Spindle Liner FAQS

Why are JF Berns Spindle Liners better than other liners?

The JF Berns Company has been designing and manufacturing spindle liners for over 25 years. That experience has enabled us to gather information on almost every Lathe make and model. For this reason we do not require as much information and we know what questions to ask. The end result is you get the spindle liner faster and will usually fit the first time. Also, after manufacturing over 100,000 spindle liners, we have learned how to make the best liners possible. Sized perfectly, straightened to within 0.005″ TIR, size and part number permanently engraved, easy out system included as well as all the mounting hardware. Fast and Easy! The JF Berns Company also provides all the options and accessories to enable you to have one source to meet your needs. Extensions on liners, quick change option, spindle liner racks, coolant collector extensions, molded urethane cores, bar supports, draw tubes & more!

What is a spindle liner and do I really need them?

The basic components of a lathe spindle are the chuck, the draw tube and the hydraulic actuator. The draw tube is the connection between the hydraulic actuator on the back side of the spindle and the chuck on the front side (machining side). The ID of the draw tube is maximum bar diameter capacity of the lathe. In a lathe, the chuck, draw tube and bar stock all rotate together at high RPMs for stationary cutting tools. If you are running bar stock whose diameter is less than the draw tube ID, then there is a lot of clearance between the bar stock and the draw tube. Since the bar stock is clamped only in the chuck, any bar stock that extends back into the spindle will ‘whip’ as the RPMs of the spindle are increased. This ‘bar whip’ will cause vibration which will reduce the quality of the machining, can damage the spindle and worst case can bend the bar up causing severe injuries and even death. The spindle liner is sized so that it has the proper fit in the ID of the draw tube and then also has the proper clearance on its ID over the bar stock OD. This will virtually eliminate the bar whip and allow the lathe to run smoothly and safely.

Do I need a liner for each bar stock diameter?

Yes, unless the difference in bar stock diameter is less than 0.010″, a spindle liner is required for each bar stock diameter. While it is possible to run bar stock with a lot of clearance, you will have the same issues with ‘bar whip’ as you do when you do not use spindle liners at all. In the overall scope, spindle liners are reasonably priced and are well worth the investment to ensure that your lathe is able to safely and accurately machine the bar stock.