Another trick that clears chips and conserves material when cutting disks for bosses, is to "drill" so that the hole saw is tangent to a material edge, or the previous hole, and the chips just spill out. Just today I cut 8 @ 2"D x 1/4" mild steel bosses in less than 15 min total. This amounts to going through 2" of steel with a 20 year old hole saw that has been through many inches of steel and still going strong. The drill press was set for 270 RPM.