Give me details of the rpm, grade of aluminum and approx feed rate. Are you useing a spotting drill to start or a center drill? Are you trying to drill a pilot hole? If you use a pilot hole it should NOT be bigger than the wide of the web on the larger drill.
For 6061 aluminum with a 1/2 inch drill I would run about 900 RPM with no pilot hole. My feed rate would be 4-5 inches per minute. You will have to back out to clear the flutes every 1/4 inch or so. |