{"id":48030,"date":"2025-03-19T00:19:57","date_gmt":"2025-03-18T23:19:57","guid":{"rendered":"https:\/\/ohmycad.com\/3-external-references\/"},"modified":"2025-03-19T00:19:57","modified_gmt":"2025-03-18T23:19:57","slug":"3-external-references","status":"publish","type":"post","link":"https:\/\/ohmycad.com\/en\/3-external-references\/","title":{"rendered":"3. External references"},"content":{"rendered":"

Introduction<\/h3>\n

First of all, let’s agree on the definition of an external reference.<\/p>\n

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Definition: external references are created when a part is built directly into an assembly<\/strong>. Using the existing geometry of another part to help create a new part generates an external reference. So, if the referenced element changes, so does the reference that depends on it<\/strong>. <\/p>\n<\/div>\n

Using external references is a useful practice when the design is likely to undergo major changes. This applies in particular to preliminary projects<\/strong>.  <\/p>\n

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Please note: at a later design stage (final design, production), external references must be removed or broken<\/strong>.<\/p>\n<\/div>\n

I – A practice… not so practical!<\/h3>\n

While the use of external references may seem straightforward, it tends to give rise to a whole host of complications<\/strong> that we could do without! <\/p>\n

1. Forget about manufacturing<\/h4>\n

As mentioned in the introduction, the geometry of external references depends on the geometry of other parts. So there are no dimensions<\/strong> to speak of, no tolerances or anything else… in other words, it would be complicated to start manufacturing such parts! <\/p>\n

2. Long calculation times<\/h4>\n

Each modification made to the original part will result in the updating of the external references that depend on it. If the assembly concerned is quite large, this can lead to significant calculation times. <\/p>\n

The risk of long loading times<\/strong> when rebuilding, opening or saving parts is increased by the presence of external references. <\/p>\n

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Warning: in addition to wasting time, you may even crash SOLIDWORKS, and lose some of your work.<\/p>\n<\/div>\n

3. Lost or corrupted references<\/h4>\n

Modifying files can also cause problems: moving, renaming or deleting a file<\/strong> can lead to lost external references.<\/p>\n

\"repair-references-solidworks-assemblies\"To illustrate, let’s imagine that we create part 1 in assembly A and wish to use it in assembly B. Part 1 depends on Assembly A, which is not present in Assembly B. This creates an unrelated external reference<\/strong> in assembly B, resulting in a loss of reference<\/strong>.<\/p>\n

As a result, the software will <\/strong>“running around in a vacuum” trying to find the missing references. That’s a lot of computing time for nothing<\/strong>! <\/p>\n

Once again, you’ll waste a lot of time<\/strong> and risk crashing everything.<\/p>\n

4. The vicious circle<\/h4>\n

When you start working with external references, it’s easy to have a lot of them, and above all, to make them all depend on each other. This can lead to cyclical references.<\/strong> SOLIDWORKS may then display error messages or crash. <\/p>\n

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Please note: the more external references there are, the greater the potential for problems.<\/p>\n<\/div>\n

5. Time bomb<\/h4>\n

At the start of the project, external references are fewer, links are not lost – everything works.<\/p>\n

After a few weeks or months, it may not be so well managed: references lost, broken, cyclical… Your assembly is very slow, there’s a problem.<\/strong><\/p>\n

Except that you’re nearing the end of the project, you’re in a hurry, and you need to find the source of this problem. But you’ve got external references everywhere: sketches, functions… It’s almost impossible<\/strong> to delete them all. <\/p>\n

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In CAD, design intent is very important<\/strong>. The work you do in the early days can avoid problems that will only become apparent months later. <\/p>\n<\/div>\n

In short, using external references has a snowball effect on design problems<\/strong>. <\/p>\n

\"TFdF\"<\/p>\n

II – Adopt the right reflexes<\/h3>\n

The use of external references must be a well-considered design intention<\/strong>.<\/p>\n

It’s highly recommended to work without it, to ensure a robust design. However, if the context requires you to work with it, it’s best to learn how to do it properly. <\/p>\n

1. Working without external references<\/h4>\n

Working without dependence on external references is advantageous, as it allows more autonomous design, minimizing the risk of<\/strong> complications associated with file modification. There is also an option to prevent the use of these references<\/strong>, offering an effective means of preventing their use by designers. <\/p>\n

On SOLIDWORKS, simply go to Options, and uncheck the box authorizing the creation of external references.<\/p>\n

\"6-4\"<\/p>\n

2. Working with external references<\/h4>\n

2.1. Keep an eye on external references<\/h4>\n

External references are like children: you have to keep an eye on them<\/strong>! You always need to know where they are and what they depend on. In this way, you can avoid multiple links and other annoyances encountered in the previous section. <\/p>\n

External references can be viewed in the design tree<\/strong>; a small arrow stuck to the name of an element indicates that it is an external reference. These arrows give an indication of the “state”<\/strong>: <\/p>\n

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