You don't always have to change speeds when you are drilling but you probably should. I leave mine set around 1800RPM when working with stainless steels for my bench top drills. I tend to drill big holes in heavy stuff in my floor stand drill press so I leave it around 800 RPM. I almost always change the speed on the big drill press to match this chart.
Print this chart out. Click on the small picture to get the large picture to pop up in another window. Right click the larger picture and print it out or save it and then print it out. Tape it on to the side of your drill press.
www.midwestknifemakers.com knife tutorials and reference charts and data for knife makers.