A few years ago when I got my 66 Commander, I did a full brake job on it. The brakes had worked "OK" but the linings were getting thin and the car had sat for a few years, so I got new shoes and wheel cylinders. I had the drums turned at a local shop, and when I went to pick them up, the mechanic said one of the front drums had a "hot spot", which he pointed out as a small dark spot on the turned surface that was about 3/8 of an inch in size. He said it might make the brakes pull on that side and when I installed the drum, braking did get that warped disc brake rotor type of throbbing from that drum. I found another drum on ebay and replaced that drum (a low mileage drum with a lot of "meat" left).
So....question 1): I have done a lot of brake jobs on drum braked cars and never ran into a "hot spot". What causes them? Is it a casting flaw?
question 2) Could I drill out the hot spot area and use the drum again? If I could, would I have to chamfer the hole on the shoe contact side?