I have built the extra-wide vice which I discussed in several threads here (paint and wooden jaws are still to come). Thanks for your thoughts and suggestions. Here are the pictures:
https://www.flickr.com/photos/138493...57663551210144

In the end, I decided to use two scissor mechanisms shortly before my leave from work began. I did a few calculations and figured I could fit a sturdy mechanism inside two lengths of channel. I'm pretty pleased with the result. Jaw width is 75 cm (30"), so it's as wide as the largest Black & Decker Workmate.

A couple of observations:

- Stiffness and ease of adjustment are great. Clamping asymetrically using half the jaw width is possible with hardly any flexing. Clamping a narrow piece of wood at the very end of the jaws (with nothing at the other end) causes a little flexing, but isn't problematic. The single handle with 1/2" jaw movement per turn allows quick adjustment.

- The downsides are the weight of something like 80 lbs (I might need to add a little stiffening to my steel bench frame) and the fact that it can jam at the very end of its travel. It was designed for a 6" jaw opening. Jamming occurs beyond an 8" opening, so it works according to my design, but I might add some kind of stop to limit the travel. And I haven't lubricated the scissors yet.

Enjoy the pictures. Comments and questions are welcome.

Best wishes,

Chris