Screwheads; was 5 floppy?.

On 25 Nov 2008 at 18:45, David Griffith wrote: To engage a Torx or Robertson, the screwdriver bit must be fairly precisely positioned so it enters the head. With a Phillips, one can still engage the head successfully even if one starts off-center due to the property that both the slot and bit are conical in profile-- the bit will naturally tend to slide to center in the slot. The price you pay for this is that it's not easy to preload a driver with a screw without some sort of clip or magnet arrangement. Torx and Robertson-headed screws can be preloaded onto the bit which is one of the reasons that manufacturers like them--which is also, why, I suppose that square-drive drywall screws have largely replaced phillips-head ones. I did better than that--I used a special-purpose screwgun that releases as soon as the head is driven flush with the surface. The problem is that stainless deck screwheads are rather soft. Driving 4" #12 screws into green Doug-fir joists requires a fair amount of torque, even if one predrlls the first inch or two of the hole. Cheers, Chuck