[rheavn]

Chester's design on this tool is very good. If you want to build one you need to use the 1/2" Pony pipe clamps. The reason is that you need the clamping lever to be able to slide to avoid interference with the coach as you tighten or untighten. The 3/4" Pony pipe clamps have a non sliding type clamping lever.

1/2" http://www.amazon.com/52-2-Inch-Clamp-Fi...B0000224CA

3/4" http://www.amazon.com/Jorgensen-50-4-Inc...pipe+clamp