The attatched photo....if it worked...is of a vice I built several years ago from
readily available, hardware store stuff. No welding involved, just some drilling and
tapping for the set screws.
Its vary rigid, and versatile....swivels and pivots, and is height adjustable by
replacing the upright with a longer piece of pipe.
The elbow can be removed, and the clamp can be screwed to the upright, so
as to hold the knife vertical.