My biggest project yet! Please let me know what you think! I need some opinions on what I should do.
amazing project - you can use nylon (or pet) probably pom would be good but is hard to print. If you calculate the power on those small parts you would end up with metal - maybe if you increase the diameter of those high stressed parts. Also i would worry about cooling the motor however very nice project you have here!
@Ulrich_Baer Thank you! Is PET easier to print than Nylon? I keep hearing about it, but I am afraid if my printer can print stronger filements than PLA or not. I have noticed a loss of power after around 20 minutes of driving out in the summer heat. I assumed it was battery fatigue, but possibly the motor was getting too hot. I will look into that.
@Engineering_Nonsense If you can print PLA, you can almost certainly print PETG (provided you have a heated bed). It’s such a good material I no longer see a reason to use PLA… It’s as easy to print and as good looking (glossy) while not as hard, more flexible and a lot more durable.
Awesome project! Must have taken ages to desingn and prototype. Kudos.
i would say nylon and PET are comparable in printing (nylon is more difficult to get it right) - if you print slow it could work, a bigger nozzle also could help. But maybe think about printing a PLA mold and using epoxy with carbon fiber for those parts. You can also print that “bone” with a void inside and put/glue a thin steel or carbon rod inside to take some torsion strain.
@Petr_Sedlacek I will buy some then! Thanks for the info. And yes, it took months to design and redesign and test and redesign again over and over lol
@Ulrich_Baer Good idea, I’ll look into that. But I should say that I put the clip of the broken axle to illustrate how important proper print settings are, but actually those axles dont break anymore, now that I dialed my settings in for that specific part.
My suggestion is to buy a cheap Traxxas slash or ECX Torment and tune it to perform on a short course track. Doing all the research and testing to make it work in that environment will give you loads of information on RC cars and what changing parts can do. Like the reason your suspension may not be working right can definitely be due to too much friction, it could also be that the shocks are just too stiff for the weight of your car. Just stuff like that. You could also see how the suspension works so you can reduce your own friction. Some parts should be metal though. Like the spot where the shocks mount for example. Having a metal ring that a screw can go through would really reduce the friction.
@Kevin_Danger_Powers You’re right. And yes, that should be metal, but the goal is to maximize both reliability and also maximize the number of parts that can be printed. What I did was put a steel washer between the linkage and the bracket, as you mentioned, this helped, but now I think that there is a perpendicular torque twisting the linkage and causing it to bind on the screw–I think this is where the friction is from.
@Engineering_Nonsense that’s very possible. I guess you just have to balance what parts can really be 3D printed without sacrificing too much performance.
@Kevin_Danger_Powers Exactly
@Petr_Sedlacek petg is cool, but it cant handle hits, it breaks easy when u crash into something. Way better is Nylon, but im still searching for a better material for RC related stuff. Friend of mine is trying to print with a nylon/carbon mix. Hope that stuff works out well.
@N_Y_NakiYozora try PC (polycarbonate) - very impact resistant.
@Ulrich_Baer They make PC for 3D printers?
@N_Y_NakiYozora Interesting. I haven’t had any major breaking issues at all, the biggest thing is just designing the parts in a way that they can handle the forces. But at the same time I am using a 335W motor so that’s a lot less power than some of the other guys.
In my mind (Knowing nothing about RC cars) 350W is more than enough, it has WAY more power than the little wheels can deliver to the ground, the problem is the RPM’s maxing out when the motor meets its max speed. I’ll need to increase the gear ratio.
@Ulrich_Baer yeah, that stuff sounds great, i will give it a try. Thank you✌
@Engineering_Nonsense i use it for quadcopter parts and tinywhoop frames.
so sometimes i have walls with 1-3 mm thickness…not much inner strukture possible. And yes petg is pretty strong but it breaks very easy on fast impacts even with a good inner struktur and a lil bit bigger parts. Do a hammer impact test and u know what i mean😉 i tryed different temps, it dont survive this test. Difference with temps was one broke instant when trying to bend it, the other one i could bend without breaking it.
Oh I see, well good luck!
@Engineering_Nonsense you can get every thermoplastic as a filament - i have it and it also have nice optical properties. Here some posts about it:
https://plus.google.com/+UlrichBaer/posts/43K9S5jpRFM
and
https://plus.google.com/+UlrichBaer/posts/cnkR6Gs72G4
@Engineering_Nonsense the rpm’s of a brushless motor like that correspond with the voltage that the battery is putting out. Along with changing the gear ratio, you can also increase the voltage for more top speed but you’ll also get even MORE torque. Probably the best thing for that car is a higher kv rated motor. Typical RC cars will use around a 3500kv motor. The higher the rating, the more speed and less torque you’ll get.