Although more commonly recognized on the milling machine, collets are used on the engine lathe almost as frequently. Being a skilled lathe operator requires the ability to make good productive decisions. These decisions will pertain to the methods and processes used to manufacture parts.

The collet system is extremely useful when there are many small parts that need to be machined. Specifically if these parts are less than an inch in diameter and require fine concentricity. CNC machinery sometimes uses the collet system in connection with an automatic bar feeder, enabling the machine to run virtually nonstop, with minimal operator intervention. This video shows how a collet with a depth stop can be used to very rapidly face all of the metal* plugs to equal size.

The most common collet found on the lathe is the 5C style collet. The 5C collet has a short tapered head and narrow body with 3 longitudinal slits along the front part of the head and body. Threaded at one end, a drawbar or other device is threaded onto the collet and the collet is pulled inward into the matching taper of the collet holder. This pulling action closes the collet chucking faces around the work and grips it with adequate force to perform machining operations. Collets can generally be turned at a higher RPM than a standard chuck because the collets are lighter and smaller, having less weight on the spindle. This is a useful feature for machining fine shafts or spindles or other small, light duty pieces. The most common danger is not having the collet grip tight enough causing the part to come loose.

label: lathe collet, C5, drawbar, collet chuck, collet variations, machining tricks