A reamer is a rotary cutting tool used to enlarge a previously drilled or bored hole to a high degree of accuracy and smooth finish. Reamers are made from heat treated steels or hard materials like tungsten carbide and diamond. There are various types of reamers including straight, hand, machine, rose, shell, tapered, and combination reamers. Reaming is performed on a lathe by mounting the workpiece and drilling or boring the hole slightly undersized, then mounting the reamer and slowly feeding it into the hole while applying cutting fluid to enlarge the hole to the final size.