In his 1995 article in Fine Woodworking Lon Schleining writes, “I don’t use slip knives. I use only wing cutters, safety cutters or router bits.”  It’s a very good article, especially regarding safety.  I know what a wing cutter is, and I know what an insert cutter is, but I don’t know what a slip cutters or a safety cutters are. Please help me to clear up the distinction.