The screws in question are 4.5 x 30mm A2 stainless steel hinge screws. As far as I can tell, they are good quality, branded (TIMco), double-countersunk, manufactured by thread rolling.
Material is hardwood (oak) with 2.5-3.0 mm diameter pilot holes, so a high index of friction.
A drill clutch would constrain the max torque to an adjustable limit, but in this case it was decided to fit the screws manually given the size of the screwheads relative to the hinge screwholes.
Given that one can usually deliver several times more torque using a T-handle screwdriver than a normal screwdriver, is there risk of screws like this breaking when handled this way?
Best Answer
In general, if you have a good quality screw and you are going into piloted holes, you shouldn't need enough torque to break the screw. If you really bear down on it, it's not outside of the realm of possibilities that a screw will break, but it shouldn't be common.
If the screw is particularly hard to drive you can lubricate the threads with a little wax or soap to reduce the torque needed to fully drive them. Once the heads are flush with the surface of the hinge, you should not need a lot of additional torque. If these are phillips head screws, it's more likely they will cam out before the head breaks off when using hand tools.
I have broken cheap "drywall" screws with hand tools in the past, but I've never broken a better quality screw (like a decking screw) unless I was using an 18v drill or impact driver.