Hi everyone, been meaning to do one of these for ages, I got tired of the flimsy commercial G clamps that are available, there have been many times that I wanted to clamp something to the bench with a bit of force so that the work piece won't move when I need to hit it with a hammer, and if you tighten up the commercial ones up too much they start to twist or self destruct.
This one should last me forever. Might make another one when I have some more time. Drilled a 16mm hole for the handle, but didn't have a piece of round steel lying around so that will be added later, however I welded up a large nut on the bottom of the screw so I can tighten up the clamp using a shifting spanner.
Unfortunately some of my pics disappeared so only have ones from the raw plate to the welded clamp. Sorry, but it appears that my camera has Gremlins.
The plate is a 16mm piece of scrap I picked up, plasma cut out the shape and then ground to clean up the edges, the flange is 40mm x 6mm flat bar, fully welded around the outside, the screw has a 30mm x 3.5mm thread and made from a piece of scrap trailer axle I had, the nut is from a 45mm square bar. lastly the top pad is 12mm x 40mm flat bar. The screw pad is a bit of 40mm round, drilled and turned with a slight angle inside on the top 8mm and then slotted with a cut off disc, wound the screw into the clamp, inserted the cap on the screw, put it into a vice and hit the top edge till the slots closed around the top part of the screw ball.
Painted it with a coat of primer and 2 coats of grey Hammer tone paint. In the last pic I added a drink can for a size comparison.