I'm trying to drill some 5-10mm holes in 1-1.5mm thick steel. I'm using a DeWalt DCD777 18V cordless drill with Bosch HSS bits (which claim they're made for drilling into metal). Both the drill and the bits are brand new.
No matter what I do, the bit almost always binds into the metal just as it's about to exit the piece I'm drilling, starts twisting inside the chuck, and gets damaged.
Here's a photo of the damaged bits. You can see, especially on the bottom of the bigger one, how the inside of the chuck rips into the bits.
Now, my question is not about how to stop the bits from binding, I've found plenty of advice about that. My question is, is it normal for the bits to slip like this once they do bind? I've been told that a keyless chuck is not as secure as a keyed chuck, which of course makes sense, but how can I tell if it's normal behavior or a faulty chuck? As I said, the drill is brand new, I can still return it and get a refund (or another drill), but I'd prefer to do this only if the machine is actually faulty.
I am pretty sure I tightened the chuck as much as it's possible to do by hand. I'm a pretty strong guy, and the method I use is: one hand on tool, the other on the chuck sleeve; tighten as hard as I can, until I can no longer get it to ratchet. I've also seen videos like this, which advise to back up the chuck a bit after tightening it, to engage the spindle lock, and I tried that too.
The bits do not slip at all when drilling into wood, even on holes as deep as the bit is long. Even when drilling steel, they only slip when the bit actually binds.
So, any tips on how to tell if a chuck is weak?