Plunge Saw Light-Line Cut Indicator for Precise Blind Cuts

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Solution Overview

Problem

Plunge saws face challenges in making precise cuts, especially when cutting within a workpiece's central region or not extending across its entirety, due to difficulty in visually seeing the circular saw blade's leading and trailing edges during operation.

Innovation Solution

Incorporation of a cut indicator that projects a light line onto the workpiece to visually indicate the location of the circular saw blade's edges, enhancing precision by providing additional information to the user.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If plunge saw is used for precision cuts in central region of workpiece, then cutting accuracy is improved, but visibility of blade edges deteriorates

Engineering Contradiction:
Improvecutting accuracyVSAvoidvisibility of blade edges
Core Design Contradiction:
Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

A light line indicator acts as an intermediary visual aid between the blade and the user's eye. The indicator projects a light line onto the workpiece that aligns with the blade position, allowing indirect observation of the blade edges without requiring direct line-of-sight to the actual blade, thus solving the visibility problem while maintaining cutting precision

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanical/physical system of direct visual observation is replaced with an optical projection system. Instead of relying on the user's direct sight of the blade edges, the system uses a light projection mechanism to create visual indicators on the workpiece surface, substituting the observation method while preserving the precision cutting capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If plunge saw operates without cut indicators, then device complexity is reduced, but ease of operation deteriorates

Engineering Contradiction:
Improveease of making precision cutsVSAvoidcomplexity of plunge saw
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The light line indicator serves as an intermediary aid that simplifies the operation by providing visual guidance. It mediates between the complex blade mechanism and the user's control actions, making it easier to operate the plunge saw for precision cuts without requiring the user to directly see the blade edges

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The complex mechanical task of visually tracking and controlling blade position is replaced by an optical information system. The light projection mechanism substitutes for the user's visual tracking effort, reducing the operational complexity while improving ease of making precision cuts

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 improved cut precision and ease in making precise cuts by allowing users to identify the blade edges without direct observation, facilitating better control and accuracy during cutting operations.

Implementation Method 1

a cut indicator (500) configured to project a light line (516) onto the workpiece (98)

Methodology Applied
Scientific EffectLight projection: Light

Data Source

PatentEP4171856B1Plunge saw with cut indicators and method of operating a plunge saw
Publication Date: 2025.07.30 FESTOOL GMBH
  • EP4171856B1 patent drawingFigure 1
  • EP4171856B1 patent drawingFigure 2
  • EP4171856B1 patent drawingFigure 3

AI summary

Plunge saws (10) with cut indicators (500) and methods of operating plunge saws (10) are disclosed herein. The plunge saws (10) include a motor (90) and an arbor (100), which is configured to operatively attach a circular saw blade (200) to the plunge saw (10) and to receive a torque from the motor (90). The plunge saws (10) also include a base plate (304) and a base plate pivot (316). The plunge saws (10) further include a plunge mechanism (380), which is configured to be selectively actuated, by a user of the plunge saw (10) and during operative use of the plunge saw (10) to cut a workpiece (98), to transition (532) the plunge saw (10) from a retracted orientation (54) to a plunged orientation (52) and to plunge the circular saw blade (200) into the workpiece (98). The plunge saws (10) also include a cut indictor, which is configured to project a light line (516) onto the workpiece (98) to visually indicate, on the workpiece (98), a location (504) of an edge of the circular saw blade (200).