Bearingless Router Bit Flared Edge Reduces Tear-Out

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Solution Overview

Problem

Existing router bits cause 'tear-out' when cutting against the wood grain or on non-uniform workpieces due to improper alignment and varying thickness, leading to inconsistent cut depths and undesirable surface finishes.

Innovation Solution

A bearingless router bit with inwardly projecting radial cutting edges having a curvature of 1.0 mm to 2.5 mm, designed to accommodate cutting directions against the wood grain and non-uniform thicknesses, reducing or eliminating tear-out by providing a cutting tolerance and maintaining a consistent cut height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a router bit with straight cutting edges is used, then the cutting depth can be controlled, but tear-out occurs when cutting against the wood grain or on non-uniform workpieces

Engineering Contradiction:

Improvecut depth consistencyVSAvoidtear-out

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies curvature to the cutting edge by incorporating a flared portion with a radius of curvature between 0.5 inches to 2.0 inches. This curved geometry allows the cutting edge to adapt to variations in workpiece thickness and grain orientation, preventing tear-out while maintaining consistent cut depth control.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Productivity

If the cutting edge is made sharp and straight, then cutting efficiency is improved, but the bit cannot accommodate non-uniform workpiece thickness

Engineering Contradiction:

Improvecutting efficiencyVSAvoidaccommodation of non-uniform thickness

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by creating a flared portion at the cutting edge with specific curvature properties, while the rest of the bit maintains its original geometry. This localized modification allows the cutting edge to adapt to non-uniform workpieces without compromising the overall cutting efficiency or requiring changes to the entire bit structure.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the router bit is designed for precise depth control, then manufacturing precision is improved, but alignment sensitivity increases

Engineering Contradiction:

Improvedepth control precisionVSAvoidalignment sensitivity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The flared portion acts as a cushioning feature that compensates for alignment variations and workpiece irregularities before they can cause tear-out or depth inconsistency. The curvature of the flared portion allows the cutting edge to maintain proper contact with the workpiece surface even when there are minor misalignments or thickness variations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10940606B2Router bit with a flared cutting edge

Publication Date: 2021.03.09 WANG HENRY CHI CHAN

AI summary

A bearingless groove router bit includes at least one cutting element affixed to a head of the router bit and has a first end spaced from an end of connected shank connected to the head and a second end adjacent to the second end of the head. The cutting element includes a cutting edge extending along the cutting element between the first end to the second end of the cutting element. The cutting edge may include a radial side edge that projects radially inwardly relative to a central axis of the router bit and a straight side edge that extends from an end of the radial side edge outwardly relative to the central axis to minimize tear out during cutting of a groove in a work piece.