Handheld Circular Saw Arbor Layout for Deeper Cuts

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Solution Overview

Problem

Conventional handheld circular saws suffer from limitations in cutting capabilities, particularly in achieving a sufficient maximum depth-of-cut relative to their blade diameter, which restricts their ability to cut thicker workpieces effectively.

Innovation Solution

The design of handheld circular saws with an arbor rotational axis spaced apart from the motor shaft axis, utilizing a gear system to transfer torque, allows for a higher maximum depth-of-cut ratio, and a base plate configuration that contains most of the saw within its footprint, enhancing cutting versatility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the arbor rotational axis is positioned closer to the base plate to increase maximum depth-of-cut, then the cutting capability is improved, but the motor shaft axis spacing increases device complexity

Engineering Contradiction:
Improvemaximum depth-of-cutVSAvoidarbor rotational axis spacing from motor shaft axis
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent positions the arbor rotational axis in a different spatial dimension relative to the motor shaft axis, specifically spacing the arbor closer to the base plate while maintaining proper motor alignment. This dimensional repositioning allows the maximum depth-of-cut to be increased without requiring changes to the motor's fundamental positioning, thereby resolving the contradiction between improved cutting capability and device complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the handheld circular saw is designed to access confined areas with reduced footprint, then the versatility is improved, but the structural configuration becomes more complex

Engineering Contradiction:
Improveaccess to confined areasVSAvoidbase plate footprint configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by optimizing specific regions of the circular saw design. The base plate footprint is configured to have reduced dimensions in certain areas while maintaining full functionality, allowing the saw to access confined areas. This localized optimization improves versatility without requiring complete redesign of the entire device structure.

Inventive Principle:
Principle #3Local quality

3Length of moving object

If the maximum depth-of-cut ratio is increased to at least 0.35 of blade diameter, then the cutting capability is improved, but the motor diameter and overall device size increase

Engineering Contradiction:
Improvemaximum depth-of-cut ratioVSAvoidmotor diameter
Core Design Contradiction:
Length of moving objectVSVolume of moving object

Solution Approach 1:

The patent changes critical parameters of the circular saw design, specifically setting the maximum depth-of-cut ratio to at least 0.35 of the blade diameter. This parameter optimization allows the saw to cut thicker workpieces while maintaining a compact motor diameter. The arbor rotational axis is positioned to achieve this ratio without proportionally increasing the motor size, resolving the contradiction between cutting capability and device volume.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4171909B1Handheld circular saws with improved cutting capabilities
Publication Date: 2026.04.22 FESTOOL GMBH
  • EP4171909B1 patent drawingFigure 1
  • EP4171909B1 patent drawingFigure 2
  • EP4171909B1 patent drawingFigure 3

AI summary

Handheld circular saws with improved cutting capabilities are disclosed herein. The handheld circular saws include a motor and an arbor, which is configured to operatively attach a circular saw blade to the handheld circular saws. In some examples, the handheld circular saws include the circular saw blade, the circular saw blade has a blade diameter, the handheld circular saw has a maximum depth-of-cut, and a ratio of the maximum depth-of-cut to the blade diameter is at least 0.35 and at most 0.45. In some examples, the handheld circular saw includes a base plate that defines an arbor-facing side. In some such examples, at least 95% of the handheld circular saw is fully contained within a footprint of the handheld circular saw. In some such examples, an entirety of the handheld circular saw may be contained within a base plate width of the base plate.