What Is Lathe Swing: Clear Definition And How To Measure!

Last Updated on May 7, 2022 by Charles Wilson

The swing of a lathe is actually one of the most important parts of the device. And this is because the swing represents how big or small a workpiece can be used and worked with on a lathe.

The lathe is basically used to rotate objects so that you can do cutting, sanding, and drilling. However, a lot of people are a bit confused about lathe swing. They don’t have a proper idea about it. Don’t worry, that’s what this article is about.

Now, both wood lathe and metal lathe have a swing, and the swing refers to the maximum diameter of a workpiece that can fit into the machine. To clear all your confusion regarding lathe swing, scroll ahead and read on.

Definitions of lathe swing

"a piece of round wood bowl blank is attached with the headstock of a lathe"

Swing on a lathe machine measures the maximum diameter of a workpiece a lathe can handle without hitting the machine.

The first type of lathe swing is called swing over bed.

Swing over bed indicates the maximum diameter of a workpiece that can be rotated over the bed of a lathe without hitting it. To measure swing over bed, measure from the center of the spindle to the top of the bed and double the result.

There is also a second type of swing called swing over carriage.

Swing over carriage is the maximum diameter of a workpiece that can be rotated over the carriage (also known as the lathe saddle) without hitting it. To measure swing over carriage, measure from the centre of the spindle to the top of the carriage and double the value.

The swing and distance between the centers will determine the capacity of a lathe which means the maximum size of the workpiece you can work with.

This is a piece of important information to have as you might be in a tight fit if the lathe does not allow you to work with pieces too big.

This situation can occur, say, for example, you buy a lathe with a 10” diameter, however, you will not be able to fit an object of 10” diameter into the machine because the bed way would work as an interference.

The object will be in a tight situation, and it will be more difficult for you to work with it. Get it?

How to measure the swing and size of a lathe

The measurements, in this case, are of great importance and significance, as your work will depend on these numbers and figures. If you get the sizes wrong, you will be in a slight pickle as the item you are going to operate on will be too big to fit into the machine.

Swing is not the only measurement that you need to be concerned about; the distance between the lathe center is equally significant as that distance determines what length of item can be fit into it.

Okay, so measuring the swing is actually not at all a difficult task by any means.

All you are going to have to do is take a measuring tape and figure out the distance between the center of the spindle and the bed way, whatever figure you get just double that, and you will get the swing.

So, if you measure the distance to be 5”, which is the radius, after doubling it you get 10”. That is the swing of the lathe. But as I mentioned before, you have to keep in mind that it is not actually possible for you to fit an item or object into the lathe which has a diameter of 10”.

Even if you are able to fit it in, you will face a very hard time trying to work with it as you will be allowed less space to work and might find it hard to reach every part.

Some extra things you need to keep in mind

When buying a lathe machine, you should keep a few things in mind so that you do not have problems using it. Sometimes, you will see that the labels provided by the manufacturers of the lathe are not correct, or measurements might be a bit off.

In that case, you are gonna have to go through the step of returning and replacing it. Often the metric system used to do the measurement might not be the same one.

You might be looking for a 12-inch swing, but end up buying one with a 12-cm one. They are not interchangeable as the difference in the diameters is vast.

So, be careful and mindful when you go out to buy one. Sometimes, you will see that a few companies consider that to be the real swing of the lathe, in that case, you are going to have a much smaller and tighter workspace in terms of diameters.

And the last thing you have to keep in mind when you consider buying a wood lathe, or even a metal lathe, in particular, is the swing over the carriage. This is where your tool will sit.


So that’s it for today. We really hope that now you don’t have any confusion regarding lathe swing. If you still do, let us know in the comments section. We will be happy to help!

6 thoughts on “What Is Lathe Swing: Clear Definition And How To Measure!”

    1. Hi Jeff, how are you doing?

      The Gap is a portion of the bed that can be removed to accommodate larger diameter work. If you have a gap bed lathe, the lathe will have both figures.

      This is a removable piece of bed just at the chuck end. They vary in length depending on the model and size of the machine. Many smaller machines don’t have them.

      Sorry for the late response, I didn’t notice. Hope you and your family stay well.

  1. I think I know what you mean with the swing
    is a bench lathe the best for beginers
    money not a problem can buy cheap or dear

    1. Hey there Fred! Well, it’s a bit unclear what you are trying to say here.

      This post is about how to determine the swing of your lathe by measuring the distance between the mounted workpiece and the bed.

      1. I’m looking at a Grizzly 9729 for doing home gun smithing jobs. I understand what seeing is, thanks to you, but have a question about the 31″ center it claims to have. Does this mean I can put a 31″ round stock in it to cut a barrel piece to length? Thanks for your help!

        1. Hey there Alan. Are you talking about this version of the Grizzly milling combo? That’s a great machine.

          No. It means that the maximum distance between two dead centers is 39”. But you can’t turn between dead centers.
          You have to add something to hold your work, even a carrier takes a surface plate and that will reduce the 39”.
          And a 3 or 4 jaw chuck and you reduce the max length even more.

          Between centers usually means a center in the headstock without the chuck and one in the tailstock. Meaning the work would need to be turned between the centers with a lathdog or something similar.
          A chuck then decreases the overall turning length at least in my experience.

          I hope it helps. Stay sharp and healthy with your family.

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