Add Fits and Tolerances to Dimensions

The Power Dimensioning Ribbon Contextual Tab provides the Fit/Tolerance Panel to let you add a fit or tolerance to a dimension.

You first select, if the dimension is to contain a fit or tolerance, by latching down the corresponding button in the Fit/Tolerance panel. You then continue to specify the fit representation or tolerance method, depending on your selection.

You can also change the default fit and the tolerance representations to the most frequently used ones. You hence need not change the representation every time you place a dimension.

You can add fits or tolerances to the dimension and choose the representation from a list. You can also control the precision of fits and tolerances, independently of the precision of the dimension value. The drafting standard controls text sizes for the deviation automatically, eliminating the need for additional dimension styles.

Fits

The Representation drop-down contains a list of thumbnails that show various fit representations. Once you select the desired fit representation, you specify the fit notation and number in the Fit dialog box. This dialog box enables you to compare shaft and hole fits and choose an appropriate notation. You can select from the following:

  • Force and shrink fits (FN).
  • Clearance and location fits (LC).
  • Interference locational fits (LN).
  • Transition locational fits (LT).
  • Running and sliding fits (RC).

Once you select the fit notation, AutoCAD Mechanical, calculates deviations based on the Engineer’s Handbook. AutoCAD Mechanical displays these values as part of the dimension text, depending on the fit representation you select.

The AMFITSLIST command generates a fits list from the dimensions you have placed in the drawing area. In model space, if you place the fits list within a drawing border (created using the AMTITLE command), it reports only the fits within that drawing border. If you place the fits list outside a drawing border, it reports all fits in the drawing. If you add, remove, or modify fits, AutoCAD Mechanical attempts to update the fits lists. If required, you can opt not to update at this time and use the Update option of the AMFITSLIST command later.

Tolerances

The Tolerance drop-down contains a list of thumbnails that show various tolerance methods. Once you select the desired tolerance method, specify the deviations.

If the list of available fit representations and tolerance methods does not contain the format you require, you can create your own and add them to the list. See Change the Representation of Fits and Tolerances for more information.

Procedures
To add a tolerance to dimensions

  1. In the drawing area, double-click the dimension you want to edit. The Power Dimensioning Ribbon Contextual Tab displays.
  2. Click .
  3. Click Power Dimensioning tab Fit/Tolerance panel Method drop-down.
  4. Select the desired tolerance method.
  5. Enter a value for the upper and lower deviations.
  6. Click Power Dimensioning tab Close panel Close Editor.
To add fits to dimensions

  1. In the drawing area, click the dimension you want to edit. The Power Dimensioning Ribbon Contextual Tab displays.
  2. Click Power Dimensioning tab Fit/Tolerance panel Fit.
  3. To change the fit representation, click Power Dimensioning tab Fit/Tolerance panel Representation drop-down.
  4. Click the icon corresponding to the desired representation.
  5. Click the Power Dimensioning tab Fit/Tolerance panel Symbol drop-down Fits Dialog box.
    NoteFor some representations you must select symbols for the hole and shaft separately. In this case the Power Dimensioning tab Fit/Tolerance panel does not contain a Symbol drop-down. Instead it will contain 2 separate drop-down lists for the shaft and hole. In this case you must repeat step 6 for both, drop-down lists.
  6. Select the required symbol and click OK.
  7. Press ESC.
To change the precision of a fit or tolerance
  1. In the drawing area, double-click the dimension you want to edit. The Power Dimensioning Ribbon Contextual Tab displays.
  2. To change the precision of the tolerance of primary units, specify the number of digits to round off to, in the box adjacent to Power Dimensioning tab Fit/Tolerance slideout panel Primary Primary.
  3. To change the precision of the tolerance of alternate units, specify the number of digits to round off to in the box adjacent to Power Dimensioning tab Fit/Tolerance slideout panel Alternate.
To create a fits list
  1. Click Annotate tab Table panel Fits List. At the Command prompt, enter AMFITSLIST.
  2. Press ENTER to accept the default option. This action creates a fits list.
  3. In the drawing area, specify an insertion point for the fits list.
To set the default fit representation
  1. At the Command prompt, enter AMOPTIONS.
  2. In the Options dialog box, click the AM:Standards tab.
  3. In the Standard Elements list, double-click Dimension. The Dimension Settings dialog box appears.
  4. Click Fits. The Fit Representations dialog box appears.
  5. From the drop-down list, select the default representation for fits.
  6. Click OK until all dialog boxes close.
To set the default tolerance method
  1. At the Command prompt, enter AMOPTIONS.
  2. In the Options dialog box, click the AM:Standards tab.
  3. In the Standard Elements list, double-click Dimension. The Dimension Settings dialog box appears.
  4. Click Tolerance. The Tolerance Method dialog box appears.
  5. From the drop-down list, select the default method for tolerances.
  6. Click OK until all dialog boxes close.
Commands
AMFITSLIST

Generates a fits list from the dimensions in the drawing area and places it at a location of your choice.

