Tuesday, August 31, 2010

What does a CAD Technician do?

Are you thinking about getting into computer modeling or design work? CAD technicians are typical entry level positions throughout the industry. The CAD Technician works as a member of a team that is responsible for modeling and detailing activity associated with engineering services.


The following duties and responsibilities are illustrative of the primary functions of this position and are not intended to be all-inclusive.

CAD Technicians must have ability to:

  • Operate computer and effectively use various CAD software packages, including CATIA V5, Siemens' UG-NX, SolidWorks, Pro/E, AutoCAD, etc.
  • Generate 3D models of parts and assemblies
  • Perform meshing for analysis
  • Effectively communicate CAD model creation and conversion related issues or concerns. These would include model design, software issues or complex attribution.
  • Track own progress against bid hours using sources available to ensure project deadlines are met



  • Previous CAD experience a plus but not required
  • Good basic computer skills
  • Ability to pay close attention to detail and work accurately
  • Ability to work effectively as a team member
  • Be flexible to cross-train and work on various projects as needed
  • Be self-directed to pace own work and meet necessary project deadlines
  • Good verbal communication skills
  • Ability to establish and maintain effective working relationships with other CAD Technicians, manager, supervisor and other staff
  • Willingness to continuously learn different aspects of CAD-type applications
  • Understanding of engineering drawings and legacy CAD digital files a plus
  • Bachelor's degree in related field a plus

Monday, August 30, 2010

How do you create high quality model renderings in CATIA V5?

CATIA V5 users may be wondering how do you create a high resolution image of their CAD model? The quickest way to render an image of a model in CATIA is by going to Start>Infrastructure>Photo Studio--> quick rendering. Although this is drastically better than just taking a screen shot, it isn't really a high quality resolution image that you may want to use for a poster or marketing device. So how do you produce a really high resolution picture?

Go to Start>Infrastructure>Photo Studio. Next, click on the "Create Shooting" icon. A window will pop up and the first tab should be "frame." There should be an option that says "image size". Move the slider bar to a higher level on the right as this changes the pixels. Typical size for a poster is 1600 x 1200.

Also, you can go through the other tabs to refine what you want in your picture by setting many of the other options, including various lighting packages. There is even a "cartoon" view!

To obtain your final image click on the "Render Shooting" icon, located under the "Create Shooting" icon. It takes a little longer to render the image this way but it's worth it. Quality over quantity every time! This is also another way to render video simulations from the kinematics workbench. It even lets you chose a camera view to use (like if you are modeling a roller coaster and want to take a POV ride). I hope this helps you render high quality screen captures!

Monday, August 23, 2010

How to simulate rolling with CATIA DMU Kinematics?

Slide 1
A reader recently asked if I could put together a tutorial for the kinematics rolling simulation that I created. This may not be extremely detailed but should give you a pretty good idea of the steps to take when trying to simulate rolling in CATIA. This was one of the preliminary tests I ran before attempting to simulate my entire roller coaster model.

(Download the rolling in kinematocs tutorial here)

Every time you use kinematics something needs to be fixed, so the rest of the assembly moves in relation to the fixed part. In this case, the track will be fixed. Set the assembly up in assembly design then switch to the DMU Kinematics workbench when you are ready to begin simulating. You can see the constraints I used in the screen shot. It is very important to pay attention to the degrees of freedom of the system. When dealing with large assemblies, I often fully constrain the entire assembly and then go back in later and delete the constraints where I want a part to be able to move, in order to not be confused. 

Slide 2
Here are the joints I used to create the connected wheel rolling kinematics simulation.  To create these constraints, click “Assembly Constraints Conversion” wizard.  Create a new mechanism then click “Auto Create” and it will automatically create joints based on the constraints in the assembly. Next, you need to manually create the roll curve joints between the wheels and the track.
 Slide 3
In order to create a roll curve joint you must have two curves that are tangent to one another. Here, you can see the sketch on the wheels is tangent to the sketch on the corner of the track. Double click on one of the roll curve joints and toggle the “Length Driven” option. This is your input. After you click ok you should get a message that reads “The machanism can now be simulated” and the degrees of freedom of the system  (DOF) should be zero.
Slide 4
In order to apply gravity to your simulation you need to create a sketch  called a “trace law.” This is essentially a graph of distance which respect to time, with the horizontal axis being time and the vertical axis being distance. A straight line gives a linear relationship, or a constant speed. Change the graph to an exponential curve and you now have acceleration.

Now you should be able to simulate two connected wheels rolling down a hill with gravity. Any questions?

Thursday, August 19, 2010

Steel Roller Coaster Modeled in CATIA V5

As you can see from many of my previous posts, I spend quite a bit of time modeling roller coasters in CATIA. Well, it looks like I'm not the only one. Yunus Alapan, a student at Yildiz Technical University in Istanbul, Turkey, recently submitted a few pictures of a roller coaster he created with CATIA V5. I know from experience how hard and time consuming  it is to model a complete roller coaster by yourself, piece by piece. Hopefully, one day we will see some cars running around the track. Good job Yunus!

And since we are on the topic of CAD coasters, check out my latest simulation of the Cantilevered Roller Coaster. This time I show case the “side knocker” effect! More kinematics experimentation on the CRC model with a mismatch of new and old parts.

Tuesday, August 10, 2010

New 3D XML Model Uploaded to 3D Via

Today, I uploaded a new CAD model to 3D Via in 3D XML format. This is the current state of my next generation version of the cantilevered roller coaster. The main difference has been the change from a cantilevered I beam to a beefier truss configuration.

Wednesday, August 4, 2010

CATIA Kinematics Simulation from Manikin's POV

I am modeling a new type of roller coaster in CATIA. In order to test this new coaster concept I need to run the simulation from the viewpoint of the manikin riding in the car. Whether you are modeling a roller coaster or a sports car, here is how it is done:

First, make sure this option under Tools > Options>Ergonomics is set:

For the line of sight, create a camera in View - Named View and  then position it close to your manikin head.

 Next, attach the camera to the head of the manikin with the "attach/detach" function and change the property to perspective.

You can open a camera view window while in DMU Nav by using the Window Menu, you can open the Camera window:
Use this Camera window for recording.

 The only downside is when I simulate in the camera view it automatically switches the geometry to "shading with edges" instead of what I want to see, which is "shading with material." Anyone know if there is an option somewhere to change this?