I'm trying to drive a 2 1/2" long 3/16" diameter tapcon into a 50 year-old concrete slab/subfloor to attach a new toilet flange.
The instructions on the case of Tapcons said to drill a hole in the concrete with a 5/36" bit. Did that with a Bosch Bulldog SDS; that part was easy.
Next the instructions say to drive the screw in with a #2 Phillips head bit. So I put a new #2 bit in my Bosch 1191VSR drill and switch it into hammer drill mode. But I can only get the screw about 1/2" in and then it just stops turning, and the bit comes out of the screw head and begins to strip the screw.
I feel like there's some technique I'm missing, or else my bits are defective. But I tried two different ones, and the same thing happened each time. Or maybe it's my drill? From stationary, I can not get the screw turning. I need to back it out a bit and start again. It feels like the torque is too low at slow speeds.
What am I doing wrong?