How To Clamp Pex Fittings Without Tool . Insert the pex fittings into the ends of the pex pipes. Pex crimp is more resistant to rust as compared to clump tools. BJ0010C Rachet PEX Pipe One Hand Cinch Clamp Tool ASTM F2098 from iwiss.com Crimp rings should be 1/8 to 1/4 of an inch from the end of the pex. It works with 1 inch to 3/8 inches cinch clamp rings. Then, use wires as a way to make the crimp part.