Tales From the Engineering Intern: If at First You Don’t Succeed, Design, Design Again

3D-Printed Center Console Dodge Hellcat

Airwolf 3D Design Intern Prescott Campbell shares his design process for his most difficult assignment yet: Redesign the Dodge Challenger SRT Hellcat’s Center Shift Console to provide extra storage space and custom vanity branding. Find out how Prescott overcame design challenges — and learned some lessons along the way — in order to create what has become both a Wolfpack- and crowd-favorite custom car part unveiled as part of the “World’s Most 3D-Printed Hellcat” at SEMA 2017.

The 3D-Printed Center Console Challenge

My latest project here at Airwolf 3D is a 3D-printed center console panel for Airwolf 3D’s Dodge SRT Challenger Hellcat. This was by far the most difficult part I have ever designed due to the abstract and organic shape of its border. The parts I have replaced in the past have all had features that were relatively geometric, making it easier to measure and recreate in SolidWorks. If I printed one of those parts and it didn’t fit in the car, I could easily tell which feature was the problem, and how to change the dimension to fix it. I soon learned that would not be the case for this part.

This part has an amoeba-like shape, and I really couldn’t find a good place to measure the dimensions of the part. My solution was to place the stock part top-down on a piece of paper and trace around the outside. I then marked points along this trace line and chose a corner of the paper as the “origin.” I measured the coordinates of each of the points relative to this origin and marked my measurements by their corresponding points.

3D Design Notebook

I then made a sketch in SolidWorks where I placed points the same distances relative to the origin in the program. I used the “spline tool” to then connect all the points together in a smooth shape.

Spline Tool in SolidWorks
The Spline Tool in SolidWorks was used to create the outer shape of the part.

I extruded the sketch into a 1-inch thick “ring” where the outer edge would represent the shape of a full part. I did not create the entire part yet because it wouldn’t be as quick to print and test every time I made changes. I’m glad I did this because I was able to make several versions of the part and test them in the same day. In APEX, I used the Standard ABS settings so the parts would print relatively quickly and still be very accurate. I made 10 versions of the ring, but never quite got the shape right.

Student Prototypes
Despite multiple versions, the “outer ring” created as a test-part never came out quite right.

New Knowledge, New Plan

I decided that my method was inefficient because I never got the correct shape after that many attempts. I did some research to try to find a more accurate way to recreate this shape. What I found was that it is possible to load photos in SolidWorks, so I came up with a plan: Trace the part on copy paper, scan it, and then load the .pdf file in SolidWorks. I never considered loading an image in SolidWorks before, much less actually done it, so I watched a tutorial to learn how to use the technique.

Once the image was scanned and uploaded in the program, I traced the image of the scanned shape using the spline tool. I then used this sketch to make the same types of rings I did before. Since the image was not a 1:1 scale with the real-life part, I had to to scale it down. It took a few tries to get the size right, but I finally got the ring to fit.

It was now time to design the rest of the part, which included another abstract shape: the insert for the shifter boot. I used the same plan to make this feature as well. Again using APEX’s Standard ABS settings for these prints, it only took a couple tries to get this feature right.

I also designed the storage compartment of this console piece. I wanted to make this larger than the stock part, but had to make sure it didn’t interfere with anything below it. There is mostly electronics underneath the panel, and I had to measure how far down these parts were. I realized that the factory part was already made about as deep as possible, but not as large as possible. I wrapped my “pocket” around the shape of the boot, and added the Airwolf 3D Logo.

Student SolidWorks

Student SolidWorks Design
After some troubleshooting and a SolidWorks tutorial, the console design started to come together.

I finally got the full part to fit!

3D-Printed Prototype Automotive
Success! The upper portion of the console liner fit and it was time to work on making the part snap securely in to place.

What to Do When Tab Design Isn’t a ‘Snap’

Now I just needed to make a way to have the part fit securely and stay in place. Airwolf 3D CEO Erick Wolf suggested designing snap-fitting tabs for this. This involved making a feature that would have to flex, something else I had never done before. I attempted to design tabs, and again only on a ring instead of a full part. My first design was not successful.

Student Prototype in Solidworks

Create Tab in SolidWorks
The initial, and unsuccessful, tab design.

In order for the part to snap in properly, the tabs needed more flex. As it stood, the tabs broke before they were able to flex far enough to snap into place. I asked Polo Delgado, Fabrication Technician and SolidWorks engineer at Airwolf 3D, for help on designing the tabs. He sent me an article on snap fit design. After reading it, I set to work on redesigning the tabs.

Printed Prototype Automotive

Design Tab Car Solidworks

Designing Tabs SolidWorks
Tapering the arm of the tab helped provide the strength and flexibility needed to allow the tabs to flex enough to snap securely into place.

New Design + Optimized 3D Printing Settings = Success!

I printed the tabs using APEX’s Precise ABS settings and increased the shell thickness to quadruple the preset. The Precise settings ensured that the thin tabs would print cleanly, and the thicker shell would allow the tabs to flex further without breaking. This time, the tabs worked perfectly!

3D Printed Tab
The new tab design, 3D-printed and ready for testing.

I put my tabs onto the full part design and the part was finally finished! After some trial and error, the company’s project car had a new center console that fit perfectly, offered extra storage, and showcased the Airwolf 3D logo.

ABOUT PRESCOTT

Airwolf 3D Intern Prescott Campbell is a junior at Corona Del Mar High School in Newport Beach, CA. With his passion for cars and experience using Airwolf 3D printers with his school’s robotics team, Prescott joined the Wolfpack to help work on custom 3D-printed parts for the Dodge SRT Hellcat Challenger.

Student Automotive Design
The final result: a redesigned center shift console that features deeper wells for storage and an Airwolf 3D logo.

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