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Parallelism constrains how parallel a face or an axis is to its datums. In ASME Y14.5 it is an orientation tolerance: the surface must lie in a zone that is exactly parallel to the primary datum. It does not locate the feature. Two faces can be parallel and still be the wrong distance apart; that distance is a Direct Dimension. Parallelism is in the Toolbar in Dimensioning Mode.

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Which features it accepts

  • A plane — a face that should run parallel to the datum.
  • A cylinder — a hole or a pin whose axis should run parallel to the datum.
The primary datum can be a plane, a midplane, or an axis. A secondary datum is allowed only when it clocks the zone: a plane feature whose primary is an axis. The secondary is a plane datum, and it is optional. A tertiary datum is not used.

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The tolerance zone

The default zone is the space between two parallel planes, set parallel to the primary datum. The tolerance is the distance between those planes, in millimeters. Diametral zone (⌀) is available for a cylinder whose primary datum is an axis. The zone is then a cylinder around that axis, and the tolerance is a diameter. Held across the datum rather than along it, the zone stays two planes and the diametral toggle is not offered.

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Workflow

1

Select Parallelism

Choose Parallelism from the Toolbar, or right-click a plane or cylinder and choose Add parallelism control….
2

Pick the feature

Click the face or the cylinder to control. Eligible features highlight on hover.
3

Set the tolerance

Enter the tolerance. Turn on Diametral zone (⌀) when the control is a cylinder parallel to an axis datum and the drawing uses a diameter.
4

Select the datums

Pick the primary datum. Add a secondary plane datum only when the panel offers that rank.
5

Place the callout and submit

The callout section opens once a feature is picked. Submit to add the control to the feature set. Drag the leader to place the label.

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Reading the result

The callout reports how far the feature leans out of the parallel zone, and whether that is inside the tolerance. Measured in names the datums. Open freedoms lists motion the datums did not stop. Edit the tolerance afterward; the pass or fail state updates without a new extraction.