CAD for VEX™ Robotics Kits

Although use of this information and these parts is free, please consider contributing at least your first model/instructions back to for the Robots page.

Robot .ldr files can be emailed to webmaster AT hobbyvex DOT org for posting on this website.

CAD Thread on VexForum

The basis of this endeavor is the excellent and free MLCAD program.  Starting with the files on the site and with a whole lot of help from a friend creating missing parts, a very usable set has already been converted for use within MLCAD using the awesome stl2dat.exe program.  MLCAD is part of the LDRAW set of tools which includes the ability to turn a model into a nearly professionally drawn instruction set.

New Parts!

The 2.0 version of the parts is now ready!

Many thanks go again to my friend for helping me figure out how to use SolidWorks. Thanks also go to the folks at the Robotics Academy for allowing the use of their SolidWorks models as the basis for some of my parts. You can find their originals at their Vex Curriculum page.

Unfortunately, the 2.0 parts are not compatible with those in the 1.0 package. Some of the previous parts have been replaced. Many new parts have been added (77 total.) All of the files have been renamed to be compatible with the 8.3 naming requirements in the package. The part names visible in MLCad have been modified to organize the parts better. With 77 parts it is very helpful to do that.

The good news is that I wrote a script to rename all the old parts to their new names. With a little work you can convert all old files to the new parts easily. If you have models based on the old parts, go to this page for update instructions.

For version 2.0, I decided that small size and fast load time was more important than photo-realistic rendering. I put quite a bit of effort into cutting these parts down to size. However, that means that they will not always look exactly like the original parts. In particular, the wheels look nothing like the real wheels. On the other hand, MLCad loads all 77 parts in under a minute on my machine. There may be a way to swap higher fidelity parts into a completed model. Send email to webmaster AT hobbyvex DOT org if you care about this. I'm going to assume low fidelity is just fine if nobody sends email :-)

The Parts

  1. Get and install the LDRAW package. Click on the getting started icon at the top of the page and follow the directions.

    NOTE: If your installer is not 47.3 MB you will need to restart your download to get the rest of it or else start all over downloading it.

  2. Get the most recent version of MLCAD and install it.
  3. Get the file and unzip it into the LDRAW install directory (as a sibling of Parts).
  4. In the LDRAW/Apps/MLCAD directory, update the mlcad.ini file by modifying the [SCAN ORDER] section to include the VexParts directory
  5. NOTE: If your installation does not have an mlcad.ini file in the mlcad directory, you can get a copy of it here. If you don't see file extensions like ".ini" you can either turn that on in your OS or look for a file type of "Configurations".

    NOTE: The new parts have different filenames that conform to 8.3 naming. See the instructions on updating if you need to convert an old model to the 2.0 parts.

  6. In MLCAD, right click on the parts tree, select "parts tree" --> "tree configuration..." and add a rule for "Vex" with search string "<Vex" and move it to the top of the list.  Then, use the file menu to "Scan Parts".  You should now see a node for "Vex" at the top of the parts tree and all of the VEX Robotics Kit parts in the display pane.
  7. In MLCAD, choose the finest grid setting for placing parts. You can use the Settings menu and choose the Grid flyout menu and then choose Fine -or- press F11 -or- find the grid icon on the toolbar and press it. Using the finest grid setting helps when positioning parts because the snap-to-grid feature can get closer to where you want the part to be.
  8. Drag either a part name from the tree or its picture from the display pane into one of the building panes to start your model.
  9. To place a part where you want it, it helps to pull it into one of the panes a bit off from where it should be finally placed. Then, put your mouse right over the cross-hair in the center of the part and move that to the center of your target position. By putting the part off to the side initially, you can see both the cross-hair and the target location before and during the drag into position. Don't forget to repeat this procedure for the third dimension!
  10. As you complete logical subunits, insert STEP lines in your model. Each step can later be rendered as a separate image in your building instructions.
  11. Don't forget to send your models back to for sharing! Please send an email to webmaster A T hobbyvex D O T org if you decide to use this work. I won't spam you but it would help to know people are using it.

New Parts

Send an email to webmaster AT hobbyvex DOT org. I hope to get around to posting them in the not too distant future.

Here are the STL Sources for the 2.0 parts.  The SLDPRT files are still not ready.

Thanks to the folks at for providing a number of models on their site.  A special thanks also to my friend for creating all the other parts in the set!!  If you would like to help create new parts or you know how to improve the existing parts, please dive right in.  Send any updates to webmaster A T hobbyvex D O T org.  Go to the stl2dat.exe page for the converter tool and instructions on its use.  In the end, we created STL files with a base unit of millimeters and then I used this script to convert them to properly scaled LDRAW dat files.


Help on the use of MLCAD can be found here.  Creating a model for the VEX Robotics Kit is exactly the same as a Lego™ model except for the parts used.  There are also instructions out there on how to create professional looking building instructions, but I haven't had time to go through those yet.  Look for further postings as time permits.

Once you have built your model, you can create quick and dirty building instructions by going to the File menu and choosing "Save Image(s)...". An image will be generated for each STEP you insert in your model and saved in the directory the model lives in (<LDRAW>/Models by default.)

Similarly, a parts list can be generated by going to the File menu and choosing "Save Parts List...". You can save the overall parts list or have it broken down by step. This file is also saved with your model.