I'm planning to screw plywood to a partially-built cabin floor using Robertson screws (square head). I want to use a cordless drill instead of an impact driver to reduce noise. It's deer hunting season so I don't want to scare wildlife away from nearby hunters. Off-grid location.
My experience with using a hex screw bit in a cordless drill is: the bit sometimes slides out of the chuck, which is annoying.
What can I do to prevent the screw bit from falling out?
It's not the cordless drill - it's the keyless chuck on the cordless drill. Those will self-loosen (due to the inertia of the adjusting sleeve) if the drill is stopping suddenly. Or if it's started suddenly in reverse.
So if you are driving screws at top speed and letting the torque overload stop the driving, or otherwise stopping suddenly, they are likely to loosen. Mine will unscrew itself and release the bit if I have it running at speed and let off the trigger suddenly, because it has a spindle-lock when the trigger is off, so it stops quite abruptly. The outer sleeve you grasp to tighten it wants to keep spinning.
Simply slowing down as you get close to finishing each screw will reduce that problem vastly.
Not simply, using a keyed chuck would do it, but that's going to be you replacing the chuck on your cordless drill, and is a hassle and expense.
Or the serious off-grid and stealthy-quiet solution is to use a bit-brace to drive your screws. Back when NiMh was the top technology for your rechargable drill, after I used up my two batteries I'd grab this out of my bucket and keep going, blowing the minds of folks also waiting for their batteries to slowly charge. That's been less of an issue since Lithium-ion rechargables with fast chargers showed up.
As mentioned in comments, the brace in the picture above has a standard brace chuck which is holding the hex bit in jaws not really designed for it (though it works fine in my experience.) An adapter is available, though I have not purchased one.
Image sourced from Lee Valley Tools no endorsement implied.
When I don't tighten the chuck tight enough, the hex bits can slide out of my hand-tightened keyless chuck. When the chuck is tight, though, the hex bits remain firm.
I have had times where running the drill fast while holding the chuck to tighten allows the hex bit to grab slightly turned from the optimum position: hex sides perpendicular and at right angles to the chuck jaw grab edge. The jaws are just a hint wider then, allowing the bit to rotate a little and loosen out.
Exaggerated example:
When I run the drill slow to tighten, the bit is grabbed firmly and does not loosen, because the bit is allowed to slip a little as the chuck tightens, into the optimum perpendicular right-angle position.
Try tightening the bit slow for the final few turns.
Using a longer hex bit may help, the little one inch bits always come loose whatever I try, the longer ones are better.
Also you could put a rubber ring on the pinched part of the bit to prevent it from falling out if the chuck loosens.
