Screw Jacks

This is a pair of Machinist's Screw Jacks that I made out stainless steel. They are adjustable height jacks used for supporting workpieces. The top thread is right hand, and the bottom is left hand, so they open up simply by turning the center section.

 

Here's a video of one in action:

www.youtube.com/watch?v=D701rJZsck4

Done