Archive for the ‘Computer-Aided Design (CAD)’ Category

LPub 4 for Windows and Mac OS X

Monday, July 14th, 2008

Kevin Clague has released version 4 of his popular LPub program, which is an “LDraw Building Instruction Publishing Tool.” You can download LPub 4 from his website; the program is now compatible with both Windows and Mac OS X. You can see a screen-shot below of the new LPub (the LDraw model shown is made by Allen Smith and included with Bricksmith). I used an earlier version of LPub to generate the building instructions for The Inventor’s Guide and am excited to see this latest version. Creating building instructions is a much easier task with tools like LPub!

LPub 4

Updated Tutorial for Creating Virtual NXT Robots

Saturday, March 22nd, 2008

Through some helpful reader feedback and advice from Philo, I’ve updated my tutorial for setting up the LDraw system to create virtual NXT robots. Click here to check out the revised post. Comments welcome! Let me know how to make this even easier or if you’d like to see instructions for setting up additional features.


Tutorial: Setting up LDraw to Create Virtual NXT Robots

Sunday, January 20th, 2008

I used the free LDraw system of tools to create most of the images and all of the building instructions in the ULMN Inventor’s Guide. If you’re interested in learning how to create virtual NXT robots as well, the following tutorial shows how to set up LDraw on your computer and customize it specifically for NXT parts.

Note that the most commonly used LDraw tool for creating models is the program MLCad (see image below). To facilitate the process of finding and selecting parts from the NXT set within MLCad, I’ve customized a “favorites” file used by MLCad, listing all the pieces in the retail version of the NXT set. The pieces are listed in the same order as found in Appendix A (LEGO MINDSTORMS NXT Piece Library) of the ULMN Inventor’s Guide. You’ll use this customized file in the tutorial.


Setting Up LDraw to Create Virtual NXT Models (for Windows users)

Note: If you already have LDraw and MLCad installed, skip to step 2.

Step 1: Download the LDraw Tools Installer from the LDraw website. Once downloaded, open the file and follow the instructions. You can choose “Basic,” “Intermediate,” or “Advanced” installation. For this tutorial, only “Basic” is necessary (which includes the installation of MLCad).

Step 2: Download the Unofficial Part Files from the LDraw website. Although you don’t need all of the unofficial files, you’re going to download everything at once to make it easy. You’ll download a single zipped folder, and when you unzip the folder, make sure to extract the files to your C:\LDraw directory. If you’re using Windows XP, you would unzip or extract the folder’s contents by right-clicking the zipped folder and selecting “Extract All…”

Step 3: Go to and download the 24 bits stone color version of the LDraw NXT parts. Even though you already got these parts when you downloaded the unofficial part files in step 2, you want to use the modified color settings of Philo. After downloading the zipped folder, extract or unzip the folder’s contents to your C:\LDraw directory. You’ll be asked if you want to overwrite the existing files–select “Yes” or “Yes to all.”

Step 4: Download the customized MLC_Favorites file by right-clicking on this link and saving the file to your C:\LDraw\Apps\MLCad directory. Since you are replacing an existing favorites files, you’ll be asked if you want to overwrite it–select “Yes.” Note: If you have already added favorite pieces within MLCad and want to keep them, you can copy and paste the contents of my file into your existing MLC_Favorites file.

Step 5: Run MLCad and selecte File –> Scan Parts from the menu bar. MLCad might take a little while as it scans for new parts, and when it’s finished, it should ask you if you want to create a new Parts.lst file–select “Yes.” Finally, click “Favorites” from the list on the mid-left of MLCad. All the NXT set parts should appear below (see following image). Have fun! The best place to get more information about using LDraw is the website.


Hints and Tips:

1. Many of the pieces in the NXT set use the new “stone” colors (i.e., light stone gray, medium stone gray, and dark stone gray). When you want to change the color of a piece—the default is black—enter one of the following values as a color number in MLCad:

Light stone gray: 0x02E5E4DE

Medium stone gray: 0x02A3A2A4

Dark stone gray: 0x02635F61

2. For now, the best way to add electrical cables is to use the “RJ12 Cable End” part. This part is simply the end of an NXT cable and signifies a complete cable (and prevents your model from looking messy!).

3. The turntable in the NXT set exists as two parts in LDraw (the “top” and the “base”). Simply put the parts together in the workspace in order to achieve a complete turntable.

LEGO Digital Designer (LDD) Version 2.3

Friday, December 14th, 2007

Creating building instructions for NXT robots can be a lot of fun. And it’s a great way to “preserve” your robots after you’ve taken them apart. There are now a variety of ways to create virtual NXT robots and building instructions, but a quick and easy way to begin for either Windows or Mac OS X users is with the official and free LEGO Digital Designer (LDD) software. Since the capability to create NXT robots with LDD is relatively new, there are still some bugs to work out. But it does work. Version 2.3 of LDD was recently released, and you can visit to download the latest version.

Note that I did not use LDD to create the building instructions in The Unofficial LEGO MINDSTORMS NXT Inventor’s Guide. Rather, for my book I used a set of tools based on the LDraw system.

LEGO Digital Designer