 Ribbon: Annotate tab Table panel Fits List. Not available on the ribbon in the current workspace.
 Toolbar: Dimension
 Menu: Annotate Fits ListDoes not exist in the menu in the current workspace.
 Command entry: amfitslist

If you place a fits list within a drawing border created with the AMTITLE command, it shows only the fits within that drawing border.

COMMAND LINE OPTIONS

Fits lists [Update all/Order/New] <New>: Press ENTER to create a fits list, enter O to order the fits lists by size, or enter U to update existing fits lists in the drawing.

Update

Select this option when you have changed or added fits.

NoteThe Dimension Settings dialog box, accessed through the AM:Standards tab of the Options dialog box, contains settings to update fits lists automatically.

Order

You can order fits list by values or fits.

New

Inserts a new fits list.

Insertion point: Select a point to insert the fits list.

AMDIMLAYOUTOSNAP System Variable

Controls object snap to virtual snap points between model space and paper space entities, while annotating viewport geometry in a layout.

This system variable applies to the follwing annotation commands

  • AMPOWERDIM and all its variants.
  • AMAUTODIM
  • AMDIMINSERT
  • AMHOLECHART
Type

Integer

Initial Value

1

Possible Values

0 – Turns off virtual snap points between model space objects and paper space objects.

0 – Turns on virtual snap points between model space objects and paper space objects.

Power Dimensioning dialog box

Use the Power Dimensioning dialog box to set dimension text, specify accuracy for dimension values, or add tolerances and fits to dimensions. This dialog box appears when you apply Power Edit to dimensions.

If the Power Dimensioning dialog box is not visible, enter CMDDIA on the command line and enter 1 to turn on the dialog box display.

Expands the dialog box so you can specify fit values.

This button is not visible if the dimension is based on the ANSI standard.

Expands the dialog box so you can specify fit values.

This button is visible only if the dimension is based on the ANSI standard.

 

Fit

   

Symbol

Specifies the fit symbol. Click the button to display the Fits dialog box, enabling you to pick the symbol and the deviation from a list. These options are visible only if you expand the dialog box using the or buttons.

   

Hole

Specifies the symbol to use for the hole tolerance, in a stacked fit representation. Click the button to display the Fits dialog box, enabling you to pick the symbol and the deviation from a list.

This option is visible only for stacked fit representations.

   

Shaft

Specifies the symbol to use for the shaft tolerance, in a stacked fit representation. Click the button to display the Fits dialog box, enabling you to pick the symbol and the deviation from a list.

This option is visible only for stacked fit representations.

 

Precision

   

Primary

Specifies the number of decimals for the primary unit. This option is visible only if you expand the dialog box using the or buttons.

   

Alternate

Specifies the number of decimals for the alternate unit. This option is visible only if you expand the dialog box using the or buttons. It is available only if you select Alternate units.

Expands the dialog box so you can specify settings for the tolerance.

 

Deviation

Specifies the maximum and minimum tolerance value for the dimension.

   

Upper

Specifies the difference between the nominal dimension value and the maximum limit. This option is visible only if you expand the dialog box using the button.

   

Lower

Specifies the difference between the nominal dimension value and the minimum limit. This option is visible only if you expand the dialog box using the button.

 

Precision

Specifies the number of decimals for the tolerance value.

   

Primary

Specifies the number of decimals for the primary unit. This option is visible only if you expand the dialog box using the button.

   

Alternate

Specifies the number of decimals for the alternate unit. This option is visible only if you expand the dialog box using the button. It is available only if you select Alternate units.

 

Preview

Displays a preview of the fit or tolerance. Click the preview to change the tolerance or fit representation.

General tab

 

Dimension Symbol

Displays a graphical representation of the current dimension text. Click the button to the right of this box to select dimension text and special characters from predefined templates.

   

Displays dimension values in both inches and millimeters. The alternate units appear between square brackets.

   

Underlines the dimension value to indicate that the dimension is not to scale.

   

Draws a box around the dimension value to indicate that it is a theoretically exact dimension.

   

Draws a box around the dimension value to indicate that it is an inspection dimension.

   

Draws parenthesis around the dimension value to indicate that it is a reference dimension.

 

Text

   

Specifies that the dimension value must appear as part of the dimension text.

   

Displays a palette of special characters to add to dimension text.

