I'm in need of drilling some pilot holes for wood screws that end precisely at 1/2", perhaps even a tad shallower. I need a drill bit stop or means of preventing the drill from going too deep. I've not seen such a things at a box store, though it looks like using countersink bits, backwards, might work (they are often hex drive, so if I put the countersink part in no chuck, the 1/4" hex would act as a stop). I've also thought that perhaps a series of washers stacked, or a piece of wood with the bit set to just deep enough past the bottom of the block with the drill going through it, might work. So, what would you recommend? I'm looking at drilling for #6 and 8 screws. Thanks!