Part 1 of a two-part series on AutoCAD’s powerful dimensioning utility.
AutoCAD Mechanical (ACM) is one of the flavors of AutoCAD and is included with an AutoCAD subscription. It is purpose built for manufacturing drafting, design and detailing. As an AutoCAD user, you already have access to it. You just need to install it.
AutoCAD Mechanical can do everything that AutoCAD can do. But there are many things that set AutoCAD Mechanical apart from AutoCAD. Like what? How about dimensioning? By using AutoCAD Mechanical, you have access to the very powerful Power Dimensions.
Power Dimensions is a set of tools designed for manufacturing. Even when compared to AutoCAD’s quick dimensions and DIM command, Power Dimensions streamlines the detailing process. They are quick to apply and easy to tweak. They are smart and understand their spatial relationships with each other.
Power Dimension
Find Power Dimension in the Home and Annotate ribbon tabs. Use this all-in-one dimensioning tool to add linear, angular, radial, diameter, baseline and chain dimensions.
Power Dimensions automatically recognizes objects and applies the proper dimension type. The default is to create linear dimensions by selecting two points for the ends of the extension lines. As you move the cursor to place the dimension line, ACM adjusts the type between horizontal, vertical and aligned dimension types.
The dimension changing color shows that the current location matches the proper spacing from existing objects. This feature is called Distance Snap. It uses the distance set in the standard by default, but you can override the value with the placement settings. We will discuss setting the standard later.
Power Dimension intelligently spaces dimensions, avoiding overlaps and ensuring the best readability. Distance Snap is one of the settings that controls this.
After selecting the first dimension’s location, ACM pauses, then presents the Power Dimensioning contextual ribbon. More on this in a bit. With the text and formatting set, you can continue to add dimensions. With the last dimension placed, press Enter.
Note that, by default, you cannot snap to existing dimensions and ACM only prompts for formatting on the first dimension placed during the set.
When placing a dimension such that it overlaps an existing dimension ACM displays the Dimension Overdrawn dialog. Use this to rearrange the dimensions, removing the overlap.
Replace removes the existing dimension replacing it with the newly placed dimension. Use Break up to split the existing dimension into two dimensions, aligning the new dimensions. Select Move Away to rearrange the dimensions into a baseline set.
After starting the feature, press Enter (or right-click) to start object selection mode. Now you can select lines, polylines, arcs, circles and other objects. Select an existing dimension to edit it.
The glyph near the cursor indicates the type of dimension to be created by selecting the current object. With lines (and similar), ACM snaps automatically to the object’s endpoints. With circles, it creates diameters and with arcs, it creates radius dimensions.
Opposed to using the dimension line location to set the dimension type created on a selected line, select the desired type from the right-click menu. Selecting an ellipse behaves like selecting a line.
An Aligned Dimension is one where the dimension line is perpendicular to the selected extension endpoints. With a Rotated Dimension, you specify the angle.
After selecting a circle, use the right-click menu (or command line) to toggle between radius, jogged radius and linear type dimensions.
After selecting an arc, use the right-click menu to switch between diameter, jogged radius, arc length, linear and radius type dimensions.
You can manually choose the dimension type from the right-click menu. This is the only way to create an angular dimension with the Power Dimension command.
The Annotate ribbon tab (Dimension Panel) supplies shortcuts for the specific dimension types. This is still the Power Dimension command, just shortened to select specific objects and/or create a specific dimension type.
What is in the standard?
AutoCAD Mechanical is standards based. To learn more about AutoCAD Mechanical standards, take a look at this article
Being standards-based means that ACM can automate many tasks while keeping things standard. For example, mapping object types that should go on specific layers. This means that when you place things like dimensions, ACM automatically places the objects on the correct layers.
From the Options, AM:Standards tab, you set the active standard. Use the Dimension Settings to set the preferences for power dimensions.
ACM bases the dimension settings on a base AutoCAD dimension style.
Although you can edit styles using AutoCAD’s Dimension Style Editor (DIMSTYLE) it is recommended to use the AMOPTIONS. As ACM creates styles on the fly you may not have access to all the required styles from DIMSTYLE. Plus, it is easier to navigate and edit the proper sub-style from the AMOPTIONS dialog.
Enable Force power dimensions to use this dimension style to prevent overriding the style with the AutoCAD DIMSTYLE command.
The Edit Dimension Style dialog shows a tree indicating the root style and its sub-styles. Each sub-style controls a specific dimension type. Although the sub-styles are derived from the base, you can customize each sub-type independently. If the sub-style is bolded, it means it has been overridden from the base.
Use Reset to remove the overrides and reset the sub-style to the base.
Use the Default representations to set the dimensioning style for chamfers, radii and diameters.
The Dimension Text section is where you can add to and tweak the predefined text templates.
From the Fits and Tolerances section, configure the default fit representations and tolerance methods.
In the Placement options, you will find the Distance Snap settings. You can toggle the feature on/off and set the default offset distance.
Also manage the display of the dimension text editor. The default is for only the first dimension in a sequence, but this can be always or only on demand.
Continued on More Power Dimensioning with AutoCAD Mechanical
