just from experience, you can feel the pressure in your hand tightening bplts to there max with out a torque wrench. I suggest to you is go get a dozen 1/4 20 nuts and bolts and experiment tightening them. The fiest 3 tighten till you strip them, keeping in mindyour hand pressure. after a few tries you well know the lim9t on the threads you are tightening. You well relize it, just pay attention to your hand pressure and at what pressure the threads are gonna strip. Once you have the feeling, like rideing a bicycle, it well never lesve. wheather it is 1/4 20 threads or 1/2 12 threads dont matter. the touch well be the same.