Alvord Polk 827-0 Solid Carbide Reamer, CNC (Short) Length, Straight Flute, Round Shank, Uncoated Finish, Size: 1/4 Inch Oversize Straight flute reamers are recommended for general purpose reaming to make minor enlargements to preformed holes with a very precise size and circularity Straight flute reamers are good for use in through or blind holes without interruptions such as keyways (through holes extend through the entire workpiece, while blind holes do not) CNC length tools are generally shorter than other machine tools. The shorter length makes for a more rigid tool, which minimizes vibration at the higher rpms available with CNC machines Round shank tools are cylindrical and should be held in a good-quality toolholder in order to prevent the reamer from slipping in high torque applications, which can cause tool freeze, loss of accuracy, and tool damage Carbide resists abrasion and high cutting temperatures. It can run at higher speeds and is harder than high-speed steel