Buying a Lathe — What You Should Know
There are a variety of uses for lathes, such as metalworking, woodturning, and metal spinning to name a few. Some would call a lathe the “mother of machine tools.” It is the first machine tool that lead to the invention of other machine tools. With so many different types of models to choose from with different specs and prices, it’s easy to find yourself in a situation where you may be looking for some useful guidelines to help you with your choices.
The Modern Lathe
One of the many things lathes are useful for is woodturning. As consumers, we use a lot of products made of wood where lathes are used in creating them. But more recently, lathes are being used as a tool to create art made from wood. And as a result, many machine shops are finding a need to add these machines to their arsenal of equipment.
You Get What You Pay for
You’ll find a lot of inexpensive lathes out there that are similar in appearance and seemingly give you a lot of bang for the buck. However, these are entry-level machines and may be a good choice if you’re just starting-out, but the more work you do and the more demanding your projects become, you’ll eventually find these lower-priced machines to be rather limiting. The fact is, you get what you pay for.
“She’s So Heavy”
John Lennon couldn’t have said it better! When it comes to machine tools, weight is a very important factor. The heavier your machine, the more rigidity and vibration-free performance you’ll have. You don’t want your workpiece to get out of balance. The weight of your machine alone will minimize vibration and help greatly in producing error-free workpieces.
A cast iron lathe (which is heavier) is always better than a fabricated one but will be more expensive. You will be spending a lot of time machining pieces so you’ll want a lathe that’s solid, heavy and durable, providing the most rigidity possible. You will find that it’s well worth the money you pay. Kent USA’s full range of lathes offer not only precision but also stability.
Swing and Bed Measurement
The Swing measurement is the maximum diameter of material that can be cut or machined on a lathe. You measure from the bed of the lathe to the center of the spindle and then double that measurement. The Bed measurement is the maximum length of the workpiece that you can turn being determined by the distance between centers. These are things to consider when purchasing your lathe, the length of the Bed and the amount of Swing measurement.
Foundation: Floor or Bench-mounted
For professional applications, you’ll need a rigid, heavy-duty, floor-standing turning lathe. But for the hobbyist who is interested in projects like woodturning, a much smaller bench-mounted lathe will do. Bench-mounted lathes will bolt down on any solid and secure surface. The advantage of bench-mounted lathes is that you can adjust the center height to your liking.
Types of Stands and Tool Storage areas
For smaller table-top lathes, there are some options that are available from different manufacturers. You can buy a leg stand made of folded steel or perhaps a tube design. Some are available with an added tool shelf to store your tools. You can also craft a wooden bench, which is better for absorbing unwanted vibration. Having your tools stored in a shelf under the lathe will provide more weight and rigidity, which will further help to reduce vibration.
The lathe bed, typically, is made from cast iron bars and connects to the headstock, while allowing the tool carriage and tailstock to move parallel with the axis of the spindle. It must be strong enough to support the tailstock and tool rest without any bowing or bending, while allowing for free movement of both. The bed must also allow shavings to fall through.
A cast iron headstock is the core of the lathe and needs to be heavy, solid and rigid to turn large workpieces. On the other hand, fabricated headstocks, generally, are not heavy enough to machine large turning projects. The spindle is attached to the headstock. Regarding the spindle, a good distance between the spindle bearings is essential to have the most rigidity in the spindle. Spindle bearings that are close together can cause a lack of rigidity especially on larger diameter work so it’s better to have spindle bearings that are spaced further apart.
Higher quality spindle bearings are sealed ball races or tapered bronze-sleeved bearings. However, tapered bronze-sleeved bearings provide better support than ball races but will require periodic adjustment. If set up properly, the spindle is supported over a greater length giving consistent, level, vibration-free performance.
A headstock that can swing around at right angles has some special advantages over one that is permanently fixed in line with the bed because it allows you to work with the tool handles away from the bed and position the workpiece at different angles.
The Headstock Spindle
The spindle is a rotating axis which supports the chuck where the tool is mounted. It is the heart of the headstock. It’s best to have a spindle with a standard sized thread to support a wide variety of accessories.
There are two types of tapers: self-holding and self-releasing. Morse tapers are of the self-holding category. It is very important to have your lathe equipped with Morse tapers in both the headstock and tailstock so you will not be limited to just using your lathe’s original fittings. Morse tapers are typically used for lighter loads and have three types of ends:
- Tang, to facilitate removal with a drift
- Threaded, to be held in place with a drawbar
- Flat, no tang or threaded section
With Morse tapers, spindle keys are not required.
Lathe Motor and Drive
On a smaller lathe the motor should be no less than 1/3 horsepower. However, lathe motors with more horsepower will give you greater range, flexibility and means to machine larger and more complicated workpieces. The motor is equipped with a three or four-step pulley to give more speed variation. And the newer, more efficient flat poly V type belt gives a steadier drive with less vibration.
You are always better off buying a better-quality lathe because in the long run, it will last longer and you will spend less money replacing parts that will wear out more quickly as is the case with less expensive models.
Electric Speed Controls
Higher-end lathes come equipped with an electric speed control. This feature provides a great range of speed by just turning a knob. The latest technology offers a three-phase motor. Advanced features include memory that can store your selected speeds. They will also sense problems and if necessary, will immediately turn off the lathe.
Your switchgear box should be easy to reach and unobstructed by large workpieces. These switch boxes are also available in magnetic cases so you can move them around your lathe conveniently as you are working.
Throw it in Reverse!
Reverse capability on a lathe motor is great for sanding and safe for between-centers projects. But use caution if you’re working on a faceplate when your motor is engaged in reverse as the faceplate may become detached. Be sure your lathe has a faceplate locking mechanism.
A very important feature of the lathe is the tailstock providing support to the rotary axis of a workpiece. It also holds tools used for machining holes in workpieces. It must be allowed to slide freely and lock firmly in place on the bed. The tailstock is moved along its ways to the position where it will be needed.
A tool rest supports a lathe’s cutting tools. A very important part of a lathe, it must be quickly and easily adjustable. Some have a clamp and lever locking system under the bed of the lathe, while others use a cam lock that is easier to use because it is accessed from the front of the lathe. Something you should consider before your purchase.
The tool rest is made of cast iron and once locked into position, there must be no movement. The heavy-duty, rigid, cast iron construction ensures vibration-free performance.
What’s Right for You?
Now, you know enough about lathes to make an informed decision in your purchase. But what type of lathe will best suit your needs?
For smaller projects like woodturning, you may not want to invest in a swinging head lathe. However, if you are working a lot on bowl turning projects, a swinging head lathe might be the way to go.
If you’ll be machining a wide variety of workpieces, you’ll want to buy a lathe that will turn the largest diameter possible.
If you are machining only occasionally, working on simple projects, then choose a basic, less expensive model. But as your machining needs grow, you may find the need to purchase a larger machine with the extra weight, rigidity and power you’ll need.
The higher-end lathes will give you the power, flexibility and ease to turn your workpieces more quickly and efficiently, and will allow you to make deeper cuts. Kent USA offers both engine lathes and precision lathes for starting and experienced machinists.
A Final Thought:
Buying a lathe is a big investment. Look at the big picture and determine what will be best for you long term, down the road. It may be better to buy a larger, heavier, more rigid machine now so you can save money on replacing parts and upgrades in the future.