The designs of many assemblies repeat rigid shapes. Sketch blocks can capture such shapes as a fixed set, and you can place instances of the set. For example, say that you have a 2D sketch that represents a hydraulic cylinder, and there are four hydraulic cylinders in your assembly. If you have a sketch block that represents the hydraulic cylinder, you can place four instances of the block into your assembly layout. The instances are defined in the sketch block, and reflect any changes to the block design.
You create sketch blocks in 2D part sketches, and they comprise only sketch objects. You can preselect geometry to create a block, or select geometry with the Create Block command active. The geometry that comprises the block is pulled into the block definition, and an instance of the block definition replaces it.
Some 2D sketch geometry is unavailable to sketch blocks. When such geometry is selected and Create Block executed, a warning message notifies you of the issue. You can create the block, but it does not include the ineligible geometry.
- Arc/circle/polygon center points
- Arc/circle/spline endpoints
- Individual spline points – the entire spline must be selected
- Projected geometry
- Derived geometry
- Geometry copied in a sheet metal Unfold/Refold operation
- Geometry that an iFeature places
Blocks are created with an Insert Point. This point defaults to the centroid of the block geometry, or you can choose a different point. When a sketch block instance is placed, the Insert Point connects the mouse pointer to the block before placement. You can choose to have the Insert Point visible or hidden.
Blocks are created with names and descriptions. You can define your own names and descriptions, or accept the default values. The block name displays in the browser under the Blocks folder. The name also appears wherever instances reside in the browser, with a colon and the instance number at the end. For example, if you define a block called CYLINDER and place the block in Sketch2, the Sketch2 instance is called CYLINDER:1.
You can rename sketch block definitions and instances. If you rename the block definition, the new name propagates through the instance names. However, a change to an instance name overrides the change in the block definition name.
You can define nested sketch blocks and place flexible instances of these blocks to simulate kinematic subassemblies. In the hydraulic cylinder example, you define a nested sketch block that represents the hydraulic cylinder. In your assembly layout sketch, you place flexible instances of the nested sketch block. These flexible instances retain specified degrees of freedom that allow them to simulate the kinematics of the actual hydraulic cylinders. Use this feature to investigate kinematics of your design.
Like other sketch geometry, you can vary the appearance of your sketch blocks. Use Geometry Properties to create formats for your blocks and better communicate your design. Some things to consider when you apply different custom formats to your geometry:
- When a block definition is created, it retains the custom format.
- You can edit the block definition geometry properties. Right-click the definition in the browser, select Properties, and modify the appropriate settings.
- When you place blocks, the instances are created with the block definition format as the default.
- You can change the geometry properties for each instance. Right-click the instance, select Properties, and modify the appropriate settings.
- Use Formatting Toggle on the Sketch Properties toolbar to change between the default and user formats for the selected sketch.
- In the absence of user formats, the Inventor default settings apply.
You can edit sketch block definitions either in-context or out-of-context. When you edit in-context, you can add other active sketch geometry in the block definition. Regardless of how you edit the sketch block definition, the changes are propagated to all instances of the block.
An in-context edit is where you edit an instance of the sketch block definition while you are in a sketch. All visible geometry in the active sketch is available to add to the block definition. Geometry not currently in the block definition is slightly dimmed compared to the block geometry.
An out-of-context edit is where you edit a sketch block definition in isolation using the block definition browser node. As you are out-of-context relative to any sketches, no additional sketch geometry is available for the edit. You can change the geometry that is in the block definition, or you can create new geometry.
To delete a block instance, but keep the objects that make up the instance, use the Explode command. For non-nested block instances, the Explode command removes the block instance and leaves the constituent 2D geometry. For a nested block instance, the instance is removed, but the constituent blocks and 2D geometry remain in the sketch.