Indentifying the Headstock Spindle Thread Size of your Lathe

How to Measure a Lathe Headstock Thread

To fit any accessories to your lathe, you will need to know the headstock spindle thread size. Bear in mind, these can be manufactured in Imperial or Metric sizes.

1) Using an accurate ruler, or pair of callipers, measure the thread diameter (at the widest point).

2) Measure the thread pitch, also known as threads per Inch (tpi). If the thread is imperial size, count how many turns in half an inch and then double it. If the thread is Metric count as many turns as you can.

Examples

Imperial Size:

Metric Size:

If your lathe is 10 years old or less, it will almost certainly be one of these 3 sizes:

3/4” x 16tpi

1” x 8tpi

M33 x 3.5mm

Other less common thread sizes are: