No, this post has nothing to do with a song by the Byrds. Nor anything to do with Ecclesiastes 3:1-8 (the source of the lyrics for the song). Last week I promised a brief demonstration of what a metal cutting lathe does. So here we go!

For this demonstration I’m not really making anything in particular. I’m just demonstrating some of the types of cuts that are commonly done on the machine. The metal is just a little scrap of aluminum bar that was lying around.

I marked the direction the piece will spin with a Sharpie. That’s not normal procedure, just a visual aid so you can tell what’s going on. I then mounted it in the lathe.

With the lathe in “forward” the work will turn in the direction indicated.

Facing it off

If you look closely you’ll see the saw marks from a hacksaw on the end of the part. We’re going to cut off those marks so the end is smooth and flat. That’s known as “facing” the part. I will push the cutting tool into the center of the end of the work, and then retract the cross slide so the cutting tool moves across the face of the part to the edge.

You can see a curl of metal forming from the cut. That’s known as a chip. Also note the tool and toolpost are at an angle to the cross slide. That’s simply so that only the tip of the tool touches the work. If the whole face of the tool were in contact with the work it wouldn’t be able to cut very well.

It took a couple light facing passes to get the end entirely smooth.

Turning the diameter

Once I finished the facing, I moved the tool away from the work, shut off the motor so the work stopped spinning, and angled the tool back to roughly parallel to the cross slide.

The tip of the tool is just touching the work, and the dial has been reset to 0.

I then turn the cross slide until the tool just touches the work (note that the motor is still off, so the work isn’t spinning). Next, I rotate the dial so it reads “0”, so that I can easily tell how much metal I will be removing with each cut.

Note the chip of metal coming off the cutting tool. Also note the state of the arrow!

Having established the zero point, I used the cross slide handle to move the tool 0.010″ forward. I will move the tool toward the chuck, reducing the diameter of the work as I go.

My goal here was just to show how basic cuts are made, so I stopped there. Had I been making something in particular, I would have cut the piece to a specific length and diameter.

I hope this helped you understand what a lathe does. Thanks for reading!