 

Value

   

Exact Distance

Displays the actual value for the current dimension.

   

Precision

Specifies the number of decimals for the dimension value.

 

Properties

   

Apply to

Applies the properties of the current dimension to other dimensions. The dialog box hides enabling you to select the dimensions to apply the properties to. Thereafter the Select Properties to Copy dialog box appears enabling you to specify which properties.

   

Copy from

Imports the properties from another existing dimension. The dialog box hides enabling you to select the dimensions to copy the properties from. Thereafter the Select Properties to Copy dialog box appears enabling you to specify which properties.

Inspection tab

 

Shape

Controls the shape of the frame drawn around the label, dimension value, and inspection rate of the inspection dimension.

   

Round

Creates a frame with semi-circles on the ends. Vertical lines separate fields within the frame.

   

Angular

Creates a frame with lines that form a 90-degree angle on the ends. Vertical lines separate fields within the frame.

   

None

Draws no frame around the values. Does not separate fields with vertical lines

   

Graphic showing extension lines and arrowheads

Controls the dimension text, arrowheads, extension lines, and force line inside options. Move the pointer over the graphic to display tooltips. Click arrowheads to display a pallet of options.

 

Label/Inspection Rate

Controls the settings for the inspection dimension. Optionally shows a label and rate as part of the inspection dimension. You can control the label and rate fields individually, so it is not necessary to display both.

   

Label

Toggles the display of the label field on/off in the inspection dimension.

   

Label Value

Enables you to enter the label used to identify individual inspection dimensions. The label appears in the leftmost section of the inspection dimension when you select the Label check box.

   

Inspection Rate

Toggles the display of the rate field on/off in the inspection dimension.

   

Inspection Rate Value

Enables you to enter the rate used to indicate the frequency with which the part is inspected. The value is expressed as a percentage, and the valid range is 0 - 100. The inspection rate appears in the rightmost section of the inspection dimension when you select the Inspection Rate check box.

Geometry tab

 

Text offset from dimension line

Sets the size of the gap between the text and the dimension line.

 

Center mark size

Sets the size of the center mark. This option is visible only if you are setting options for a radius or diameter dimension. This option is not available by default. To make this option available, click the Center mark in the graphic showing the elements of a circle.

 

Graphic showing extension lines and arrowheads

Controls the dimension text, arrowheads, extension lines, and force line inside options. Click the appropriate place in the graphic to customize that element. For example, click an arrowhead to display a palette of options. A tooltip shows the name of the element that can be controlled as you move the pointer over the elements of the graphic.

Units tab

 

Primary

Sets options for primary units

   

Units

Sets a unit type for dimensioning.

   

Linear Scale

Sets a scale factor that multiplies the dimension value.

   

Round Off

Sets a value for rounding off all dimensioning distances.

 

Alternate

Sets options for alternate units. These options are available only if you select Alternate units in the General tab.

   

Precision

Sets the number of decimal places for alternate units

Tolerance Method dialog box

Use the Select Tolerance Type dialog box to select a tolerance representation.

Choose a tolerance method

Graphically shows the current tolerance method. Click the drop-down arrow next to the image to display a list of tolerance methods and click the method to use.

   

Fit Representation dialog box

Use this dialog box to select a fit representation for the selected dimension.

Choose a fit representation

Graphically shows the current fit representation. Click the drop-down arrow next to the image to display a list of representations and click the representation to use.

   

Fits dialog box

Hole tab

Specifies a fit for the current dimension value of the hole. Information about the fit appears in this tab.

Shaft tab

Specifies a fit for the current dimension value of the shaft. Information about the fit appears in this tab.

Graphical representation

Displays a graphical representation of the fit’s deviation from the nominal size.

Mating

Expands the Fits dialog box to display both the Hole and Shaft tabs. A graphical combination of both fits appears. Besides the tab and shaft information section, a mating information section appears.

Tolerance Methods dialog box

Use this dialog box to set the defaults for tolerance methods.

Choose the default method for tolerances

Graphically shows the default tolerance representation. Click the drop-down arrow next to the image to display a list of representations and click the representation to set as default.

Customize tolerance methods

 

System Editor

Displays the System Editor, which enables you to modify the Windows registry settings that define the existing set of tolerance representations as well as create new ones.

Fit Representations dialog box

Use this dialog box to set the defaults for fits.

Choose the default representation for fits

Graphically shows the default fit representation. Click the drop-down arrow next to the image to display a list of representations and click the representation to set as default.

Customize fit representations

 

System Editor

Displays the System Editor, which enables you to modify the Windows registry settings that define the existing set of fit representations as well as create new ones.