Undo a screw when the head has been rounded off?(not by me i hasten to add). I'm trying to remove some really old(from the 70's) kitchen units but the screws look oxidised and i cant get a purchase on them. Its a tight space too. I've tried whacking the cupboard with a hammer in temper but it hasnt worked
If you have them DC, turning with a set of pipe grips or mole grips to put extra pressure on the screw head, whilst persuading with the screwdriver.....And not forgetting the obligatory curses of course...
Failing that, it means cutting the head off somehow to dismantle the unit, then removing the thread body with pliers afterwards.
i try to knock em round with a chisel so they unscrew - put the chesel on the top half of the screw and knock it anticlockwise. once it moves they fly out