Pull studs (also known as retention knobs) are critical components that secure a tool holder to a CNC machine's spindle. While there isn't a universal "part number" for all, they are classified by their design and taper size. Understanding the system and size your machine uses is the key to identification.
Here is a breakdown of the most common types, their associated numbers, and how to interpret them.
🏭 Major Pull Stud Types & Their Numbers
The table below outlines the most common standards. The numbers (30, 40, 50) refer to the taper size of the tool holder, and they are almost always explicitly stated in the part number.
| Standard | Common Variants / Sub-types | Typical Sizes | Standard / Origin |
|---|---|---|---|
| BT | Standard, Coolant-through | BT30, BT40, BT50 | MAS 403 (Japan) |
| CAT | ANSI, DIN, MAS (metric), MAZAK | CAT40, CAT50 | ANSI B5.50 (USA) |
| HSK | Type A, E, F, T, etc. | HSK50A, HSK63A, HSK100A | DIN 69893 (Germany) |
| DIN / SK | Type A, B, C, D (often with/without coolant) | SK30, SK40, SK50 | DIN 69872, ISO 7388/1 |
| ISO | Type A, B | ISO30, ISO40, ISO50 | ISO 7388-1, ISO 7388-3 |
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