CAD is not only what I do for my profession, I also do it for fun. For personal projects, I have been having a great time with using FreeCAD, a very capable and feature-full parametric modeler. With a recent resurgence of Legos in my house and falling into some web-searching rabbit holes, I stumbled upon this Lego CAD software called LeoCAD. I am currently using the AppImage on openSUSE that works fantastically well. I’m sure it will work on any modern Linux Distribution. It is also available for those “other” platforms. It can be downloaded from here:
https://www.leocad.org/download.html
The nice thing about AppImages is that there is nothing to do to install it. I created a folder where I keep all my AppImage files. Using Dolphin, I made the .AppImage executable so that you can just double-click to execute the file and run LeoCAD.
Um… Why?
Beyond the cool factor of creating Legos in virtual space or loading up those childhood models and modifying them in ways that you didn’t have the parts for as a child, there are lessons you can teach kids with this software.
LeoCAD is not only an extremely enjoyable toy but it is a great tool for teaching my kids the principles of Assembly, Sub-Assembly and Master Assemblies and the some understandings of spacial relations. At the very basic level, using LeoCAD to create, you are putting pieces together to create a very basic “assembly” or model.
To put together a model you create it, much like in real life, piece by piece. There is an extensive library of parts from which to choose. You can search through by category or use the part numbers to more rapidly locate what it is that you need. Those parts can be colored from what you see in the pallet which are, from my understanding, actual Lego colors. Here is a fun fact. On Legos that are made in the 1990s-ish or newer, will have a part number molded into each part on a “non visual” surface. If your eyes are older… you might need a magnifying glass.
Another very cool feature of LeoCAD is the ability to order steps on a model. If you have a desire to create your very own instruction booklet, that can be done with LeoCAD.
Once you have created a Sub-Assembly, or as LeoCAD calls them, “Submodel” you can bring each Assembly / model in together in a “Master Assembly”.
Any assemblies or Submodels can be treated like any other Lego part. Objects are objects whether they are individual pieces or Submodels.
For whatever Submodel Tab you have selected, you can view the parts used by selecting: Submodel > Properties… then select the “Parts Used” tab. This gives you a complete list of all the individual pieces you have used in your model. If you so choose, you can take this list and purchase the necessary pieces to build your creation.
Unfortunately, I was unable to find a way to export this list into a spreadsheet, so that does complicate matters somewhat.
If you want to download some Lego Sets to spin around LeoCAD, check out the Ldraw site. You will need to know the set number to look up to get the CAD files. If you would like to look at this the previously pictured Blacktron Invader, from 1987, see here.
Lego Project
After some playing with LeoCAD, my boy and I began talking about what we should build. We are both fans of Star Wars and he liked all these old 1980s themed Lego space sets so we decided to put two of them together and made a “Blacktron AT-ST”. It was a good way to go head-first in really learning and understanding this software and it’s quirks.
Just building the model in LeoCAD took about a week of work. That was a few hours here and there. Much of the time spent was learning how to effectively navigate the software and fine the proper parts in the library. The actual assembly process of the pieces is pretty intuitive. You do have to play with the snap points when doing less common assembly angles but it is in no way difficult. This was probably a bit too ambitious for a first project but it was completed. There are a total of 428 parts divided into 24 submodels one of which is the Master Assembly (submodel) that all the individual models assemble into.
We took the parts list and went through the Legos we had to determine what was on hand, then we put the rest into a “wishlist” on Bricklink.com where we were then able to order the parts necessary to build it. My boy used this an entry for a craft project for the local county fair. It was fun for the both of us. Maybe me more so than him but this application along with the resources through the Internet is essentially a childhood fantasy come reality.
I want to note that this is not in any way an original design. This is heavily based on an actual licensed model and essentially recolored to look like it could fit with the rest of the Blacktron theme. Now, it is just another Lego model toy on our Lego table.
What I like
Assembling Legos in the virtual space, although not as satisfying as the snap of the genuine article, is fun and can really allow you to flesh out some ideas somewhat rapidly. The benefit is, you can take that virtual model and turn it into a real model.
Another thing I like to do with LeoCAD is documenting changes I make to a design. If I come up with an idea, I like it, I can make it in the LeoCAD and date stamp it. This way, I have the freedom to make the changes to the real model and I have a point I can go back to as a reference.
LeoCAD is very fast and snappy using only the Intel GPU. I have run it on my AMD GPU as well as and I am sure it is performing better but not so much that I can tell the difference.
It is easy to change the colors of parts of the Legos and if you are doing a virtual prototype, it is much easier to swap out the colors of parts on LeoCAD than it it is with Actual Legos.
There are all kinds of 3D models to download, look at and modify to your hearts content from Ldraw.org. If you need to look up set numbers, use this resource: brickset.com.
What I don’t Like
There isn’t much to not like about this software. There are only two issues that I have with it. There is no way to export the Bill of Material / Parts list to any kind of file. Even a way to export to CSV would be fantastic. As it stands today, you can copy only one cell at a time. Hopefully there will be an export feature in the future.
There is no collision detection between parts and pieces. So, it is possible to bury parts within parts. Some kind of “align” and “orient” option would be great too when assembling components.
Lastly, and really, least important, the UI is too light. I would prefer a dark theme. Not a big deal but it would be nice.
Final Thoughts
LeoCAD is not only a great tool for teaching the concepts of Computer Aided Design but it is an incredibly fun toy with which to play. I didn’t realize what kind of fun-spiral I could fall into. LeoCAD is an incredibly useful tool to teach CAD and many CAD concepts.
If you have a passing interest in Legos or CAD or both, this is worth checking out. Opening up Lego models from your childhood, spinning them around and modifying them like you would have done so many years ago is a great way to spend a weekend where the weather isn’t cooperative. Being able to create, modify and document your ideas is fantastic but the best part about LeoCAD is, at no time will playing with these Legos pose any risk to your feet.
Further Reading
LDraw.org, open standard for LEGO® CAD programs
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