Another Tubing Tool

[deepwoods]

Curved jaw Vice grips are most common in 10" and 7" size. Which size is used to build tubing tools?

Followup- for the benefit of anyone else seeking the same information.... The 5WR size of the curved jaw vice grip works well for the tubing tool I made using the OP's plans. The Pruno website is where I found the answer to the vice grip size question.

I built the tool for use with 3/16 tubing, using 5/16 coupling nuts for the tubing gripper. The geometry of the plans is good. Rather than cutting and rewelding the handle parts, I heated the 3/16 X 1" flat steel bar with an acetylene torch and bent the steel to the final shape.

[maple flats]

So you don’t have any threads left inside the couplings

When you drill out the long nuts you only drill half way in from the end facing the other long nut. That way the threads grip the tubing, while the fitting barb can fit into the larger half of the long nuts. I might also be a good idea to grind off a little extra from the cut surfaces where the long nuts were cut in half. That allows more adjustment to get a good grip. Also suggested you use a round file to "blunt" the remaining threads in the long nuts so you don't nick the tubing, giving it a place to fail.