What is an adjustable assembly?

An adjustable assembly is a construct within Solid Edge that allows you to do one of the following:

1)    Allow movement within a subassembly while working in a higher-level assembly.

2)    Allow you to place identical subassemblies in different positions within the higher-level assembly.

Over the years I have supported numerous customers who have had issues with adjustable assemblies. Although they are often easy to create, editing and manipulating them can be confusing. In this blog article, I will point out a few tips for working with them, which I hope will make it easier to work with your own adjustable assemblies.

How to create adjustable parts and assemblies

Before I start with some tips, I first want to address those of you who may not know how to create adjustable parts and assemblies. Solid Edge allows you to create adjustable parts. A typical example of an adjustable part is a spring. If you create a spring as an adjustable part, you can place it into an assembly at different compressed lengths. If you place 3 identical adjustable springs in an assembly, all at different compressed lengths, the BOM will see them as 3 identical springs. This is a big reason for using adjustable parts. Of course, the next logical step was to use these parts in assemblies to create adjustable assemblies. For those of you who want to learn about adjustable parts and assemblies, Solid Edge has an online self-paced course at this link:

https://docs.plm.automation.siemens.com/data_services/resources/se/2020/se_help/training/en_US/xid1012451/index.html?goto=adjust1a.html

Important tips for working with adjustable assemblies

First and foremost, read the entire documentation on adjustable assemblies. Sadly, most users read the information on how to create the adjustable assembly, but not how to edit it. When it comes to editing your adjustable assemblies, you must be aware of all the rules and understand how it was created. I have seen examples where a user was trying to drive motion in a top-level assembly from within an adjustable assembly. It just doesn’t work that way. Once I explained it to him, and understood what he needed, we were able to create a top-level variable to achieve his needs. The following video gives an example of this using one of the Solid Edge assemblies. Although this is not the exact model the user was having issues with, I chose to duplicate a similar issue on one of our assemblies, so as not to expose his company’s CAD data.

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In this video, I showed some of the tips that you should be aware of before attempting to edit adjustable assemblies. To be clear let me list them now in case you want to keep these for future reference. Note, these points are derived from or taken directly from the online course and the Solid Edge Help documents.

- Make sure you understand how you want the assembly to adjust and model it with that adjustment in mind.

 - To use the Adjustable Assembly functionality, the subassembly can be left under-constrained in the range of motion in which you want to adjust. This allows you to apply the relationship(s) that you want to adjust in the higher-level assembly, not in the subassembly.

Note: Only subassemblies that contain parts that are not fully positioned can be marked as adjustable.

-  When a subassembly is set to adjustable, all assembly relationships existing within the subassembly are solved at the level of the active assembly. In other words, the relationships in the subassembly are promoted to the higher-level assembly for solve purposes.

- The relationships used to position the parts within the subassembly can be viewed in the bottom pane of PathFinder when you select a part in the subassembly. These relationships are read-only, and the text label is gray to indicate that the relationship cannot be edited. Displaying the read-only relationships makes it easier to evaluate the existing relationships and apply the remaining relationships.

- If you specify that a subassembly is flexible, add positioning relationships,and then specify that the subassembly is rigid, conflicting relationships can occur. You can delete or suppress relationships to correct this situation.

 - Relationships in adjustable assemblies can also be overridden. This promotes the relationship up to the current assembly and is useful for making assemblies that are fully constrained adjust without having to provide and under constrained part in the subassembly. (For a more detailed explanation on how this works view the “Override relationships in constrained assemblies” section in the online course and the Solid Edge Help documentation.)

 - If you define an assembly variable in the variable table for a subassembly that controls a part variable, the subassembly variable is promoted to the current assembly. The promoted variable is a linked variable.

- Because an adjustable subassembly is typically used to drive movement in an assembly, you may need to provide for that movement by suppressing or deleting relationships in the related parts and subassemblies. Note: This is a typical mistake that I have seen users make. The subassembly adjusts on its own, but fails to adjust in the top-level assembly, because the user failed to allow for that adjustment by locking down the top-level assembly.

- To get predictable results when creating an Adjustable Assembly do not form relationships between parts and assembly-level coordinate systems,base or reference planes, or sketches. The first part in the assembly should be grounded. All subsequent assembly relationships should be formed between other parts in the assembly or the grounded part, and not to assembly-level coordinate systems, base or reference planes, or sketches.

As I stated already, it is important to read all the documentation pertaining to adjustable assemblies. The points listed above are often ignored, overlooked, or forgotten by users. Which leads to some frustrating, yet avoidable issues. So please take a few moments andreview the documentation, it could save you hours of frustration down the road.Always remember, that if you still have issues, and you are a Designfusion customer, contact us at support@designfusion.com or 1-877-215-1883.If you are not a Designfusion customer, contact you local VAR for assistance.

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