I recently picked up a great hole cutter/punch at a flea market in my town. It's made by Greenlee and is called a Ball Bearing Knockout Punch. I paid $5 for it but I'm sure it costs alot more in the store. I've used it to punch holes for putting ignition key assemblies on mini's and snowblowers and for fabrication of some air breather parts on a small engine. This thing works great. First you drill a 3/8" pilot hole insert the bolt portion of the tool, thread on the cutting head tighten it down by hand and then take a wrench and begin to tighten it until it punches though, very simple and effective. It doesn't bend or distort the piece of metal that you're working on. The hole is clean and crisp with no need to file any rough edges. Well worth the investment. It does only have four different size holes you can cut 7/8", 3/4", 1" and 1 1/4".:thumbsup: