Lathes and milling machines are both used for cutting raw material, but they have very different ways of doing so. Lathes spin the material, whereas a milling machine uses a spinning tool for various cutting operations. To utilize either, you must know the differences between the two and what each is capable of.
Lathes create cylindrical parts using outside and inside diameter cutting tools of varying sizes and shapes. The material spins on a chuck while a tool cuts away material. The tool is secured on the tool post or in the tail stock.
A milling machine spins the tool to cut material that is held stationary in a fixture or a vise. Milling machines use cylindrical cutting tools, such as end mills and drills, to remove material to make a finished part.
The main tool used on a lathe is an insert cutter, which uses a removable tip to cut and shape the outside of material spinning in the chuck jaws. This type of cutting tool is not used on a milling machine. The milling machine's most commonly used type of tool is the end mill, which is placed in the spindle and spins at various speeds depending on the type of material being cut. End mills can be used in lathes, but they are usually used only in the spindle of a milling machine.
If you need to cut material that is cylindrical, you might choose a lathe. It is better at holding work, and cutting the material will be much easier because of the nature of the machine . You can drill only on center with a lathe, so if you need an off-center hole or to make straight cuts in metal, you will be better off putting that material in a vise or fixture and cutting it using a milling machine. Angled cuts, and anything that needs to remain non-cylindrical, will be better cut in a milling machine.
Setting up a lathe involves less precision, as the chuck itself will center the part for cutting. When installing the chuck jaws, make sure they are equidistant from the center. This will prevent any errors during the cutting.
To use a milling machine, you must measure the vise or fixture to make sure it is straight. To do so, use a dial indicator on the spindle and tap the vise until it is perfectly straight. Retighten the retention bolts and recheck for straightness, making whatever adjustments are necessary.