i was picturing a larger steel angle iron ,you should be able to do that quite easily with a nice set of alum step jaws , use an endmill to square up the inside a decent 3/4 endmill with a .25 stepdown ,at the right speed and feed you should have no problem , if chatter is a problem you can under cut the flutes so only .3 is in contact with the surface , or run a stone across the cutting edge to dull down the tool , a sharp tool isn't always the best and can actually cause the chatter |