Algodoo

This seems like an overly-complex solution for a simple problem!

Anyway, concerning your scene, it has only one minor issue, and that is the "Instant Center Mechanism" gets stuck when closed and I try to open it. I found I could correct that by increasing the torque values on the two axles. I increased each by an order of magnitude, but I'm sure a lower value would probably work too.

Nice job!

Xray: This seems like an overly-complex solution for a simple problem!
Steve: I agree, but you don't state the problem nor a simpler solution. The problem, as Andrew Klein sees it, is that the table needs open access in the middle of the table. If the table did not have a slot in the center that needed open access down to the floor, then the simple solution would be to weld the nuts to a common bar and have that bar pivot at the center of the table. The problem with the instant center approach is that it's an approximation and has limited rotary range. The problem with both approaches is that the linkages act as separate swivels as opposed to a common bar with a pivot in the middle. As a result, the nuts squeeze the screw ends towards each other with a theoretical infinite force when there is tension in the screws. Algodoo shows 1134 pounds squeezing force for the instant center and 15 pound squeezing force for the remote center when a 10 pound clamping force is applied. Both values are excessive. That is why the inventor states that the mechanisms need to be clamped to the table before full clamping force is applied.

Note: It's easy for me to act like an expert and criticize someone else's design. The fact is that the inventor made a design that works well and he is selling it. That's quite an accomplishment. It's a long hard road between having an idea and creating a marketable product.

I'm the first person to admit that I'm no expert in ANY field. I just made a "seat of my pants" evaluation without doing any of the hard work of testing and evaluating this device. That's all I am claiming. I looked at it as a noisy, complex jumble of gears, lead screws, hinges and other mechanical devices and said to myself, "That could probably be simplified with two separate lead screws and two cranks." It would require more motions to clamp an object in my version of the device, but it would be simpler and less expensive. I had no intention of insulting the design of the device. Lord knows I am not qualified to do so! It was just an observation.

Thanks

EDIT: The scene has been greatly improved. Nice work.

Just a thought: I was wondering if putting a "Quick Release Nut" on each screw would be useful, and without adding too much complexity to the overall design. Your thoughts?

I concur. If there was a quick release nut for each screw then you wouldn't need the geared transmission. The pipe clamp twin screw vises seem to be the simplest implementation. Clever Quick Release Pipe Clamp Vise for my Workbench looked interesting.