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Example Model:C:\Users\Public\Documents\DCS\3DCS_All Platforms_8_0_0_1\3DCS CAD & Example Models\Reference Models\Tolerances\Arc Tolerance
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Input:
Distribution
Required
Magnitude
All parameters required
Name
Required
Direction
Required
Point List
Required
Angular Options
Required
Description
Optional
Methodology:
This tolerance deviates the point in the path of an arc. The plane on which the point deviates, is created by the vector direction and a center point.
STEP 1
A Center point and vector Direction define the plane in which the point(s) deviates. The center point is also the center of the arc radius. Only one plane and center can be defined per tolerance.
STEP 2
Rand#1 controls the distance from the center point to the toleranced point. The radius of the arc is the multiple of the distance from the center point to the toleranced point and the Offset. A Distribution of Constant and an Offset of 1 will deviate the tolerance in a arc at its current distance from the center point. The Range controls the variation of the arc radius. A Range of 1 (+/-0.5) will shrink the radius by half and enlarge the radius by half. A Range greater than 2 will allow the radius to become negative and the toleranced point to deviate on the other side of the center point. If the distance between the center point and the toleranced point varies before this tolerance is activated the varied distance will be used to calculate the Range and Offset of the arc radius.
STEP 3
Rand#2 controls the length and angular position of the Arc Tolerance path. The toleranced point will vary in an arc within the angular Range defined. If this Range is 360 deg, the arc tolerance path will be a complete circle. The Offset will define the location of the middle of the arc. The arc tolerance path will be offset from the toleranced point's current position according to the right hand rule.
STEP 2
The point deviated about the center point by the magnitude is rotated from the start angle to a random angle range. The random angle range is determined by the angular range (plus & minus), distribution, sigma, truncation and scale values. The angle is perpendicular to the direction vector.
Parameters specific to Arc Tolerance
Most parameters that are to be defined under Arc Tolerance are specified under common parameters. Center, however, is specific to this tolerance. Furthermore, Mode and Direction have specific denotations in this tolerance.
Center:
The Center button defines the center of the arc to which the tolerance is applied. Clicking on this button brings up the Graph window and lets you click on the point. Once the point is defined the point name along with its part is displayed.
Mode:
The Mode option lets you specify different combinations of magnitude and direction for greater flexibility. The Mode option has two choices: Individual Mode and Group Mode.
Individual Mode:
When Individual Mode is specified, each point in the list that is associated with the tolerance varies:
• With different magnitudes in the specified range.
• In the same plane.
Group Mode:
When Group Mode is specified, each point in the list that is associated with the tolerance varies:
• With the same magnitudes in the specified range.
• In the same plane.
Direction:
Specify the Vector Direction for the tolerance.
• Type In
• Two Pt
• Normal
• AssocDir
• PickPtDir
Type In Method
Varies a point in the path of an arc on a plane normal to the vector specified.
Two Pt Method
Varies a point in a direction normal to the vector of the line segment chosen. Select a line segment (2 points) normal to the plane of the arc path.
Normal Direction Method
Varies a point in a plane parallel to the three points chosen. Select 3 points to specify a plane. The point will vary in a plane located at the center point parallel to this plane.