I have a toolroom mill (open model, 4000 rpm) and am running a program that is doing a lot of pocketing and profiling in 6061 aluminum with a 1/2 inch, 3 flute, crest cut (roughing and finishing) tool steel end mill. MasterCam is telling me to run it at about 3000 rpm and 24 inches per minute. I am running it at 3500 and 35 inches per minute and the spindle load is peaking at 105% in some parts of the program. Is it possible to keep increasing speed and feed as long as the spindle load doesn't get out of hand? Of course I could experiment, but I am one of those 'stand on the shoulders of giants' types. Thanks.