The two major types of wood lathes, fixed speed and variable speed, follow the same concept as variable speed and fixed speed drills. The actual speed of the rotating spindle on a variable speed lathe can be increased or decreased. This allows you to control the project, use different tools and achieve different cuts. It can also help inexperienced wood turners improve their skills and gives them the chance to make different types of projects.
Variable speed wood lathes were invented when the need arose for different speeds to make all types of objects. At first the variable lathes were large and the idea was used in industrial sized lathes, but as technology advanced, companies were able to produce smaller variable speed lathes for the hobby turner as well as the industrial company.
A variable speed lathe has several features that make it a precision machine. Most notably are digital "speedometers" that tell you how fast the spindle is spinning. Swivel head stocks can rotate at different angles and allow what is called outboard turning, off the main frame of the lathe. Other features include interchangeable chucks, forward and reverse for different types of turning techniques, and solid steel construction.
A variable speed lathe typically will have some kind of gauge, switch or knob that adjusts the speed of the spindle. You can also tell a variable speed lathe by reading the description to see if there is a speed range, such as 5,000 to 15,000 rpm. In addition, variable speed lathes can have different types of speed drives. A common one is electronic speed control, which means the variable speed is controlled electronically, or by wattage supplied to the drive system, rather than by a mechanism of gears or a clutch, which is not very common.
Variable speed lathes come in all sizes. The smallest can fit on a workbench and is no more than 18 inches long. Smaller models are not the most powerful, but can turn at anywhere from 1,000 to 10,000 rpm or more. They are electronic speed varying, with many features of larger lathes, like interchangeable chucks, locking spindles and sometimes rotating heads. Larger variable speed lathes can be over 6 feet long and 4 feet high. These shop lathes are used by professionals and hobby turners. Even larger lathes can be over 8 feet long and up to 20 feet long. These are industrial lathes for turning large poles and other objects.
When buying your own variable speed lathe, consider how much versatility it gives you. You must have a lathe that is large enough to fit the biggest project you want to complete. It also needs to be able to turn bowls, long dowels and other projects you are interested in. Some lathes have a large speed range as well. This will give you more control and can offer more precision. If you only want to turn small projects, it makes sense to buy a smaller lathe, but make sure it allows you to turn everything you are interested in turning.