CNC Threading and Machining Practice Test

Reaming is a finishing step that removes only a small amount of material to bring a hole to exact finished size with a smooth surface. Because the reamer must cut cleanly, you leave a small amount of stock after drilling so the reamer has something to engage and can size the hole accurately. About 0.005 to 0.010 inches is a typical amount to leave. It gives enough material for the reamer to cut smoothly and control tolerance, while not so much that it requires excessive material removal, which can cause longer cutting time, potential chatter, or distortion. If you leave less than this, the reamer may rub or produce a poor finish; if you leave more, the tool has to remove more material, which can affect straightness and finishing time. So the 0.005–0.010 inch range is the standard balance for finishing through reaming.