CAD Etiquette/Tips for Large Assemblies

Owned by Austin Tailon Huang
Last updated: Apr 09, 2021 by Ethan Cronier
7 min read

The purpose of this guide is to describe some good practices to keep in mind when working on assembly files for the rover. These tips will help you to cleanly organize your CAD so it's easy for other members to follow. Also, it will help you reduce the number of files used on start-up and reduce the number of mates saved within the assembly (so start-up times should run a bit smoother). If you have any questions, you can message the authors of this guide Austin Tailon Huang Ethan Cronier (smile).


FeatureManager Folders

  • Super obvious, but you should always try to organize parts within your assembly into various labelled folders. How these folders are set-up and divided in your assembly is really up to you and depends on what's going on in your assembly. However, one folder that is always good to have is a "Fasteners" folder, which will hold any individual fastener files used in your assembly.
    • Using the e-box as an example, all parts have been organized based on what panel they are located on. Other external features like the interior components, actual connector CAD files, and fan components have also been placed in folders. The "Fasteners" folder is also present in this tree (smile)
    • Try not to go over-board. sometimes less is more.


Mating Tips

  • When starting your assembly, make sure your "base part" has it's part origin mated to the assembly origin. This will hopefully ensure that the assembly planes stay in the correct position. 
  • Try to mate faces/planes together rather than edges/points when possible. Face/plane mates are typically more stable than edge/point mates, as if you make any edits to a feature edge/point mates can easily get displaced and completely break the mate in assembly. 
  • Always make sure that you select "Delete child features" when deleting components in your assembly! This will make sure that all mates associated with the deleted part are ALSO deleted. If you don't have this box selected, the mates will remain in the FeatureManager tree as a suppressed mate, which can be quite confusing when reviewing and fixing mates in an assembly in the future.


  • Use the profile center mate when possible! The profile center mate is a very powerful mate that can be used to replace a coincident + concentric mating pair.
  • When using concentric or profile center mates, lock the rotation of the components unless rotation absolutely 100% needs to be flexible! Pretty much all fasteners should be locked concentrically.
  • Lets say you have 3 parts mated together, where all 3 depend on each other. Mate in such a way to reduce the dependencies. for example mate B to A and C to A instead of C to B and B to A, if that makes sense. In other words mate all parts to a master instead of chaining mates.

Component Patterning

  • Component patterning is a very powerful tool to simplify your assemblies and clean up your FeatureManager tree. There are various types of component patterns, so generally you can always find a way to pattern a component in your assembly. 
  • The only main drawback of component patterning is that they can be somewhat unreliable when working with flexible assemblies. Make sure that all your patterns are performing as intended after you implement them by testing out the assembly and making sure that the patterns don't break. 

  • When using any pattern type, make sure you properly rename (select then F2) the pattern on the FeatureManager tree to reflect what the pattern achieves. See the example of the patterns in the e-box feature tree as reference:
  • Linear and Circular Component Patterns
    • Linear and circular component patterns are very straight forward methods to pattern components. I'm not going to spend too much time explaining these two, as they work exactly as their name suggests - choose a host component, specify either linear or angular spacing, and select pattern quantity. 
    • The only thing of note for these types of patterns is that you can make modifications if there is asymmetry in your patterns by selecting the "Skipped instances or Modified instances" tab. Both of these instance modifications do exactly as their name suggest, and when you click this option pink nodes show up on the pattern preview so you can select what to skip and modify. 
    • As an example, in the e-box linear component patterns were used to create various copies of connector mounts on the front panel. 


  • Sketch Driven Patterns
    • Sketch driven patterns offer a great way to create multiple instances of a component asymmetrically on a single plane. To use a sketch driven pattern, you need to create a sketch that includes points/nodes at all instances where you want to copy components. Generally, the component origin is the best option for choosing the component reference point, but play with the options to make sure the pattern comes out correctly. 
    • Sketch driven patterns also provide the option to skip instances if need be. 
    • If you are using a floating sketch in the assembly to derive your sketch driven pattern, make sure you name the sketch properly and fully define it within the context of the assembly!
    • As an example, see how a sketch driven pattern was utilized in the e-box. A floating sketch was fully defined on the front panel of the box to select all locations where a 6-32 bolt and nut would be required. The bolt and nut where inserted into the assembly and mated at the host location (circled in red) and all other copies of the bolt and nut were generated using the nodes for the sketch driven pattern


  • Pattern Driven Patterns
    • Pattern driven patterns are also a great tool to pattern any component that are mated in multiple hole features. The pattern driven pattern derives it's patterning logic by using hole wizard features on a specific part.
    • To use this pattern type, first mate all host components to a one of the holes. In this example, I've mated a PEM nut to one of holes in the bottom panel of the e-box.
    • Next, select pattern driven pattern and select the components you would like to have patterned. In the e-box example, this will be the PEM nut that I mated in the previous step.
    • Then, select the hole feature that will act as the seed position for the copied parts. In the e-box example, I've selected the #10 clearance hole feature that is included in the e-box frame (outlined in red).
    • After selecting the hole position, you will want to ensure that the seed position is the same node that currently has the mated parts. You can change the seed position by clicking "Select Seed Position" and selecting the node where your parts are mated
    • Then, you can select any instances to skip and your pattern driven pattern is good to go!
    • This pattern type works particularly well with fasteners, however Smart Fasteners is also a great way to pattern your hardware (smile).
  • Mirror Components
    • Mirror components is a very straight forward patterning feature. All it does is mirror selected components across a selected plane. Its great!
    • This pattern style is particularly useful if you're assembly planes are properly aligned with the origin of your assembly.

  • Make sure that you never mate new components to patterned patterned components. Components should always be mated to other inserted components!


Miscellaneous Tips

  • The section view tool allows you to easily view cross sections of your assemblies! You can move the section plane by adjusting the offset, or you can select actual part faces.


  • If the assembly is lagging out your computer, you can reduce the image quality of the assembly by clicking Tools → Options → Document Properties → Image Quality. You can also switch to shaded view with no object lines to help things run smoother.