3D Printed PLA Spring CarHaving realised the other day that I’d not used my 3D printer for a few days I decided it was time to take a look at some of the things I’d Liked (favourited) recently on Thingiverse.

Some of the things I’d Liked were RC car chassis, a bit like this 3D Printed RC Truggy we wrote about a while ago.

I used to race RC cars so making one of these would be pretty awesome, but I didn’t feel I was ready for this ambitious project quite yet. As I get more into 3D printing I’m liking the idea of building things from component parts more and more too, but I needed an easier project to start with.

The only things I’d printed in parts and built so far were the Velociraptor Business Card and the RoboSavvy Spool Holder Kit.

Naturally, the 3D printed PLA spring powered car I had found a few weeks ago looked like a great idea. Including my custom made NinjaFlex rubber tyres (more on these later) there were 16 parts to print and assemble. This looks like a fun little project to undertake.

Downloading and 3D Printing the Parts

First of all I downloaded all of the parts from Thingiverse Here, then I set about working out which parts I needed.

The reason I say this is because some parts needed two of them printing (front and rear wheels for example) and other parts had optional modified versions I could use.

An example of modified parts were rear wheels with grooves to fit tyres if required, which as you’ll see later I did use.

I decided on ColorFabb Dutch Orange for all of the moving parts, except for the spring, for which I decided to use RoboSavvy Green. The two sides to the rolling chassis were printed in ColorFabb Blue.

3D Printed Car PartsThere are some instructions on Thingiverse detailing some of the best settings to use for printing. Basically most parts should be printed in PLA plastic, at 0.2mm layer height (medium resolution) and at 10% infill.

The only exceptions are the spring and knob which need to be 100% infill for strength.

After printing the parts on my Glass Build Plate using lots of hairspray, all parts printed perfectly with no warping. Incidentally, I’m loving this glass build plate and hairspray combination, and haven’t used blue tape for months now.

NinjaFlex Black Rubber Tyres

Naturally when I saw the optional modified rear wheels for use with tyres (rubber bands I think) I thought of the NinjaFlex Rubber I hadn’t used for a little while and knew I could do better than boring old rubber bands.

Using Tinkercad and my vernia caliper I quickly took some wheel measurements and designed some custom tyres which would fit snugly onto the back wheels.

I’d seen YouTube videos of this car wheel spinning like crazy on smooth surfaces and I was having none of this, I wanted traction and I wanted my car to be 100% 3D printed.

The tyres printed first time with no dramas. I hadn’t forgotten how tricky NinjaFlex can be to print with, so I slowed down the extrusion to 30 mm/s and all was well. I used plenty of hairspray on the build plate again, even though warping is unlikely with such a flexible material. I was taking no chances.

That was it, for making the parts. I now had 16 parts all lined up and ready to assemble. It was now a little late in the evening though so I decided to leave the assembly until the next day.

Assembling the 3D Printed Spring Powered Car

The Thingiverse instructions on how to build the car included a Trimble Sketchup file showing the assembly, which to be honest I didn’t use. Although I used to use Sketchup a lot it no longer seems to be installed on my laptop.

Never mind, I figured that this thing must be easy enough to assemble from the images and a little common sense. It was easy to work out which parts fitted where, but lots of trimming of parts was required.

Some parts need to fit tightly together and others need to rotate smoothly. It’s simple to work out which are which so I set about putting this car together, with the help of a modelling knife and a little Teflon grease.

The spring (big green spiral) and the pawl (three armed orange wheel) were the trickiest parts to fit together as they were an extremely tight fit and lots of trimming was required. Fitting the wheels onto their respective axles required some trimming and so did the rear axle gear and winding knob.

It did take a little time to trim, grease and assemble but I had no worries as what’s the worst that could happen? Maybe I’d break a part or two, but I was safe in the knowledge that I could print replacement parts if I needed to.

Luckily nothing broke (PLA is surprisingly strong) and it fitted together pretty well.

The tyres were a good tight fit but worked really well. If you print this yourself and want my designs for the tyres feel free to let me know and I’ll make them available.

Just be careful with the modelling knife during assembly and don’t let children assemble this. You’ll be using the knife a lot for trimming so bear that in mind.

First Few Test Runs

The first couple of test runs were a bit shaky, with some adjustments required. The loop on the outside of the spring was too tight on the chassis, which I thought it needed to be.

Originally forgetting that the spring rotates a little, I realised that where the spring attaches to the chassis it needs to rotate a little for the best performance.

Out came the modelling knife and grease and that was solved. The rear wheels also scraped a little on the chassis but moving them out a little on the rear axle solved this too.

I made this YouTube video of my third or fourth run and as you can see it runs pretty well. There’s always room for improvement and I’m very tempted to make some wider dragster style rear wheels and tyres.

Part of the fun is pimping this little car up to the max and that’s what I intend to do. I wonder if I could make a meatier spring too and up the horsepower?

Anyway, please feel free to download this and make it for yourself. It really is fun to do and assembling all the parts and makes a change from the usual process of just downloading and printing a single item.

