Side Mission: Replica Team Associated SC10 Nerf Bars

[Spksh]

Let's play spot the difference.

Despite what you might think, only one of those is a banana. The other is a seriously bent SC10 nerf bar. It's hard to make out in the picture, but it's actually warped in 3 dimensions, which feels like some kind of achievement. But! I can't use it (or the banana) on The Most Interesting SC10 in the World, it just wouldn't be right.

I tried a heat gun, but the plastic only seems to have a memory of being a banana in a past life, and it keeps cooling back to the same bent state.

So, what's a poor boy to do? Well, given a 3D printer, and that some absolute legend modeled an entire SC10 in CAD (including screws), I think I have a plan.

 

[Spksh]

So a first approach would be to just print it as-is with some supports.

But guess what happens when you do this to a 3D print?

Sad trombone. Our chassis side hook flange thing just snaps at the layer lines. Now, you could reorient the print and get strength along the axis of stress for that one area, but then you'd have layer lines perpendicular to the ground; the nerf bar itself would have no strength.

 

[Spksh]

Alright, so let's separate the flange clip thing from the body of the nerf bar, so we can print them both in their optimum orientations, so the strands of the print lines align with the forces we'll be applying. Bonus points for avoiding the whole "twist and flex" nonsense.

I need some kind of clip arrangement, with some draft to really clamp down, and a corresponding slot in the nerf bar.

Tolerances are very important, so we iterate.

And we get something pretty close to great.

 

[Spksh]

What about weight, though? Here's the banana again.

Replica printed in PETG, slightly heavier.

And then ASA (a kissing cousin of ABS) coming in for the win.

 

[Spksh]

And here we are. They're only just slightly more rigid than the stock parts, and I can now sleep at night knowing that they're actually straight.

 

[Beer_Goggles_RC]

Very nice. The banana had me rolling lol

 

[CertifiedMike]

Since I know nothing about 3D print, prob stupid question here...
Is there such a thing as printing with a thicker nozzel to get a stronger part with fewer passes or will it just turn to a blob on the table?

Great fix for the bars!

I thought the stock ones were ok. I bet when they go by fast, the bends look like they're waving at me!

 

[Spksh]

Very nice. The banana had me rolling lol

Thanks, I try

 

[Spksh]

Since I know nothing about 3D print, prob stupid question here...
Is there such a thing as printing with a thicker nozzel to get a stronger part with fewer passes or will it just turn to a blob on the table?

Great fix for the bars!

I thought the stock ones were ok. I bet when they go by fast, the bends look like they're waving at me!

Yeah, there are a bunch of variables to play with. Some plastics have great layer adhesion (PETG), and some don't (ASA). If you run the nozzle hotter, you can promote better adhesion in some plastics. For ASA, I get the best layer adhesion by running very hot with very thin layers. But layer lines are always going to be relatively weak (compared to injection molded) so it's best to use print orientation to your advantage.

And yeah, the stock ones would probably have acted like some kind of ground-effect aerofoil