End Mills with gripping surfaces along the shank can prevent tool slippage and improve rigidity for aggressive roughing passes in aluminum machining. So many of us have lost parts from tools slipping out of their holders. The reassuring whir of chips being made gives way to a screech and a thud, and we jump into damage assessment, hoping that the part is salvageable and knowing that it likely is not. Tool slippage is becoming more and more common as feed rates that were unthinkable ten years ago become commonplace. Advanced cutting tools like the RobbJack end mill modeled here are capable of removing material at an incredible rate. However, toolholding also has to be up to the task if the user wishes to avoid tool slippage. Advanced machining technologies are drastically increasing feed rates for manufacturing, and this is especially prevalent in aluminum machining. The combination of more powerful machine tools and more aggressive machining strategies have pushed the material-removal rates towards levels that would have been unthinkable not long ago. Unfortunately, these high rates of material removal can put an enormous strain on the tooling. Even light metals such as aluminum...