Almost two years ago I made a large heavy duty G clamp so that I could clamp things down to the bench so that what ever was clamped wouldn't move easily when I hit it with a hammer, I also wanted a clamp that wouldn't twist or self destruct when I applied a lot of pressure to it unlike a few of the commercial ones I had which proved to be not up to the task at hand.
Anyway I had some scrap pieces of 16mm plate to do them out of and only managed to get one done at the time, so almost two years down the road, I got tired of looking at the spare plate, and every time I did I said to myself... I really should make another, so the time has come, I finally had some spare time and since the weather has been lousy here, I thought that I should stop procrastinating and make another. The body in this one is about 50mm wide x 16mm thick with a piece of 40mm x 6mm flat bar welded to the side for more sideways stability.
I plasma cut the rough shape and ground off the edges then put the flat bar into my vice and bashed it into the shape required to go around the body, welded the top pad and then the flat bar to the body.
The cap is out of some 30mm stainless steel round, drilled and 4 slots cut into the top where the thickness was reduced a bit, I tightened the welded clamp to my bench and hit the edge of the cap till it closed down around the shaft end which still allowed it to swivel but not fall off. Should have used 3 cuts as it wasn't all that easy to get the cap to close around the end.
The handles are 14mm steel rod out of a old printer with stainless end caps (which were press fitted) for quick tightening and if I need to clamp something really tight I just use a big shifting spanner using the nut at the bottom of the thread shaft.
Pic 1. Threading the 30mm x 3.5mm shaft.
Pic 2. Tapping the nut.
Pic 3. Pad and nut welded to clamp body.
Pic 4. Large nut to be welded to bottom of shaft for extra tightening power.
Pic 5. Swivel cap for end of shaft.
Pic 6. Clamp welded up.
Pic 7. Both clamps together.