Not sure what you're asking. The angle irons clamp to what HP is calling the rail, in the second picture.
The "jack screws", the ones with the wing nuts, straddle the rails. The person doing this would only turn those screws like 1/4 to 1/2 turn at a time, alternately, until the joint is defeated. The jack screws being 1/4-20, move 0.05"per full turn. So that makes 1/4 turn move 0.0125". Like most things 'mechanical' it takes finesse, not brute force.
The "jack screws", the ones with the wing nuts, straddle the rails. The person doing this would only turn those screws like 1/4 to 1/2 turn at a time, alternately, until the joint is defeated. The jack screws being 1/4-20, move 0.05"per full turn. So that makes 1/4 turn move 0.0125". Like most things 'mechanical' it takes finesse, not brute force.

