Rotary Tool Chuck Assembly for Multi-Size Hex Bit Clamping

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Solution Overview

Problem

Existing chuck assemblies for rotary power tools either suffer from the limitations of continuously variable chucks or are optimized for a single standard size, leading to inefficiencies in weight, size, manufacturing cost, and bit-changing time, especially when accommodating multiple standard hex-shanked bits with varying actual dimensions.

Innovation Solution

A chuck assembly with a rotatable collar and movable jaws, featuring oblique slots and threaded engagement, allows for securement of multiple standard-sized bit shanks by selectively engaging threads to accommodate different nominal sizes without requiring continuous adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a continuously variable chuck is used to accommodate multiple bit sizes, then adaptability is improved, but device complexity and weight increase

Engineering Contradiction:

Improveability to accept continuous range of bit sizesVSAvoidchuck assembly structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The chuck body is segmented into multiple discrete jaw positions, each configured for a specific standard bit size (1/4-inch, 3/8-inch, 7/16-inch). The jaws can be selectively positioned at different locations around the chuck body, allowing accommodation of multiple bit sizes without requiring a continuously variable adjustment mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The chuck assembly is designed with multi-functionality to accept multiple standard hex-shanked bit sizes using the same basic chuck structure. By providing multiple fixed jaw positions and allowing selective positioning, a single chuck can serve multiple purposes for different bit sizes, eliminating the need for separate chucks for each size.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If a single-size optimized chuck is used, then device complexity is reduced, but adaptability deteriorates

Engineering Contradiction:

Improvechuck assembly structureVSAvoidability to accommodate multiple bit sizes

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The chuck assembly incorporates dynamic elements including movable jaws that can be positioned at different locations around the chuck body, and a rotatable collar that allows selective engagement with different jaw positions. This dynamic capability enables the same chuck structure to adapt to multiple standard bit sizes without increasing fundamental complexity.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If continuously variable chuck is used, then adaptability is improved, but time to change bits increases

Engineering Contradiction:

Improverange of bit sizes acceptedVSAvoidtime required to change bits

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The chuck body pre-configures multiple jaw positions corresponding to different standard bit sizes before the bit change operation. When a bit needs to be changed, the user simply selects the appropriate pre-configured jaw position rather than adjusting continuously variable mechanisms, significantly reducing the time required for bit changes.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If continuously variable chuck is used, then adaptability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecontinuous adjustment capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Instead of manufacturing a complex continuously variable adjustment mechanism, the chuck body is manufactured with discrete, pre-configured jaw positions for standard bit sizes. This segmentation approach simplifies the manufacturing process, reduces production costs, and eliminates the need for precision continuous adjustment mechanisms while still accommodating multiple standard bit sizes.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables quick and secure attachment of tool bits with various standard hexagonal shank sizes, reducing complexity and time in bit changes while maintaining a compact design.

Implementation Method 1

A first plurality of threads is formed on the chuck body or the plurality of jaws, and a second plurality of threads is formed on the collar. The collar is rotatable about the central axis to a first orientation to engage the second plurality of threads with the first plurality of threads

Methodology Applied

Scientific EffectThreaded engagement: Screw

Implementation Method 2

The collar is axially movable along the chuck body without rotating the collar when the collar is in the second orientation

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12485493B2Chuck assembly for a rotary power tool

Publication Date: 2025.12.02 MILWAUKEE ELECTRIC TOOL CORP

AI summary

A chuck assembly for a rotary power tool includes a chuck body rotatable about a central axis. The chuck body has a plurality of slots, each oriented at an oblique angle relative to the central axis. The chuck assembly also includes a plurality of jaws, each movable along a respective one of the slots. The chuck assembly also includes a collar coupled to the plurality of jaws. The collar is selectively engageable with the chuck body such that, when engaged, the plurality of jaws are movable along the plurality of slots in response to rotation of the collar.