In parametric modeling software like Onshape, an assembly is a collection of multiple individual parts or components brought together to form a complete product or system. In other words, it's a way of combining various parts into one cohesive design, representing how those parts fit and interact with each other in the final product.

The assembly environment allows users to position, align, and constrain individual parts relative to each other. Constraints, such as mating, aligning, or limiting movement, define how the parts are assembled and how they interact with each other within the assembly.

Assemblies in Onshape facilitate collaborative design processes, enabling multiple users to work on different parts simultaneously and see how the components fit together in real-time. Any changes made to individual parts automatically update the assembly, ensuring design consistency and accuracy throughout the project.

Assemblies are particularly valuable in complex projects where multiple parts need to be designed and analyzed as an integrated system, such as in mechanical engineering, product design, architecture, and more. They help streamline the design process, improve communication among team members, and ensure the final product functions as intended.

Step 1

Insert the parts of your assembly into your assembly document. You can have multiple copies of the same part in an assembly and you can add any standard parts that Onshapoe already has modeled for you like nuts and bolts.

Step 2

Assemble your parts into an assembly using mates and relations that allow for any degrees of freedom that your assembly may require.

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Step 3

Create an exploded view for your drawing sheets so it is clear where the parts go together on your assembly.  

Mates & Relations


In Onshape, mates are constraints that define how parts are positioned and connected in an assembly. They ensure that components fit together correctly and maintain their intended relationships, such as alignment, rotation, and motion. Mates allow designers to simulate real-world interactions between parts and create functional assemblies in a virtual environment. By applying mates, designers can easily build complex assemblies, check for interferences, and analyze how parts move and interact with each other. The use of mates simplifies the assembly process, ensures accuracy, and facilitates collaborative design efforts.

The Fastened mate rigidly connects two components, restricting all movement between them. It simulates a fixed joint, ensuring the parts stay firmly attached without any relative motion. This mate is ideal for modeling bolted or welded connections in assemblies.

The Revolute mate allows components to rotate around a common axis, simulating a rotational joint. It restricts linear movement while enabling rotational motion, making it suitable for modeling hinges, wheels, and other rotating parts in assemblies. The revolute mate facilitates dynamic movement and realistic simulation of rotating components within the design.

The Slider mate constrains linear movement between two components along a specified direction. It allows parts to slide or translate relative to each other while preventing other degrees of freedom. The slider mate is ideal for modeling linear motion in assemblies, such as drawer slides or telescopic components. It enables designers to simulate and analyze sliding interactions between parts within the assembly accurately.

The Pin Slot mate allows one part to slide along a specified path (slot) while maintaining rotational freedom around a pin. It is useful for modeling sliding mechanisms and guided motion systems in assemblies.

The Ball mate allows rotation about the X,Y,Z axes with the first selection serving as the rotational movement point and the second as the stationary point. This mate allows for the design of ball and socket mates with full range of motion while still having a fixed point.  

The Parallel mate allows for two entities to rotate parallel to each other and translate freely. This is like the slider mate but with the added degree of freedom of rotation but still have the planes fixed parallel to each other. 


In Onshape, relations in assemblies are constraints or connections between components that define their spatial relationships and interactions. These relations ensure that parts within the assembly maintain specific positions, orientations, or motion relative to each other. They play a crucial role in establishing the behavior and functionality of the assembly. They are all based off of mates that have already been established and add an other degree of movement in a particular way. 

The Gear relation creates a constant ratio of angular rotation between two mates with rotational degrees of freedom

The Rack and Pinion relation ties a mate with rotational freedom to a mate with linear freedom.

The Screw relation creates a constant ratio of angular rotation between two mates with rotational degrees of freedom. 

The Linear relation creates a constant ratio of motion between two mates with linear degrees of freedom. 

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