Reducing Lathe Vibration, Part 2 - Problems with Tools
Most of us, especially those with smaller lathes, have experienced the frustrations caused by vibrations when turning with our wood lathes. There are a wide variety of factors that can cause vibration...here are some tips for reducing the problem. In this second part of our two part series about lathe vibration, we're going to cover problems that are caused by the lathe itself, rather than the user.
Improper mounting -
For smaller lathes that must be mounted to a workbench or stand, care should be taken to effectively immobilize the lathe. Always make sure to bolt (not screw or nail) down the lathe to your bench. Screws and nails are notorious for working their way out of the surface they've been put into over time due to the vibrations produced during turning. Bolts will typically stay put, and using nylon lock nuts to secure the bolts will help ensure the best long-term results.
Low quality or inexpensive lathe stands -
All lathes, whether they come with their own stand, or have been attached to a bench or shop-made stand, must be setup up correctly. Most smaller and less expensive lathes that come with stands have stamped steel legs. These stands are somewhat flimsy by nature, and need additional stabilization. It's a good idea to permanently attach these stands to the floor, and to add additional cross-bracing between the legs of the stand to reduce swaying during turning. Adding weight to the stand will also help. Building a container between the legs of the stand and adding sand or concrete will help reduce vibrations, as the additional weight requires more vibrating force to cause it to move.
Improperly leveled stands -
Whether you have a heavy cast iron stand, or something smaller with less weight, the base of your stand needs to be properly leveled. Most factory built stands will have leveling legs pre-installed. If your stand does not have leveling legs, then shims should be used. If even one leg is not properly resting on the floor, the lathe will produce a rocking motion. Even if this is slight, it can still cause issues with vibration, whether your stand is heavy-duty or relatively lightweight. If you haven't made sure that your lathe stand is properly leveled, then it is worth the time to make it right. If your lathe was properly leveled, make sure to check it at least once per year (or more, depending upon how frequently it is used).
Worn bearings -
Over time, the bearings in a lathe's headstock will become worn. As the bearings wear down, the portion of the headstock to which your wood is mounted will begin to move around slightly from side to side. Once this begins to happen, you'll find that it becomes more difficult to properly re-center pieces on your lathe (for example, when your switch from cutting the inside of a bowl to the outside, or vice-versa). Really heavily worn bearings will usually begin producing a loud squealing noise and are easy to detect, but partially worn bearings require manual inspection. Check your bearings by grabbing the threaded screw coming out of the headstock. Move this part from side to side. If there is any movement, then your bearings are most likely worn and will need replacing. Bearing replacement is usually not a simple procedure, so you may want to check with the manufacturer to see what recommendations they have for replacing worn bearings.
Improperly tightened drive belts -
Drive belts do not usually cause major problems with lathe vibration, but they can cause some minor issues. Over tightened belts can put excessive force against the shaft which turns the moving portion of the headstock, which eventually will cause premature failure of the bearings. Under tightened belts can cause more of an issue. If the belt starts to slip during turning, this can cause the lathe to speed up and slow down, which can cause excessive vibration especially at higher RPMs. Check your lathe owner's manual for specs on belt tightening. If none are available, tighten your belt until it can be deflected in or out by about 1/8"-1/4" with moderate pressure from your fingers.