Design for Manufacturability
With the power of modern 3D modeling programs, the difficult part is in the manufacturing of the final design. As the old saying goes, “it worked on paper!” For our project we decided to place as much emphasis on engineering the manufacturing process as possible, especially for precision and repeatability.
In addition to the chassis table and jigs, we used paper templates and detailed manufacturing drawings to bride the gap from modeling to fabrication.The paper templates were created by treating each tube as a sheet-metal part. We drew a seam down the center and used Solidworks sheet-metal function to make a flat pattern and extract the templates for the copes. The copes were then printed on a 1:1 scale, cut along the seam lines, and used to mark the tube ends. And example of a paper templet is seen below in figure 1.
Figure 1: Paper templet for tube fitment.
Jigs for the chassis tubing
The jigs were designed to be assembled with minimal use of squares and levels. The accuracy of the CNC plasma table allowed us to create brackets/jigs that interlock, ensuring squareness and strength. For more information on the jigs please visit the Jigs Page.
Figure 2: Jig mounted to the table prior to welding.
Figure 3: Jigs were designed to square themselves by interlocking together. This saved valuable time and improved accuracy.
Section 1
The chassis is being built in 3 sections similar to how ships are built. We chose to do it this way for ease of manufacturing and accuracy. By creating each section separately we also were able to cut down on compiling error in the chassis tolerances. See Figures 4 and 5.
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Figure 4: Beginning of stage 1. Stage 1 consist of the top 1/2 of the chassis.
Figure 5: Beginning of stage 1 viewed from the front.
A-C Pillars
The A-C pillars in the chassis are the most complex tubes with three bends. One of which is non-planar to the other two. This required us to rotate the tube in the bender to the exact angle.
Figure 6: A-C pillars in place with jigs assuring their placement is accurate to the model.
Notching Tube
The chassis was designed with triangulation and transferring of forces in mind. As a result many of the notches require hand grinding to mate up perfectly to the nodes.
Figure 7: James Wray hand notching tube with and angle grinder.
Figure 8: A hole saw “notcher” makes quick work of the less complex notches.
Figure 9: The Baileigh notcher allows us to notch complex and high angles quickly.
Clamping Tubes
Clamping the top of the tubes in place allows us to weld with minimal deflection and assure the tubes are in the correct location.
The first few front tubes are in.
Inspection and Welding
Each tube was inspected for accuracy and welded in place while still held in the jig. All welding was conducted using 0.35 wire and a Lincoln Electric 216 wire feed MIG welder.
