LAST CHECKED:
October 29, 2026
Emil Rindell
Jonas Bryntesson
Henrik Andersson
PUBLISHED:
2020-01-01
Emil Rindell
Jonas Bryntesson
Henrik Andersson
2020-01-01
This post is designed to provide you as a user with better knowledge regarding the handling of external links in ironcad. We cover most contexts where external links are used and affected in various ways.
An externally linked part or subset is a specific 3D file (.ics is the 3D file format used by IRONCAD ) that is also part of another 3D file. It can be likened to a shortcut to a specific 3D file into from another 3D file, which can also be used in several places at the same time. If a 3D model is externally linked out from a main assembly, it is not actually "embedded" in the assembly, but only a link to the external file's 3D model is used. The only thing "embedded" in the main assembly is the information about the path to the other file, so that changes made to the 3D model are reflected in the external file and in all other places where that file might be used. Nevertheless, the 3D model itself is visible and works as usual in the main assembly.
An external link appears in the Scene Browser as a small text icon with a path, just below the part or assembly icon.
IRONCAD does not need to use external links. You can have a 3D scene (i.e. 1 file) with thousands of parts and assemblys in it. The advantage of this is that there are considerably fewer files to keep track of, simply one. The disadvantage of a single file is that it can be very large in file size and slow to work with, something that you may only notice after a long period of work.
By selecting and saving parts and assemblys to external links - via the Save As Part/Assembly function - you don't put the same strain on your computer and the programme. Instead of then opening up x number of parts in a file, a "shortcut" to the external links is opened via a path. Dealing with these simple shortcuts instead of the 3D models directly allows files to be opened and saved more quickly.
You can also link in files that are already completed and perhaps used in other machines or projects—in this case, via the Insert Part/Assembly function.
NOTE! You should ideally avoid using the Import button when linking files in ironcad's *.ics format. When importing, there are no options to link or not link the imported data. Import should instead be used for files in all other CAD formats.
Thus, opening and working with a master file, with a large number of parts and sub-files keeping the parts apart, can be facilitated by using external links, compared to having only a single file. However, there is no need to save all the batches and subsets to their own files. Usually bolts, nuts and other simple details are directly in the file without being externally linked.
You can use external links, but you don't have to. When and why should you use them? There are various reasons and answers to that question. One example is saving out an external link on all parts to be manufactured rather than purchased (which are then imported). As you finish a 3D model, you name it, assign properties such as part number, description, and material, and save it out to its own file.
This also simplifies the subsequent creation of 2D drawings by allowing you to use the standalone part file. The same approach can be used for weldment drawings of sub-assemblies or assembly drawings of sub-assemblies. A helpful tip is to gather all 2D drawings and 3D files in a single folder. This allows you to check (via the Detailed List setting in File Explorer) when the files were last saved and easily verify that the 2D drawing is not older than the depicted 3D scene, which would imply the drawing likely needs to be updated.
Imported files coming from other CAD systems can be imported into a blank 3D scene, saved and then linked into a main assembly. It also saves the effort of then opening and saving the file where it is included.
Right now, you may find that a particular part or assembly should no longer be linked to an external file, perhaps because you want to make a special version of the original. Breaking the link is very simple, right-click on the part and select Unlink (External) and the instance of the part you are now working with will not affect other instances of it in other files.
OBS! If it is a assembly that you break the link on, it may still contain parts or subsets that are externally linked. These are not automatically broken just because the link at the top level is broken. Then you need to check it with e.g. the Find References tool. This is also the case if you link into a assembly and deselect the Insert as link option. All elements of the assembly are still linked externally, even if this option is deselected. If these are to be broken, this is done manually as a step 2 e.g. with the Find References tool.
Once any modifications have been made, you can choose to save this variant out again as a new externally linked file—perhaps with a new name and drawing/part number—using the Save As Part/Assembly function.
When working with external links of parts and assemblys in IRONCAD , it can sometimes be tricky to know how to take copies of parts, without the changes made to the new parts affecting the original files. When saving out a file, you can choose not to link it, by turning off the Link to current scene option. Only a copy of the part will then be saved out, however the same applies as above, if it is a assembly that itself contains externally linked parts. The link on these is not broken automatically, but you have to check and break these manually as a step 2.
There are also other ways to create variants of assemblys with external links. We explain more about this later, in the section Things to consider when using external links.
One way to get a quick overview of the number of external links present in a 3D scene is to launch the Find References... tool via the ironcad menu, File.
This displays a list of all externally linked objects in this 3D scene. You also have the option to break the link for the selected item using the Unlink button at the bottom right. You can choose to display even the objects that are not externally linked, and get a complete tree, by unchecking the option Show only external linked references.
There are several things you need to consider when making copies of or breaking external links. Here we list some of them.
