Building the OpenRC Formula 1 Car Rolling Chassis

by Jason King on January 27, 2016

OpenRC F1 Car Chassis DoneIf you’ve read my Last F1 Project Article you’ll know that up to this point I’ve already 3D printed some of the front steering and suspension parts. I’ve also taken delivery of the nuts, bolts and screws I ordered, along with lots of new PLA plastic from colorFabb.

The natural next step for me now is to 3D print the rest of the rolling chassis (all but the bodywork) so that I can construct something that starts to resemble an F1 car.

It’s at this point that I spent every evening and much of last weekend making more of the chassis parts, including the rear wheel/axle/gear assembly, all from black Floreon PLA.

I’d already largely resolved the warping issue by using rafts, blue painter tape and strategically placed drops of super glue on the raft, so it was just a matter of more slicing and more printing for a few days.

Eventually I’d made most of the rolling chassis parts and was ready to take on the bit I was a little scared of, the front and rear chassis plates.

3D Printing the F1 Chassis Plates

OpenRC F1 Car Chassis PartsMost of the rolling chassis parts have been 3D printed up to now so it was time to take on the main chassis parts, so I could fit all the other parts to them. I was worried about warping with these parts but I had a plan.

I used a raft for the two main chassis parts, blue painter tape and super glue for the raft corners, but I also used colorFabb PLA plastic.

This is stiffer, less prone to warping and was all part of my plan to 3D print these large, square-ish, flat parts first time with No Warping.

One other little trick I use to prevent warping is to move the nozzle a little closer to the build plate than usual, which helps adhesion. During printing such a large flat area this actually made my extruder click. This means that the nozzle was a little too close to the object being 3D printed and the plastic couldn’t be extruded so was slipping in the extruder.

Loosening the build plate adjuster screws a tiny amount during printing reduced then eliminated this. I checked the layer lines and they looked absolutely fine so it looks like I got away with it this time and didn’t have to start again.

Both main parts of the chassis ended up 3D printing really well, so maybe my initial worries were unnecessary. I was also very impressed with Daniels design here, as the two parts clipped together like two jigsaw pieces. When I make the bodywork and bolt it to the chassis, this will provide the real strength, but for now the two chassis pedicels fitted together very nicely.

FastEddie Delivered My Bearings

The time for some real construction was now looming as I had all of the rolling chassis parts 3D printed. The nuts, bolts and screws has already arrived and I was just waiting for the bearings.

I checked the post and there they were, sat waiting for me. They could have been there for a few days for all I know. Anyway, now it was time to put a lot of the OpenRC F1 car together and yes, I was excited.

OpenRC F1 Bearings ScrewsThe downloadable diagrams used to help with construction are pretty clear. Just be careful to use the right screws as there are 8mm, 10mm and 12mm M3 screws, some flat headed and some round, so they do all look quite similar.

I found some of the slots for the M3 nuts were a little tight, but it’s possible that my 3D printer is to blame, or maybe I bought the wrong nuts. I’m not sure but they all fitted in the end with a little trimming and little patience.

The bearings were tight in the front wheels and the rear axle, but to be honest it’s better than them being loose, so be patient, trim where necessary and these will all fit into place eventually.

I thought about dipping the parts in warm (about 60 degrees) water to soften them before slotting in the bearings and nuts but I feared it’d bend and warp out of shape if I did this. It’s something to try if you have real troubles and the worst case scenario is that you’d just have to reprint the part if this goes wrong.

There’s one part that I 3D printed twice in Floreon PLA and I think I’ll reprint again today using colorFabb PLA. That’s the rear axle. I think the two ends have warped very slightly, enough to make the ends thinner so the wheels don’t fit tightly onto them.

I’ll try colorFabb PLA, which I might be able to do with no raft. This’ll give a much more precise shape to the part if I can do it. The wheels fit onto the axle ok, but I think the little bit of slack will only become worse when I fit the electronics and put some horse power though the back wheels.

After reprinting the Axle I’ll report back. I could always open up OpenSCAD for half an hour and design a new one or send the design to Shapeways to make, but I hope I can do this without going to those extremes.

3D Printing the NinjaFlex Tyres

In the past I’ve designed and 3D Printed Tyres in NinjaFlex so although this might part be a little bit scary for some, I was really looking forward to it.

Based on tyres I’d designed and made before I chose the following settings to start:

  • 0.3mm Layer Height – when the tyres are slightly used (scrubbed) you won’t see the layer lines and as NinjaFlex is quite slow to print a higher/slower resolution isn’t necessary.
  • 235 Degrees – this seems quite hot but for me it means good layer adhesion and allows the NinjaFlex to flow well preventing clogging and bending in the extruder.
  • 5% Infill – this is just enough to allow a bit of stability in the tyre and for the top side wall to 3D print without bridging and sagging too much.
  • 30mm/s Speed – slowing down the extrusion speed like this is recommended by Fenner Drives who make NinjaFlex and is vital for me, otherwise the NinjaFlex just bends in the extruder.
  • 10 Shell Thickness – this leads to quite a hard sturdy on road tyre although it might be too much for an off road tyre where more springiness is required.

Open RC F1 Car TyreThese are the settings that work well for me and when I actually test the car on the road these may be subject to change.

Some will say 235 degrees is too hot and that shell thickness of 10 is too much, but these work for me so I’ll go with them for now. The beauty of 3D printing is that it’s easy to experiment.

Using these settings it took about 3 hours to 3D print each tyre. That’s quite a long time but with flexible filament there’s no issue of warping to worry about so no rafts and no supports will be needed.

I wouldn’t be tempted to make more than one tyre on the build plate at a time either, as with NinjaFlex you might see a stringy mess between the two tyres. This is easy to trim when finished but it’s best avoided in the first place.

Where We Go From Here

The rolling chassis 3D printed and fitted together quite well. All nuts, bolts, screws and bearings are in and it does actually roll quite smoothly.

Open RC F1 Car ChassisI’ll try a new rear axle and I may have to use a stiffer material for the Front Upper BOM as the servo save appears a little loose too.

It’s all stuff that I can fix easily and then it’s onto the body shell. I believe there’s about seven large-ish body shell parts to 3D print before the 3D printing stage of this OpenRC F1 car is finished.

As you can see from the pictures, I have already made the rear spoiler as this forms part of the chassis build.

The blue is also the first part of my chosen color scheme (apart from the obvious black for the chassis). In my next blog post I’ll have 3D printed the body shell parts and it’ll be looking like a real Formula 1 car. Watch this space.

If you’re interested in following my progress with this project then my OpenRC F1 Car Page is a good place to follow me, but if you like a little interaction and discussion my new 3D Printing Facebook Group is the place to be.

Thanks for reading and thanks to Daniel Noree for another great OpenRC project design.

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