I am about to install a Veritas Twin-Screw Vise in my new bench. The instructions say that the jaw can be any length, so I am planning to have the jaw extend 12 inches past each of the screws. This is the 24 inch model, so the total length of the jaw would be four feet.

Any comments on having the jaw extend this far would be appreciated. The concerns I can think of are:

1) Is  there a practical limit to how much the mechanism can resist racking?

2) I would like to make the jaw 3 inches thick and 7 inches tall. Is that much wood (hard maple) too heavy for the vise?

Thanks