Fly Cutter Dangers

Many folks don't have chassis punches or large metal hole drills, so they choose to use a fly cutter.

The old time DIY articles mention these being part of a well stocked radio repair tool kit. As far as my opinion, toss them in the scrap pile. Just too dangerous to use in an electric drill.

 Basically it is a drill bit holder with an arm coming out of it with a hardened metal "bit" that is adjustable to cut a hole in a chassis.

They are " safest " being used with a drill press and the metal you are cutting MUST BE FIRMLY CLAMPED DOWN, REPEAT-MUST BE CLAMPED DOWN!
DO NOT ATTEMPT TO HOLD METAL IN YOUR HAND!!

If the metal is not clamped down firmly the fly cutter has a tendency to "stick" in the metal and grab it and rotate it around like a lawn mower blade.
  (Sadly I know this from first hand experience, a trip to the ER and a 4" gash in my hand. I was lucky! Any deeper and I would have severed tendons and ligaments!).

If proper safe guards are used they can work. Not the cleanest hole though.

As far as using in hand drills, IMHO, forget it Way, way to dangerous.

While expensive, chassis punches or metal hole saw kits are much safer and cheaper than a trip to the hospital emergency room, or the loss of fingers or a hand.

Even with metal hole saws, it is best to clamp down the chassis and use with a drill press.