Good to see someone post this method with masonry bits. Years ago when I was repurposing "excavator bases" for the oil drilling industry I used masonry bits in large hand held slow speed electric drill to remove the broken off under carriage bolts, I found that new unused bits from reputable manufactures to be the best with the double "V" sharpening the best as they came. Most of these broken bolts/studs where 5/8 - 3/4 inch drilled cold, no lube just water.