While straightening a prop shaft I found myself in need of a Q & D (quick & dirty) machine jack. I know you guys usually make stuff that looks like it came from NASA but maybe some one will have a use for this, it sure worked for me. I welded a 3/8 x 16 threaded rod coupler to a 1/2 inch pipe nipple then threaded in a 4 inch carriage bolt. It's quite strong and you can make it any length you want by adding a pipe coupler and more pipe. Each full revolution is .0625"