How to Choose the Right Chuck for Your Lathe – Complete Guide
First, you need to know the maximum swing diameter of your lathe.
For example, if your lathe’s swing diameter is 320 mm (about 12 inches), the best chuck size would usually be 250 mm (10 inches).
You can also use an 8-inch chuck, but you should not use a 12-inch chuck.
Why?
In actual operation, when clamping a large workpiece, the jaws will extend beyond the chuck body. This means the rotating diameter of the chuck becomes larger than its outer diameter. Therefore, the chuck’s outer diameter must be smaller than the machine’s swing diameter.
Next, you need to identify the spindle nose type — the connection between your spindle and chuck.
You can usually find this in your lathe’s manual. However, some manuals list multiple spindle options for the same machine model, or your lathe might be too old and the manual is missing.
In that case, you can still determine which chuck type or adapter plate you need by following the method below.
Types of Spindle Noses
For both lathes and grinders, spindle noses are generally divided into three main types:
Plain (register fit), Threaded, and Short Taper (Camlock/Flange type).
Let’s focus on short taper spindles, which are the most common type on manual and CNC lathes.
They are further divided into three standards: A-type, C-type, and D-type.
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A-type spindles are common on CNC lathes.
They are fixed with hex bolts, and further divided into A1 and A2 — the difference is whether the mounting bolts are on the inner or outer bolt circle. -
D-type spindles use camlock pins for quick installation.
They are often found on conventional lathes. -
C-type spindles are fixed with a drive key plate.
This type is rare in North America, but if you happen to see one, feel free to share a photo in the comments!
Once you’ve identified whether your spindle is A, D, or C type, you can measure the large-end diameter of the short taper and the bolt circle (bolt center distance).
Then, by referring to a standard chart, you can confirm your exact spindle model.
If your lathe has a plain register fit or threaded spindle,
simply measure the register diameter, thread size, and bolt hole spacing —
then send this information to TOP-TOOL’s sales team, and they will help you choose the correct adapter flange plate.
Important Notes
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A chuck with a short-taper back plate can be mounted directly onto your spindle.
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If your chuck has a plain back, you will need a flange plate.
After installing the flange on the spindle, you should turn (machine) the outer register diameter and face of the flange to ensure mounting accuracy before installing the chuck.
| Spindle Nose Type | Large-End Diameter of Short Taper | Bolt Circle (Center Distance) | Bolts |
|---|---|---|---|
| A1-5 | 82.563 | 104.8 | 3-M10 |
| A1-6 | 106.375 | 133.4 | 6-M12 |
| A1-8 | 139.717 | 171.4 | 6-M16 |
| A2-4 | 63.513 | 82.6 | 3-M10 |
| A2-5 | 82.563 | 104.8 | 6-M10 |
| A2-6 | 106.375 | 133.4 | 6-M12 |
| A2-8 | 139.719 | 171.4 | 6-M16 |
| A2-11 | 196.869 | 235 | 6-M20 |
| A2-15 | 285.775 | 330.2 | 6-M24 |
| A2-20 | 412.775 | 463.6 | 6-M24 |
| C3 | 53.975 | 75 | 3-M10 |
| C4 | 63.513 | 85 | 3-M10 |
| C5 | 82.563 | 104.4 | 4-M10 |
| C6 | 106.375 | 133.4 | 4-M12 |
| C8 | 139.719 | 171.4 | 4-M16 |
| C11 | 196.869 | 235 | 6-M20 |
| C15 | 285.775 | 330.2 | 6-M24 |
| C20 | 412.775 | 463.6 | 6-M24 |
| D3 | 53.975 | 70.6 | 3-M10*1 |
| D4 | 63.513 | 82.6 | 3-M10*1 |
| D5 | 82.563 | 104.8 | 6-M12*1 |
| D6 | 106.375 | 133.4 | 6-M16*1.5 |
| D8 | 139.719 | 171.4 | 6-M20*1.5 |
| D11 | 196.869 | 235 | 6-M22*1.5 |
| D15 | 285.775 | 330.2 | 6-M24*1.5 |
| D20 | 412.775 | 463.6 | 6-M24*2 |