Hello I am trying to build a little contraption for a home project and part of this build requires me to drill 1 inch diameter holes in multiple slabs of 1/2 in thick steel. Not sure what type of steel it is but it's just your average run of the mill half inch by 4 inch wide by 18 inches long slab of steel. My problem is that I have used my good drill bit set to step the hole size up to 3/4 inch. I did not have any larger bits so I went to Harbor Freight and purchased a set of Black and Demming large size bits (Chinese made) The 7/8 inch bit and 1 inch bit just spin at the top of the hole. They don't cut in. I am using a squirt bottle filled with automatic transmission fluid as lubricant (is that ok?) I have been using a high end Milwaukee corded power drill to do the drilling. It has worked fine at drilling the holes up to 3/4 inch but the new bits won't do anything to the steel slabs. I sure the bits I got at harbor freight are low end Chinese crap but they said they were black oxide coated and made of high speed steel so I thought they would do the job? My question is: What is actually the proper type of bit to cut 1 inch size holes in 1/2 inch thick steel? Would a regular bit work if it was not black oxide but maybe titanium nitride coating? Should I get a cobalt steel bit or carbide tipped? Or should I be using an annular bit, or an end mill bit? Thank you for any advise you could pass along.

How can I make about 30-40 Volts DC ARC Welder using an alternator of a vehicle and/or a transformer of a Microwave oven. Please give me a detailed report including the conversion from AC to DC. I hope that it will be possible to weld thin metal sheets using such a device. The main idea is to repair car bodies without damaging the Zinc coating of the new plates and surrounding paint work.