Originally Posted by Frank S Originally Posted by

If you use a modified buttress or breech-lock thread and a half nut on each side it will be stronger than acme thread.

I used to have a vice on my radial drill with the quick release half turn and you could lift the screw from the half nut slide the jaw to touch what you were clamping then lay the screw in the nut give a half turn and the part was locked in good and tight.

Modified Buttress threads come in different arrangements mine was concave on the screw so the nut hooked into the screw