A-Frame Bracket With Diagonal Bracing for Wobble-Free Joints

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Solution Overview

Problem

Existing A-frame structures, particularly those using metal brackets, suffer from wobbling and rocking due to inadequate bracket designs that fail to provide rigid connections between lumber elements, leading to instability and discomfort during use.

Innovation Solution

A one-piece bracket design with integral diagonal bracing and L-channel flanges featuring slotted holes ensures immobile connections between the beam and leg timbers, using bolts to secure them tightly against perpendicular planes, allowing for shrinkage compensation and enhanced structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If multiple fasteners are used to secure lumber to bracket, then the connection strength is improved, but the wobble and range of play increase due to soft wood deformation

Engineering Contradiction:

Improveconnection strengthVSAvoidstructural stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The bracket is divided into multiple functional components: a main body portion, a diagonal brace portion extending at approximately 45 degrees, and perpendicular flanges. This segmentation allows each portion to specifically address different aspects of the connection problem, with the diagonal brace providing lateral stability and the flanges providing bearing surfaces for fasteners.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention adds a diagonal dimension to the traditional rectangular bracket design. The diagonal brace portion extends from one corner of the main body at approximately 45 degrees, creating a triangular bracing structure that provides lateral stability and resists wobbling forces in the previously undefended diagonal direction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If square tube enclosures are used to constrain lumber, then the structural rigidity is improved, but the lumber wobbles inside due to size variations and shrinkage

Engineering Contradiction:

Improvestructural rigidityVSAvoidlumber stability

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

Instead of attempting to constrain the lumber uniformly along its entire length, the invention provides localized bearing surfaces through perpendicular flanges at critical connection points. These flanges create tight local contact zones that prevent movement where forces are applied, while allowing the lumber to maintain its natural dimensions elsewhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The perpendicular flanges are positioned to make initial contact with the lumber before loading occurs, establishing a predetermined tight fit at the connection points. This preliminary positioning ensures that the lumber is constrained in the correct orientation before any wobble or movement can occur under load.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the bracket design is simplified for ease of manufacture, then the manufacturing cost is reduced, but the ability to control lateral forces and wobble is compromised

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidwobble control

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention specifies that the diagonal brace portion extends at approximately 45 degrees from the main body, creating optimal triangular bracing geometry. This parameter choice provides maximum lateral stability while maintaining manufacturing simplicity, as 45-degree angles are easy to fabricate and provide the most efficient force distribution.

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If existing bracket designs are used, then the assembly process is simple, but the lateral forces cause substantial wobble in the A-frame structure

Engineering Contradiction:

Improveassembly simplicityVSAvoidstructural stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The invention combines multiple functions into a single integrated bracket component: the main body provides the primary connection interface, the diagonal brace portion provides lateral stability, and the perpendicular flanges provide bearing surfaces. This merging eliminates the need for separate diagonal brace pieces and multiple fastening systems, maintaining assembly simplicity while providing comprehensive wobble control.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12534902B2Bracket for A-frame structure

Publication Date: 2026.01.27 NASH WILLIAM CARY

AI summary

A bracket and bracket system for constructing an A-frame structure consisting of leg frame members supporting an upper cross beam, such as that used for a children's play set. The bracket includes an elongated top with two side walls, each side wall continuous with the greater part of the top's elongated edges, with each side wall having a second side wall, hereby forming a flange on each side of the bracket for nesting of the leg frame members. The flange is situated in one side of the side wall such that there exists full integral diagonal bracing between the flange and the elongated top of the bracket, with the diagonal bracing being of the same continuous piece of bracket material as at least one of the flanges and as the elongated top of the bracket.