Blacksmith's foot vise - video

[Frank S]

Does anyone know if there's a reason why you wouldn't want the moving jaw to pivot to keep it relatively parallel to the fixed jaw when you're clamping? I'm certain the fixed arrangement is stronger and maybe, pinching the work with just the top of the jaw works like putting a rod/wire between the work and the moving jaw on a mill vise. Also, did he dip his drill in borax powder when he was drilling one of the medium sized holes? Whatever he was using, I haven't seen that before.

It would be hard to clamp small parts with a movable jaw. having a fixed jaw set to be parallel at near its widest opening will insure clamping force is always at the top of the jaws, but moreover it is a trade off between simplicity of design and better clamping force,
The way I skip through most videos I missed the event you asked about, I only saw him using 3m oil for his drilling