Designing a NinjaFlex Bumper for the OpenRC F1 Car

by Jason King on March 9, 2016

OpenRC F1 Bumper FittedAs I’m sure you’re aware by now, the 3D printed OpenRC Formula 1 car designed by Daniel Noree is pretty awesome.

When I committed to building this car myself I did say I’d also try to make a few tweaks/modifications to it, once it was up and running.

It’s certainly up and running now, as you’ll know if you’ve been following my progress and watching the YouTube videos of it in action.

I’ve already made some modifications, like fitting Vehicle Stability Control and designing and making a bracket to fit my HD FlipCam to it for some in-car video.

However, it’s very well designed, so finding potential improvements is a tricky business. That’s what made me take a slightly different approach to making new parts.

Finding a Problem to Solve

In order to make some kind of contribution to the OpenRC project, other than documenting my progress as I build, test and tweak it, I decided to find out what problems I had with the car that others have faced too.

One of the problems is grip and stability, which I and a few others managed to partially solve with Softer Tyres and Stability Control.

This worked just great, but I’ve been neglecting my Favourite CAD Tool OpenSCAD recently, and needed to get my CAD design fix somehow by designing something new and hopefully useful.

OpenRC F1 Spoiler BrokenAnother problem that I and many other OpenRC F1 car owners face is that the front spoiler (which looks amazing and does seem to provide downforce too) is a bit brittle for use on the open road, where there’s obstacles and bad drivers like myself.

The front spoiler tends to break a lot. I think I’m on about my 5th now and some people I know are on their 9th. So, I figured this was a problem which was worth trying to solve.

Some people have created slightly stronger versions of the original spoiler, but if you hit the kerb it’s still likely to break.

I think this problem is beyond using stronger materials and more supports, so what’s needed is a redesigned training bumper, made of NinjaFlex or some other flexible material to absorb impact. The goal of this re-design is to provide protection to the car whilst training and testing, without the need to regularly 3D Print New Front Spoilers.

It doesn’t need to be pretty, just functional and when your mates visit you to take a look at your new Formula 1 car you can always pop the more elegant looking original front spoiler back on to show them.

Designing a NinjaFlex Front Bumper

Having given this new bumper a little thought I knew what it would look like, but without testing, at this point I wouldn’t know if it would ever work or even stay on the car at all.

OpenRC F1 Bumper OpenSCADThe nose of the F1 car would now look like a hammerhead shark, hence the reason I have called this the “Hammerhead Training Bumper”.

It was now time to open up OpenSCAD, dig out my Vernia Calliper and start measuring/designing. You can see my design in the picture of the bumper exported from OpenSCAD. It didn’t take many iterations of this design before I was happy with it and ready to test it.

Although OpenSCAD has it’s limitations, if used properly it’s very easy to tweak a design by just changing a couple of parameters. After the first prototype, I tried it, re-measured a few bits and tweaked a few dimensions in the design.

This resulted in the second prototype being near perfect. As expected, the bumper didn’t look elegant, but it looked functional and did indeed look like a hammer head shark, but without the teeth.

Testing the New F1 Car Bumper

The new bumper fits onto the car exactly as the original front spoiler does, but the part that fits into the original nose cone is slightly bigger so it fits in tighter.

Open RC F1 BumperIt’s made from NinjaFlex so will fit in snugly, but if you decide to make it from PLA or some other less flexible material you may need to trim those bits a little after 3D printing.

Also, if you have any SemiFlex filament then this might work even better than NinjaFlex. I only have a small sample but may well use it for this bumper.

When fitting the bumper you obviously cannot tighten the screw up too much as the bumper will just flex, but during testing (continually crashing the car) the bumper held on really well and the screw didn’t even loosen, probably due to the tension on it from the Ninjaflex.

Here’s a YouTube video of it in action, continually battering my skirting board at home from different angles…

What you’ll notice about the new bumper is that it bounces well, showing that it absorbs a lot of the impact from these crashes. It’s also skirting board friendly, making it more practical to use indoors.

In some cases during testing (and you’ll see from the video) I hit the skirting board so hard the lid of the car popped out at the back, but there was still no damage to the car, or the skirting board.

Another good thing about this bumper is that not everyone uses NinjaFlex, but OpenRC car owners are very likely to have some spare, as we use this stuff for 3D Printing OpenRC Tyres.

Obtaining the F1 Bumper STL File

If you want to try this bumper for yourself, I’ve uploaded the design to Thingiverse here: Hammerhead OpenRC F1 Bumper.

I made mine using NinjaFlex at only 10% infill and it worked just great, but I think I’ll try one at a much higher infill density, especially for use outside where the environment is rougher and the cars speed will be higher.

This could be a really good application to test the sample of SemiFlex I have, which has a flexibility of somewhere between NinjaFlex and PLA, so might be perfect for this. If you have any SemiFlex yourself then please try this and let me know how it goes.

Anyway, I hope this has inspired you to undertake this OpenRC F1 car build, or at least to use your 3D printer to Design, Invent and Solve Problems that would be difficult to solve any other way.

To follow my progress with this project, please visit my dedicated OpenRC Formula 1 Car Web Page and join my 3D Printing Facebook Group where we discuss this and many other 3D printing projects.

Thanks for reading and as ever, thanks to Daniel Noree for designing this car and making it freely available for us all to enjoy.

Feel free to Like and Share this article if you found it interesting.

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