If you enjoyed reading this it’d be great if you could Like, Share and leave a Comment. Also, download my FREE Beginners Guide to 3D Printing at Home eBook if you’re interested in making cool stuff like this yourself.

Thanks for reading and happy 3D printing.


3D Printed Stumpy Turtle LegStumpy is a 12 year old little cute box turtle, whom due to a serious injury, had to have one of her front legs amputated in September last year.

In the past this would be the end of the line for a turtle such as stumpy.

She would have to find a way to cope with moving around on three legs which needless to say, would have been a great struggle for her.

However, 3D printing technology has proved to be instrumental even in areas you would not have thought possible. In Stumpy’s case, 3D printing was the only hope left for her walking on all fours again rather than having to struggle all her life moving on three limbs.

When Stumpy was first brought before Lesley Mailler, a veterinarian based at the Oatland Island Wildlife Center in Savannah-Georgia, she had a nasty infection in one of her front legs. The infection was so bad that Mailler was left with no other option that to amputate her leg. The surgery nonetheless left Mailler saddened by the unfortunate fate that had befallen Stumpy.

At this point Mailler remembered a photo she had once come across of a turtle with a Lego wheel prosthetic. It struck her that Stumpy could also use one of these to restore her usual life. Now as it so happens, Mailler’s daughter attends May Howard Elementary School in Georgia. What’s interesting was the school owns a 3D printer. As a result, Mailler decided she was going to ask the teachers and school administration to help her build a 3D printed leg for stumpy.

Excited about the whole idea, Mailler explained to the teachers of May Howard Elementary School what she would like them to do for her. There was a team of teachers and students who were ready to take on the project and see it through. Apparently, that is exactly what Stumpy needed – People who could believe in a second chance for her.

5th Graders Help Stumpy

Before kick starting on the project, the teachers at the school chose to select a team of six 5th grade students who would aid in creating the perfect 3D Printed Prosthetic design for Stumpy. The students were chosen basing on their interest and enthusiasm in 3D printing technology and care for the welfare of animals. The teacher heading the project was Reagan Dillon with the six students taking an active part in the project being Matthew Brimblecom, David Rickbroug, Emily Goldstein, Isabel Duke, Jake Gilluly and Kaylee Mailler.

Once the team had been formed Mailler went on to take the box turtle to the school so that all who were working on the project could get the opportunity to meet with Stumpy and visualize the prize they were working towards. This dedicated team of six students plus their teacher worked for 6 weeks purely on coming up with the ideal design that would enable Stumpy to walk normally again.

For them this meant allocating PE time, lunch hours and even putting in lots of after school hours on the project. There are several things that the team had to consider when designing the best prosthetic for Stumpy. First of all, it was of grave importance for the new leg to reach the bottom of Stumpy’s shell. Furthermore the leg had to be of just the required height off the ground to enable stumpy to balance properly on all fours and walk comfortably.

It was equally essential for all of them to keep in mind that the design they settled on should be one that did not interfere in any way with the hinge of Stumpy’s shell. It needed to allow Stumpy perfect mobility in all the possible directions so that even when the turtle retreats back to her shell as is normal, she would not experience any discomfort.

It was clear to the team that for this to be achieved, some trial and error would be inevitable until a befitting design would be reached at. All options that came to mind had to be explored as long as they provided a chance of Stumpy getting her mobility back. For this reason, the six students with the aid of Reagan printed out 15 varying models of the prosthetic wheel. The use of 3DTin Software came in handy when they were creating these designs.

Thereafter, the team looked at all the designs trying to figure out how each of them could be modified to absolute perfection. When they felt certain that they had found the best prosthetic for Stumpy, they quickly rushed to Oatland Veterinary Clinic to inform Mailler of the good news.

Mailler Polishing-up the Design

The first thing Mailler had to do to get Stumpy her new 3D printed prosthetic leg was to remove the stitches she had from the initial surgery. She then fitted the prosthetic to see how it turned out for Stumpy and whether it would really enable her to walk freely again. At first they noted that stumpy could not balance properly meaning that the height of the wheel was not ideal. It appeared too tall, a factor which made Mailler resort to remove the holster of the wheel and attach it directly to Stumpy.

Despite the fact that this appeared to solve the height challenge, there still was one problem left; the caster could not fit against the curved chest of Stumpy as was desired. Using a Dremel tool, the skilled vet sculpted off the plastic from the caster to ensure that it was properly aligned with the shell of the turtle. Mailler then used Gorilla glue to keep the Caster attached to Stumpy’s shell then gave it 10 minutes to dry of.

Immediately that was done with, the moment of truth had come. It was time to place Stumpy on the ground and determine whether all the work that was done for her to obtain the wheeled prosthetic leg was worth it. Well, Stumpy walked with good balance and ease clearly indicating that the project was a success.

More than that, the students and their teacher had learned a lot during this period. To the rest of the world, Stumpy getting her new 3D printed leg was yet more proof of how the technology can positively impact different aspects of our lives and our Natural Environment.

Thanks for reading and please Like and Share this article if you enjoyed reading it.


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