Chain dimensioning is a fundamental practice in technical drawing and computer-aided design (CAD) used to define the sizes and locations of features in a sequential manner. Based on the provided information, specifically in the context of software like SOLIDWORKS, chain dimensions are a particular type of dimensioning.
Understanding Chain Dimensions
In essence, chain dimensions provide a series of measurements taken sequentially along a single direction or path. Instead of measuring each feature from a common baseline (like in baseline or ordinate dimensioning), each dimension in a chain measures the distance between two adjacent points or features in the sequence.
Based on the reference, chain dimensions in SOLIDWORKS are described as:
- Reference Dimensions: They are primarily for informational purposes.
- Driven by the Geometry: Their values are automatically determined by the actual shape and size of the model.
- Non-Driving: You cannot change their values or use the values to drive the model. This means you can't edit a chain dimension value to resize a feature.
This characteristic makes them different from "driving" dimensions which control the geometry.
How Chain Dimensions Are Created (SOLIDWORKS Example)
Creating chain dimensions follows a specific sequence, as outlined in the reference:
- Define the Start: Your first selection defines the starting edge of the chain.
- Measure Sequentially: Subsequent selections are measured from one selection to the next. This establishes the sequential, point-to-point nature of the dimension chain.
For example, if you have several holes along a line:
- Select the starting edge.
- Select the center of the first hole – this gives the dimension from the start edge to the first hole.
- Select the center of the second hole – this gives the dimension from the first hole to the second hole.
- Select the center of the third hole – this gives the dimension from the second hole to the third hole, and so on.
This results in a series of dimensions, each linking to the previous one in the chain.
Benefits and Use Cases
Chain dimensioning is useful for showing the cumulative distance between features or for defining clearances and spaces between adjacent elements. While they don't control the size of the model in the context of reference dimensions, they clearly communicate the manufacturing or inspection requirement for the distance between consecutive features.
Here are some key points about their use:
- Clearly shows the incremental distance between features.
- Useful for defining hole patterns or feature spacing along an edge.
- Because they are reference dimensions in some CAD systems, they don't risk over-constraining the sketch or model.
However, a potential drawback is that an error in one dimension within the chain can accumulate down the line. If the overall length is critical, baseline or ordinate dimensioning might be preferred for controlling that specific requirement.
In summary, chain dimensioning provides a clear, sequential way to dimension features, serving primarily as a reference to understand the step-by-step distances defined by the model's geometry.
