# Pull studs

Retention-knob geometry, thread compatibility, installation torque, drawbar force and manufacturer-specific service limits.

Reviewed: 2026-11-02

Tags: tooling, toolholding, spindle-interfaces

## Identity and function

Haas **04-0201** and Briney **B111-22** both list **5/8–11** threads and **45°** heads. Their head diameters are **0.590 in** and **0.740 in**, a **3.810 mm** difference. Compare head and neck geometry, installed projection and coolant provision against the machine's requirement. Installation torque and axial drawbar force are separate checks. [Haas 04-0201 dimensions](https://www.haastooling.com/p/04-0201), [Briney standard retention knobs catalog](https://brineytooling.com/wp-content/uploads/2016/11/Briney-Catalog-1-120-smaller.pdf).

A pull stud, or retention knob, is the connection gripped and released by the spindle drawbar during tool changes.

## Geometry: why the thread is insufficient

These two products share a thread designation and a 45° head angle but have different head and neck diameters. Dimensions below are the manufacturers' own labels, not an assertion of interchangeability. Haas identifies its product specifically for Haas CT40/SK40 machines; Briney catalogs its part under ANSI-style V40 retention knobs. [Haas 04-0201 dimensions](https://www.haastooling.com/p/04-0201); [Briney standard retention knobs catalog](https://brineytooling.com/wp-content/uploads/2016/11/Briney-Catalog-1-120-smaller.pdf)

| Product | Thread | Head diameter | Neck diameter | Head angle |
| --- | --- | --- | --- | --- |
| Haas 04-0201, CT40 TSC pack | 5/8"-11 | ØK = 0.590 in | ØN = 0.393 in | 45° |
| Briney B111-22, V40 ANSI style | 5/8"-11 | C = 0.740 in | B = 0.490 in | 45° |

**Worked comparison:** head-diameter difference = 0.740 − 0.590 = 0.150 in, or 0.150 × 25.4 = 3.810 mm. Identical thread and angle therefore leave a substantial dimensional difference at the gripping head. This calculation compares published nominal dimensions; it does not establish a permissible mismatch or a drawbar engagement margin.

Head profile and angle, head/neck diameters, projection from the holder, shoulder seating and threaded engagement all influence the physical fit. A label such as CAT40 or BT40 describes a holder family, not every detail of the machine's required retention knob. Haas's RD0074, revision B, August 2026, explicitly identifies an incorrect pull-stud size or type as a source of spindle damage. [Haas toolholder and pull-stud specifications](https://haascnc.com/service/troubleshooting-and-how-to/reference-documents/tool-holder-and-pull-stud-specifications.html)

## Installation torque is not retention force

Installation torque seats the threaded stud in the holder; spindle drawbar force is the axial pull retaining that assembly. Their units differ: N·m or ft·lbf for torque, N or lbf for force. KEMMLER publishes installation recommendations of 20 N·m for SK/BT/ISO30, 50 N·m for size 40 and 100 N·m for size 50. These are that manufacturer's recommendations, not universal values for every knob with those taper numbers. [KEMMLER tightening data](https://www.kemmler-shop.de/en/Products-Shop/Pull-studs/Technical-information/)

JM Performance Products describes holder expansion from excessive tightening and identifies worn components, broken drawbar springs and gripper adjustment as possible causes of low drawbar force. A correctly tightened stud does not prove that the drawbar develops the specified force. [JMPP product-guide insert, p. 2](https://www.jmperformanceproducts.com/user/files/literature/Product%20Guide%20Insert.pdf#page=2)

Haas RD0067, revision D, April 2026, lists 1,460–2,300 lbf for the 12,000 rpm row in its 40T VF/VM/EC/UMC/GM (3-axis) group. The separate 40T DM-series 12,000 rpm row gives 920–1,420 lbf. Thus even one builder's 40-taper spindles do not share one force range. [Haas drawbar-force reference](https://haascnc.com/service/troubleshooting-and-how-to/reference-documents/drawbar-force-reference-table.html)

**Worked torque example, explanatory synthesis:** a 50 N·m setting corresponds to a perpendicular 200 N force at a 0.25 m lever arm because T = F × r = 200 × 0.25. That 200 N is a force on the wrench, not the drawbar's axial retention force. Thread friction, seating friction and geometry prevent this lever calculation from determining stud preload.

## Coolant and service life

Haas 04-0201 includes a through-hole for through-tool coolant. That passage is a product feature; it does not establish pressure rating, spindle-seal compatibility or installed coolant capability. Briney separately lists B111-22 with a coolant hole and B111-23 without one despite their otherwise matching listed dimensions. [Haas TSC product description](https://www.haastooling.com/p/04-0201); [Briney retention-knob table](https://brineytooling.com/wp-content/uploads/2016/11/Briney-Catalog-1-120-smaller.pdf)

Haas's mill-tooling maintenance page, updated November 30, 2018, calls for examination of damage, wear and torque. It gives an approximate 6,000–8,000 operating-hour service life and lubrication intervals of monthly for ordinary use and weekly with TSC, while qualifying those intervals as average-user guidance. [Haas mill-tooling maintenance](https://haascnc.com/service/troubleshooting-and-how-to/how-to/mill---tooling---maintenance.html)

JMPP recommends replacement every three years under normal wear based on a 40-hour work week. It also specifies replacement for damaged, nicked or scratched knobs, and attention to O-rings with wear, swelling, flattened areas or cracks. These condition findings can precede a scheduled replacement date. [JMPP service guidance, p. 2](https://www.jmperformanceproducts.com/user/files/literature/Product%20Guide%20Insert.pdf#page=2)

**Interpretation:** calendar age and operating hours are different service measures. Neither cited schedule establishes a universal fatigue life or permission to retain a damaged component until its nominal interval expires.

## Coverage limits

This article covers selected toolholder-retention products, not workholding pull studs or every spindle interface. It does not supply complete manufacturing tolerances, universal torque or lubrication instructions, or a machine-independent replacement interval. Installed knob identity, drawbar geometry and condition, coolant sealing and the applicable machine/holder instructions remain assembly-specific.

The Haas service-document revisions are stated above. The Haas product page, KEMMLER technical page, Briney catalog and JMPP insert supply no established issue date for this reference. Briney's PDF contains production-layout timestamps, which are not treated as its issue date. URL upload dates and crawl dates are not editions. The reviewed date records this article's research review.

## Related reference

[Cutting tools and tooling references](../index.md)