Cardboard to CAD

I discussed how I was able to gain clearance for my hood and battery box in the Good Under the Hood post but now I had to turn my attention to holding it up when open. The factory support is a large complex torsion tube that runs the entire width of the engine compartment. Because it goes across the entire engine compartment it would hit my battery box. Plus, it is complex, dangerous, hard to paint, etc. and Paul had already figured out the geometry of switching to modern gas struts instead.

Original hood prop system has torsion springs in a tube with arms (all the black stuff)

Paul's car swapped to simple, lightweight gas struts

I didn't love the welded brackets on Paul's car so I made a cardboard template to locate the pivot point and used that to make a model in CAD. Instead of requiring welding, my bracket is designed to bolt onto the hood in the original torsion bar locations.

Cardboard template, hand drawing, 3D printed prototype

The sketch of the bracket in Fusion 360 CAD

Once I had the part designed in Fusion 360 I exported it to my 3D printer and printed out a prototype to test fitment. Once I verified that they worked as expected, I exported the CAD drawing to sendcutsend.com to have them laser cut from 1/4" thick T6061 aluminum. I also designed some small tabs for the other end of the struts. Those I had cut from steel and welded to the inner fender aprons.

3D printed prototypes with stainless threaded ball studs

I sketched up the steel tabs in CAD also

Total cost to cut out via Send-Cut-Send: $30 (and that's with 2 extra tabs, just in case -- the minimum order is $29)

See below for a video of the process from cardboard to the final result.

This was an eye opener for me. Up until now we've fabricated all our own parts using the plasma torch, saws, grinders, welders, etc. This was much easier. The elapsed time is longer but it results in perfect parts that are tested, identical, pretty, light, etc. And cost less too. SendCutSend's $30 represents less than half an hour of in-shop fabrication time. Add $51 for the struts (17" long, 40 pound units by the way) and this was an under $100 modification well worth the effort. End result: clean, light, simple. Very pleased. My CAD skills are improving and I plan to do more and more parts this way.

The test fit was almost perfect the first time. I added some fillets to round the corners and reduced the dimensions by about 1/8" in the final drawing