Reverse Engineering a Jeep Wrangler 2005 Auxiliary Light Bracket Mount with 3D Scanning

THE PROBLEM: The Jeep Wrangler auxiliary light bracket mount had a stress fracture thus needed to be replaced.

THE CHALLENGE: Reverse Engineer the Jeep Wrangler auxiliary light bracket mount and make it stronger than the original bracket mount using the latest 3D scanning and 3D printing technologies.

1. Background

Chris loves driving around Lake Tahoe in his open-top Jeep Wrangler, enjoying the blue skies and fresh air. The Jeep Wrangler is his vehicle of choice for fun adventures and transporting his wet dog after a swim in the lake. One day, Chris noticed that one of the auxiliary light mount brackets at the front had cracked. Initially, he planned to search for replacement parts, but then he heard about Growshapes' 3D scanning technology. Intrigued by the idea of reverse engineering and 3D printing the bracket, he contacted Growshapes to explore the possibilities. The original bracket mounts were made of plastic and had cracked under stress, so Chris was looking for a solution that would be stronger and more durable than the originals.

​2. The Tools and Method

Growshapes used Einscan Pro 2X 2020 to 3D scan the cracked plastic bracket mount and worked with an engineer at Uniformity Labs to reverse engineer and create a metal 3D-printed replica.

3. The Reverse Engineering Process

Step 1: 3D scan the bracket mount to capture complex geometries using Einscan Pro 2X 2020

Growshapes received the broken plastic bracket mount from Chris. Judging from the size of the part, we decided the best scanning tool was the EinScan Pro 2X 2020 that can capture intricate details with high accuracy, especially in fixed scan mode using it in conjunction with the automated turntable.  For small objects, EinScan Pro 2X is the way to go for sure.  It captures fine details as point cloud data, then converts it into a mesh that can be exported as an .stl file into a CAD software such as Solidworks. 

Growshapes 3D scanned the black plastic part that had a fracture on the main wall of the bracket mount. You can see the fracture in the scan results below.  We scanned the bracket in fixed mode to digitally capture accurate data of this small part.  Fixed scan mode was chosen to use the 3D scanner with the automated turntable. There was no need to put any markers on the parts as the scan was aligned to the markers on the turntable and didn’t even require spraying even though the part was black. The Einscan Pro 2X 2020 uses structured white light technology and the software allows for the capture of dark parts.

3D scan of the bracket

3D scan STL file

jeep_bracket.stl
File Size:	52799 kb
File Type:	stl

Download File

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Step 2: Reverse Engineering

We required expert knowledge rather than simply converting the 3D scan data into a solid model in CAD as the output was going to use additive manufacturing technology, and 3D printed metal. Therefore Growshapes worked with an expert at Uniformity Labs to create the output required. Groweshapes sent the raw scan data in .stl file format to Marlon. Marlon, who led Application Engineering at Uniformity Labs started the reverse engineering process by importing the .stl file of the original design that Growhapes 3D scanned into his CAD software Solidworks.  For Marlon, extracting the geometry data from scan data was easier and required less time than measuring the bracket with calipers as it gave accurate values quickly. Furthermore in the CAD software, Marlon was able to model directly over the scan using it as a constant reference. The key expertise Marlon added further was optimizing the design for additive manufacturing in metal, i.e. removing as much material as possible while ensuring strengths which results in adding lattice design.  

The steps that were taken from editing the scan files to  print:

1. The scan was imported into CAD software as points and surfaces
2. Measurements were collected and construction geometry such as planes, contours, etc. were extracted from the scan data
3. The bracket was modeled from this reference geometry generated by the scanned data
4. That design was then "optimized" for additive manufacturing, removing as much material as possible, adding lattices
5. The optimized design was exported from CAD as an STL file
6. The STL file was sliced in Netfabb using the latest EBPA
7. The SLM 125 (for AlSi10Mg) and SLM 280 (for 316L) were prepared and the prints launched
8. The builds were removed from the machine, cut off of the build plate, and sonicated
9. Supports were removed by hand

Some of the challenges Marlon faced specifically for optimizing for additive manufacturing:

• Required other software beyond just the CAD software. Other software, such as nTopology, simplifies modeling more organic shapes conducive to additive manufacturing
• Limited information about the end use of the bracket (how much it was going to support, environmental conditions, etc thus had to make assumptions

Things specifically engineered to optimize for 3D printing:

• Material removal for light weighting
• Lattices for additional stiffness
• Kept overhangs to 45 degrees to minimize support and post-processing
• Made assumptions regarding loading and boundary conditions

The original bracket was made from injection molded plastic but the plastic gave way to stress over time. The metal bracket should be stronger than the original plastic bracket mounts.  Marlon decided to use 316L (stainless steel) as is resistant to corrosion in harsh weather and can withstand varying temperatures. Injection molding requires a substantial investment in tooling thus requires volume production but with additive manufacturing, one-off print is possible with drastically shorter lead times. 
​
See the full additive manufacturing workflow​ below:

Courtesy of Uniformity Labs

Chris is happy with the new and improved auxiliary light bracket mount that is stronger than the original one that came with the Jeep Wrangler.  He won't have to worry about having another stress fracture in the bracket mount.  Reverse Engineering is not just about replicating but also about improving upon the original design!  

Check out the mounting brackets that were fixed onto the Jeep Wrangler below.

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