|MadSci Network: Physics|
Hi Jim. Ideally, you'd like your "driver" to have as much surface area as possible with the "screw". This means you'd like to have as deep a slot/groove/etc on the "screw" as possible, with lots of length to it (why you get a slot that runs all the way along the head of the screw). Let me start by saying that the ultimate answer involves (of all things) money. It's cheapest to make slot head or phillips head screws, and more expensive to make hex or square drive recessed screws. If you're tightening a slot or phillips screw, and it stops turning, you have to apply more torque, while simultaneously pushing the driver into the screw. If you don't push hard enough while you're turning, your torque will cause the driver to push back, thereby starting the process of stripping the screw head. A solution to this problem is the hex or square drive screws. You don't have to exert a forward force on them to tighten, so they don't strip so readily. So, if you don'y mind spending a little more on your screws, the hex and square cap ones generally strip less often. Does this answer your question? email me if you'd like to discuss it more. Best Regards, Mike Weibel
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