Drawing Compass Lever Locking Yoke Arms
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Solution Overview
Problem
Conventional drawing compasses face issues with precise adjustment and locking of arm spacing, leading to deviations during circle drawing, and existing solutions are either imprecise or costly due to complex mechanisms and risk of part loss.
Innovation Solution
A compact drawing compass design with a lever mounted on the axis of rotation, applying force to the yoke to lock the arm positions, eliminating the need for additional interfaces and reducing parts, featuring a reversible lever and friction cheek for secure locking and easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the arms are tightened to prevent spreading during drawing, then the arm spacing is locked, but the point cannot be positioned accurately at the beginning
Solution Approach 1:
The locking mechanism transitions from a static tightened state to a dynamic locked state. The lever can be moved to engage or disengage the locking position, allowing the user to switch between adjustment mode (lever disengaged) and drawing mode (lever engaged), thus resolving the contradiction between positioning accuracy and spacing stability.
2Manufacturing precision
If a lever-based locking mechanism is added to the compass, then the arm spacing is locked precisely, but the number of parts increases and manufacturing cost rises
Solution Approach 1:
The lever is integrated with the existing yoke structure through a common pivot point. The lever combines multiple functions: it acts as a locking element, a positioning indicator, and a force transmission component. This merging approach achieves precise locking without proportionally increasing the number of parts, as the lever utilizes the existing yoke geometry and pivot mechanism.
3Ease of operation
If the retaining screw is completely unscrewed to adjust arm spacing, then the arms can be freely positioned, but the screw may detach and lose all parts
Solution Approach 1:
The lever acts as an intermediary between the user's adjustment action and the retaining screw. When the lever is in the locked position, it maintains engagement with the yoke flange, preventing complete disassembly. The lever mediates the transition between locked and adjusted states without allowing the retaining screw to fully detach, thus preventing part loss while enabling adjustment.
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
The solution provides precise and stable arm spacing retention during drawing, reducing the risk of part loss and manufacturing costs, allowing for consistent circle or arc production with ease.
Implementation Method 1
the lever being designed to move from a rest position in which the rotational movement of the arms is free, to a locking position in which the position of the branches is blocked by applying a force to the flange of the clevis such that the flange of the clevis constrains each joint end of the branches housed in the clevis
Data Source
Figure 1~2
Figure 3~4
Figure 5~7B
AI summary
The invention relates to a drawing compass (1) comprising two arms (2a, 2b) mounted to pivot about an axis of rotation (AA) substantially perpendicular to the plane in which the arms (2a, 2b) extend, a yoke (4) housing a hinge end of each arm (2a, 2b) and comprising at least one wing (4a, 4b) covering the hinge end of each arm (2a, 2b), a retaining member (7) designed to hold the arms (2a, 2b) and the yoke (4) together, and a locking device comprising a lever (5), characterized in that the lever (5) is mounted to rotate about the axis of rotation (AA) of said arms (2a, 2b) and is held together by the retaining member (7) with the arms (2a, 2b) and the yoke (4), the lever (5) being designed to move from a rest position in which the movement rotation of the branches (2a, 2b) is free, to a locking position in which the position of the branches (2a,2b) is blocked by applying a force to the wing (4a, 4b) of the clevis (4) such that the wing (4a, 4b) of the clevis (4) constrains each articulation end of the branches (2a, 2b) housed in the clevis (4).