Does 3D Printing RC Car Parts Make Sense?

Hi guys,

The topic for today is a question:  Does 3D Printing RC Car Parts Make Sense?

Everyone who has an old car that's hard to find parts for or has ever had to pay way too much for a trivial RC car part asks this question.  The answer is that it depends.  That obviously leads to another question - depends on what?

Let's begin with an example:  My most recent surprise is the durability of the rear suspension parts I made for the Kyosho Fazer MK2.  They have held up really well.  Well enough that I consider them a huge success.  That said, the shock tower I made for the Fazer was a miserable failure.  You'll break it for sure and probably on the first time out.  So there you go, a success and a failure on the same car.  Even worse, I guarantee that some guy will print them because I said this and the dang things will break much too easily.  3D printing is like that.  It's very hard to get consistent results.  I might print the same parts again but with a different roll of plastic and they could easily suck, or be better.  That's reality, guys.

So what questions should you ask yourself to decide if you should 3D print RC car parts?  Here are a few:

Do you have a 3D printer?

If not, the answer is probably no.  Why?  Paying someone to print stuff for you costs quite a bit even if that somebody isn't making much money.  Why?  It's more hassle than you think and people don't work for free.

If you're buying a 3D printer just to print a few parts it's going to take quite a while to pay for itself.  Not that it won't, but it will take a while.  Really though, the main thing is the hassle, unless you love the 3D printing.  It takes some effort to get a handle on all the factors that come into play when printing.  Nozzle temp, build surface adhesion, cooling, layers, walls, infill, supports and a dozen other variables all come into play.  Then your roll of plastic runs out, you put on a new one, and it's like you're starting all over again because even though it's the same type (or even type and brand), your prints suddenly turn out terrible.  It's an adventure.

Some smarty pants is probably thinking thoughts like, "buy a real printer" or "buy quality filament" or "you don't know what your doing".  There's some truth in each of those criticisms, but if you watch some YouTube videos on 3D printing you'll hear a lot of talk about troubleshooting and beating common problems.  Seems like I'm not the only one who doesn't think it's auto-magic.

So the REAL Question is, Do You Like DIY?

Yes, it's not easy to get good results 3D printing parts, but you can learn from other people's mistakes.  The real question is whether or not you even want to learn.  I can't answer that for you but I can tell you that for a certain type of person it is very satisfying to make your own stuff, even if you could buy better stuff that was made in China by some poor schmuck in a factory, chained to his work station, living on a dollar a day and all the rice he can eat.

If you like making your own stuff, 3D printing is pretty awesome, but it also parts the clouds and shows you a world full of even more and better ways to make stuff.  If you want to make high performance parts, parting those clouds can be a little bit of a bummer.  You'll notice that it hasn't stopped me yet.

What does the part do?

First, plain and simple, the more impact a part needs to endure, the less likely that 3D printing is a great solution.  That being said, speed is a big factor here.  But sometimes parts surprise you, like my Fazer suspension parts.  But speed kills, baby!

• If your car has a top speed of less than 30km/hr, speed is not your biggest problem.  I've made lots of parts that are tough enough for slower cars in my opinion.  My opinion meaning that I run those parts myself.
• There's also a speed level where plenty of stock parts would break too.  I'd call that 50km/hr+.  If you crash hard at 50km/hr you could break just about any part on your car.  The reason you don't is that cars are well designed and you have to hit things just right to break them.
• Driving skill is the factor nobody wants to hear about.  The worse you crash, the more likely parts are to break, and skill makes crashes less severe.  Noobs will always break more parts than experienced drivers, all other things being equal.  Learn to drive with a slower car and then move up and you will break less parts in the long run.  Especially if you like jumping your car.
• Lack of maintenance is a big factor.  Parts wear out, guys.  Lack of cleaning and repair leads to cascading failures.  There is plenty of argument to be made that it's cheaper to run a car until it's destroyed and buy a completely new one than it is to fix an old one.  It's a tough call.  Cheap 3D printed parts buy you some running time with your old car and lets you save most of your cash for a new car down the road.  How's that sound?

Second, the more mechanical stress that a part has to endure the less likely that 3D printing is a great solution.

• High impact parts are not ideal candidates for 3D printing unless you can live with them breaking again more quickly than if you buy one.  For example, an RPM arm is worth about $9 where I live and you have to buy 2.  They are super tough, but that price is not zero.  I can print arms for about a buck each.  I've been running one for about 2 hrs worth right now, BUT I have refrained from true bashing and mostly just driving the car fast.  The RPM arms are worth it if you love bashing.
• Gears are not at all suitable for 3D printing in my opinion.  I have not seen a reasonably priced printing technology that will make a gear that lasts for a high performance application like an RC car gearbox.  The stresses in an RC gearbox are far too high.  A belt pulley might work fine, I don't know because I haven't run a belt driven car.

Third, some parts are just not suited to being 3D printed.

• Good luck 3D printing a high performance shock.
• Good luck 3D printing a light weight AND durable wheel (you can 3D print a wheel, but it will be heavier and probably weaker than a good plastic wheel).
• Suspension rod ends work if your standards are low.  If you want a nice, articulating, ball end link, the strength and fit are not possible for a 3D print.

Look, there are people who have broken all my rules and gotten things that probably shouldn't be 3D printed to work.  I'm one of those people sometimes.  That doesn't mean it's easy or cheaper. 

So, what can I 3D Print?

Guys, even taking all that negativity into account, there are a lot of parts that you can 3D print.  I try to focus my energy on parts that will not be horribly disappointing.  Filaments like TPU, PP, Nylon and carbon fibre offer a lot of possibilities as long as the price is low enough to justify the effort.

Take a look at my projects if you want to get an idea of some parts that I consider highly useful.  There are crawler kits, suspension arms, drive shafts, body mounts, roll cages and other odds and ends.

The one part that has surprised me the most is a 4mm bit holder adapter for a cordless screwdriver.  The first one I ever printed out of PLA is still going strong after hours of use, no exaggeration.  I thought it would be dead after one long screw.  Stick it in a drill and I'm sure it will die instantly, but in a cheap cordless screwdriver that I use all the time it works great.  You have to use the right technology for each application if you want to avoid disappointment but it never hurts to take a shot if the risk justifies the reward.

Bottom Line

Where I live in Canada, a Creality Ender 3 can be had, delivered to your door, for about $300 and it will print very nice parts.  A roll of plastic will cost you about $35 as of May 2021.  It'll take you a few hours to assemble the printer and get it running.  Figure it will take you another 20 hours of actual effort to get the hang of the 3D printing basics, which will be spread out over at least days and probably weeks.  Still interested?

Then, if you want to design your own parts you need to learn about drafting and CAD software.  Not the hardest things to learn, but it does take time.

I've studies engineering, worked in electronics manufacturing, programmed everything that walks or crawls at one time or another, and it took me a while to get good at 3D printing RC car parts.  I have very little idea how that translates to somebody with a different base of experience.  The odds are pretty good that some of my experience got in my way at times, like when I expected different results from tweaking settings.  Other times it helped, like when assembling and maintaining the printer or orienting parts so they are more likely to print successfully.  There are so many resources available to help you that I KNOW you do not need experience if you are willing to put in the time to learn.

So, do - YOU - WANT - to 3D print stuff?  If so, there really isn't anything stopping you.

Wrench to drive or drive to wrench?