A lathe spindle is the area of the tool that actually holds the stock in place. When working with a metal working lathe, the spindle cannot do the work alone. At high speeds, the bar can have a tendency to wobble. This makes lines, scratches, and ribs in the stock that will not look good in the finished product. Because of this a spindle liner is a beneficial addition.
The most beneficial use for a spindle liner is with a CNC machine. These machines are worked with automatic precision that enables the tool to do the work from a computer program. The spindle liner keeps the stock bar in place without the worry of it moving.
Another great benefit of spindle liners for a CNC machine, or a regular metal working lathe is to be able to work with larger pieces of stock. The liner keeps things centralized on the lathe spindle so using larger stock will not cause excess vibrations or movement.
Metal or Poly
Spindle liners do not just come as one type. One of the great things about spindle liners is that you can buy a polyurethane product, or you can make your own. A basic project for many metal workers is to manufacture their own spindle liner for use in other metal working projects.