9 inches and weld to one end of the pipe (weld all around the end of the pipe).
Clamp the pipe in the vise and heat the cold rolled so you can bebd it down about 30 degrees.
The cold rolled is then curved back in a gentile radius.
Eric advises that his table has 1 3/4 square holes so if yours differ the pipe needs to be about 1/8" smaller.
You can make these longer or shorter by shortening or lengthing the pipe. The ones with 11" pipe will hold 6-7 inches.
He has made some screw clamps like the one you showed in your original post but he says the pound in DIY ones he made are often faster and easier.