I use 1/8" bits as a starting drill for almost every hole I drill - cast iron, sheet metal, aluminum etc. I still don't get it. why 1/8" size is a bit $2 but the manufacturers seem proud of them. The first bit out of the box drilled about sixty holes in 18g steel and a few pilot holes in a 3/8". -Cast - it worked as well as anything I've used and way better than blistered junk from the local hardware store I would buy this product again without hesitation.