If you open and save a copy (via Save As) of a file that is included as an externally linked part or part, it is important that the file representing the level above is not open when you save the copy. The file "above" will then use the new path to the file.
Close all files and then open only the file you want to save a copy of. Save to the new folder or with the new name. The main assembly will now not use the new file but still open the old one, since it was not itself open and registered it when the file was resaved.
The same applies when re-saving 3D files while their 2D drawing is open at the same time. In that case, the 2D drawing will automatically be re-linked to the new 3D file. If this is not what you want, make sure the 2D drawing is closed before saving the file again.
If you want to create a copy (via Save As) of the entire main assembly (or a sub-assembly) which in turn contains a number of external links, you will have several options to choose from.
OBS! None of the options will break the link to the main assembly, it is just different ways that the links should be handled. If you want to make a variant of an existing model, the first option is recommended, read more below.
Will make copies of all constituent files and place them in the new folder. All names are retained as the originals. This is the recommended option when you want to create a new variant of an existing project, where all parts should be based on an existing model, but changes to individual parts must not affect the original. In short, a way to create a revision or a variant of a machine in a new folder.
Only modified links (changed in terms of shape) will be copied to the new folder, while the unchanged ones will be kept in the original folder.
A Save As dialog will appear for each individual file, suggesting the original folder. You can then give them a new name.
A Save As dialog will appear only for the modified (shape-changed) objects that are externally linked, suggesting they be saved in the original folder. You can then give them a new name.
A Save As dialog will appear for each individual external link, allowing you to choose to place them in any folder with any name.
Only the main assembly will be re-saved (new folder and/or new name), but all external links will be maintained and used from the original folder. The same external files will then be used in two different main assemblys and changes to external links in either of them will be reflected in both.
NOTE! Therefore, no links will be broken with this option!
If you then want to break all links, you must do so manually. This will naturally affect the file size (it will increase) and the time it takes to open and save the file (it will take longer), as all parts remain but are no longer externally linked. There are also options to save links with different names or file paths.
You can either open the Find References... tool (see more under Undoing and breaking an external link?), select all rows there, and click the Unlink button.
You can also use the add-on tool External Link Manager from IronPRO XT. Read more about it under IronPRO XT - External Link Manager.
It is also possible to maintain external links in directories. When a part or assembly that is externally linked is dragged and dropped into a directory, the question is asked whether the link to the external file should be maintained. It is important to remember that the question is only asked when items are dropped into a directory, never out of a directory!
If you answer Yes to the prompt, you will subsequently see in the catalog object's name that it is linked to an external file (Linked to a file). Thus, you will always get a link to the external file when the object is dropped into the 3D scene. To break this permanently, you must either open the catalog object (by right-clicking its icon in the catalog) and break all links within it, or do so afterward by right-clicking the objects dropped in the 3D scene.
If you answer No, it simply becomes a copy that neither affects nor is affected by the external file it was originally linked to. You cannot link an object in a catalog retroactively. Instead, you can drag a new object out of the catalog and answer Yes when the prompt appears.
The add-on program IronCAD Mechanical (ICM) features a special tool in the ICM Tools catalog called External Link Manager for managing external links. It allows you to break, relink, and open external links, among other things.
The tree displayed in the window lists only the files currently externally linked in this 3D scene. The buttons at the top light up depending on what is selected in the list below.
The Unlink Selected Nodes button will only light up if one or more parts/smst are selected. It is used to break the link directly only on the selected objects. After breaking all links, it is important to close the tool and save the scene. This applies regardless of which of the buttons has been used in the External Link Manager. If the file is closed without saving, the links will still be there the next time the file is opened, which is also very useful if you broke some of the links by mistake!
The option Unlink Children Parts is checked when breaking the link for a subset, if you want all links for the parts below to be broken at the same time.
This option quickly breaks the links for all objects in the entire 3D scene. Here too, it is important to close the tool and save the scene immediately afterward.
With this option, you can save an externally linked file to another folder or under a different name. Remember to save the 3D scene after closing the tool if you have resaved the external link!
With this option, you can select an object and replace it with another file. The placement of the new file is determined by its anchor point, which will assume the same position and orientation as the replaced object's anchor point. Remember to save the 3D scene after closing the tool if you have replaced the external link!
Opens the selected part/assembly in its own file.
Saves the selected part/smst to its own file. This option is very useful if you have a problem with some external link being corrupt or behind save problems in the main assembly. By selecting one half of the files in the tree and saving via this button and then doing the same for the other half, you can eliminate the source of the error behind the problem saving the main assembly.
The Not Linked tab displays all unlinked parts and assemblys in the 3D scene. There is also the possibility to select and save as an external link. Remember to save the 3D scene after closing the tool, if you have saved new external links!
