How I Get Strong 3D Prints – The Skateboard Trucks Experiment

I talk alot about my love & fascination for 3D printing technology. To me 3D printing is freedom of expression, where i can challenge norms and traditions. I can just try things to see what happens without a real purpose, just out of curiosity. Every new project is a chance to learn something new and with that comes progression. I think skateboarding is similar to 3D printing in the way it enables creativity and expression in so many ways and your free to do whatever you want. There’s as many ways to approach this as there are opinions on how to get thethe strongest 3D print possible. In no way is this the ultimate way however, this is a method I use and works well considering the end results over the past years.

Skateboard Trucks

For some reason a friday last year i decided i wanted to make 3D printed skateboard trucks. It´’s kinda similar to when i did the OpenRC Truggy years ago. It’s a application with high demands in terms of durability and nobody thinks you can pull it off, perfect! Don’t get me wrong, i’m not trying to change the world here. As always this is nothing but something i do for fun and as a added bonus learn more about 3D printing, design and maybe even skateboarding. And as per trdition i always underestimate projects before starting and this time was no different.

Something New

I needed to take a break from designing OpenRC stuff and get my mind on something else. So i went to the local sports supermarket and got myself a cheap skateboard. I took the trucks apart and studied the design. For a project like this I always start by trying to imagine where forces are applied in different scenarios. I’m not a skater so i could only imagine what happens when it’s thrown around. It’s easy to just think that printing the “hanger” with the layers perpendicular to the the wheel axles would be the obviously best solution. And that’s exactly what i did at first and considering all the comments posted on the first picture this would be considered the norm. But as i mentioned earlier, sometimes challenging the norm and thinking one step further can be a route to progression. After some tests i realised there are a number of areas that would suffer from this so i decided to try something else. So instead of always thinking in 90 degree rotations, why not go halfway. In the hanger design i needed strong layers going in both 0 and 90 degrees. But as doing one would result in the other parts being to weak why not go somewhere in between. It’s not perfect but it would add some level of strength for the areas that need it. Of course this idea is relying heavily on the 8mm threaded rod going thru the hanger from wheel to wheel. Without it, this idea falls short.

Material

In terms of material i used a carbon fiber infused Nylon which is the strongest material i have that will offer some level of rigidity to the geometry aswell. Nylon is needed for impact strength. Also, to add more strength a larger nozzle is needed to get bigger layers. Here’s were a compromise is needed. Let me explain. Going from 0.2 to 0.3 mm layerheight (layer width needs to change accordingly) won´t change much but if you go from 0.2 to 0.5 or more, that’s when you will see a result in terms of durability. However, it´s not as easy as just changing to bigger nozzle and this is because the bigger the nozzle (and layers) the less precision you get. So a boring compromise is in place here. I didn’t go with the thick strong layers as i wanted but i stopped at 0.35mm layerheight with a 0.6mm nozzle in my ZYYX PRO. Again, this was a weekend project just for fun so i took the easy route this time.

Slicer Settings

Also, to get strong parts it’s extremely important to pay close attention to the infill. Traditionally the infill is mostly about adding internal structural, top layer support and to a limited extent some level of strength. But in this case we need it to be as strong as the rest of the part or all else is at waste. So i usually use a infill pattern that will lay down filament over and over again in the same path like fast honeycomb pattern in Simplify3D as i want as much contact surface between the layers as possible and maximise interlayer adhesion. Choosing something like a rectangular infill will only be a waste of plastic. Next, infill extrusion width. I typically want just as much plastic being layed down just as on the perimiter to create a equally strong layer bondning. When i print something that demands as much strength as possible i actually over extrude the infill slightly to ensure each layer connects propery to the previous layer! If the infill is not optimised for strength we will end up with only the perimiter holding the part together. Taking time to make a strong infill is well worth the work and will ad alot of strength.

Design

So as mentioned above i took measurements from the parts on the skateboard i had bought and made my own design in Fusion 360. One thing i really like with Fusion 360 is the ability to combine parametric design with T-splines (sculpt mode).  It’s really powerful. As i like to always publish a STEP file of the complete assembly for others to play with i added more parts such as the bushings, kingpin, nut and threaded rod. (See link to files below this post).

Fun & Educational

Looking back this was a fun and educational project. It was great fun putting it in the hydraulic press to see what would happen. It´s great to sometimes re-engineer stuff like this, add your own tweaks to it and play around as you will learn alot. Breaking it, going back to the drawing board to redesign and add strength just to go out and do your best to smash it again. Don´t be afraid to try different something different even if people tell you not to. Trying different orientations for printing these trucks was also a great experience to see what will add the best strength. All in all i think it actually came out better than expected and i use the skateboard now and then.

Check out the videos and download the files for the trucks on the Skateboard Trucks download page.