How to Design a Custom RC Car – Part 1

Introduction

Go to Part 2 How to Choose Motors and ESCs (Speed Controls)
Part 3 The 3D Printer (Tevo Tarantula)

I have decided to create the most thoroughly documented custom RC car project ever! I think that many people have shared my experience of being really interested in some cool tech project but are too intimidated by the lack of documentation of the other cool projects they got their idea from. Or you simply understand several parts of your project but are not sure how to put them together. Or maybe you just don’t know the first steps to take to start your awesome project. Join me as I show you the process that you could take to accomplish a similar project.

I have previously owned a 1/16 Traxxas E-Revo brushless truggy with VXL and brushed motors, a 1/16 Traxxas Rally car VXL and brushed, a 1/10 HPI Savage XS Flux truck, a WLToys L939, a ECX KickFlip and an upgraded 1/8 OFNA Ultra LX2e buggy. Also I had a Tyco Super Rebound when I was a kid. I include that on this list because it was probably the best RC car I have owned so far! It lasted 3 years of abuse without every needing to be repaired. That included driving it off my parents 20 foot roof onto grass multiple times to see how it flew through the air! Sadly I don’t have it anymore but I found a picture below from online to share with you. That car is more or less the inspiration for this project. I have heard over and over again on RC forums that any car that is fast enough to be fun will break eventually/regularly. I want to prove that wrong!Tyco Super Rebound

Before I continue I should point out that designing your own RC car or any product from scratch is not for everyone. If you just want something fun, affordable and don’t need it to last forever then check this out! http://www.rchobbiesoutlet.com/rc-brushless-electric-buggy-car-hsp-1-10-scale-xstr-top2-11-1v-lipo-2-4g-10718/

I have spent a lot of money and about 6 months trying to find the best value, fun RC car. I didn’t find any of my above list that really seemed great. That link above though is as good quality components as I have ever seen on a RTR ready to run car and at a price less than most of them! If you aren’t into tinkering just buy that and have fun. If you love creativity and building stuff then read on…

My Vision for my XFire RC Car

I want to make a 4 motor, 4 ESC (Speed Controller),  no suspension indestructible RC car for general fun, maybe some racing and definitely bashing. This project is partly inspired by my fantastic experience with my Tyco Super Rebound. My end goal is to make it roughly 1/10 scale. Four separately controlled motors will allow me to eliminate the entire classical drive train and differentials that fail so often in regular high end RC cars currently. It will also allow eventually for things like traction control, auto jump landing horizontally (to avoid breaking parts) and improving cornering in ways that wouldn’t be possible with a friction based mechanical differential (friction greater than a factor of 1). With no suspension I will need large tires to take up the abuse that the suspension normally helps with. It should also be symmetric vertically so it can flip over and keep going. I plan to use whatever materials that I can easily access and process myself. I plan on using my Tiko 3D printer to print any complex plastic pieces required once I get it! I don’t want any proprietary or purchased materials unless they are cheap and easy to source. The worst part about RC cars is finding the right replacement part that is affordable! I also plan on upgrading every part that breaks until I have a design that can take similar abuse to my Tyco Super Rebound without breaking for at least a year! If I succeed, maybe I will launch a Kickstarter project so everyone can enjoy an RC car that is actually designed to be used and not break!

The Plan

I plan to break down my project into the following steps. Basically Part 1 will be the funnest cheapest indoor RC car possible and Part 2 will be the funnest cheapest outdoor RC car possible. Each car has an optimal trade off between size and cost. The sweet spot is where the most fun is to be had because stuff generally won’t break and doesn’t cost too much to start with. *Update Part 1 turned out not to be any cheaper than the larger version so I am skipping straight to that for the rest of these posts. See Part 2 How to Choose Motor’s and ESC’s for how I figured that out.

Part 1 – Mini Cheap Version to Get Started
-Take my WLToys L939 and repurpose as many components as possible to save money (receiver, transmitter, wheels, maybe battery, maybe motor, maybe esc…)
-Get the lowest kV tiny motors that I can find so that I have as smooth as possible speed control at low speeds. If that doesn’t seem doable find cheap small motors that have internal gearboxes.
-Analyze the best method of getting power to each motor/speed control. If I can afford it and space allows on the little car, buy ESCs that can also be used for my big car.
-Analyze the best method of controlling each motor – H bridge, motor drivers on chip, 4 speed controls, 2 speed controls (tank driving)
-Choose an adequate Arduino type programmable board
-Estimate the power required to have 4 motors each equivalent to the one in the original L939
-Order cheap electronic components from Amazon, Banggood or Ebay (preferably in that order). This will probably include an Arduino nano, any wiring and connectors, the ESCs and motors…
-Learn how to program the Arduino/ESCs properly.
-Make a simple platform to test the setup.
-Design the parts needed to be printed
-Figure out how to print good parts and modify part design as required
-Print parts, assemble new little car and test!
-Trouble shoot engineering design issues and maybe come up with a whole new design until it is fun and durable

Part 2 – 1/10 Scale Awesome Version
-Estimate power required based on 1.5-2 times as much as my 1/16 VXL Traxxas cars had as their electronics are documented quite nicely online.
-Choose motors, gears, ESCs, batteries, wiring setup and Arduino board based on overall power goal
-Source electronic components
-Apply insight from small version to build large version
-Research, calculate/do FEA analysis on frame ideas and prototype until I come up with an almost indestructible frame either 3D printed or not.

Well, that is the plan. As we all know it probably won’t go like that. That is why this project should be interesting to follow. I will post all the problems and the steps I take to solve them as I go. I will link to source code, places to buy parts, my engineering calculations, part models etc… Hopefully this can start a community like the other openRC  initiatives but the purpose of this design for maximum fun as opposed to just creating an open source standard type of RC car. I plan on posting updates each month. Please post any tips or questions you might have!

Here is an example of someone doing a drift car similar to what I want for my larger scale version.

Thanks for reading. See below for the list of posts I am planning on making or already have.

1 – Introduction to Project XFire (This one)
2 – How to Choose Motors, ESCs and Batteries
3 – The 3D Printer (Tevo Tarantula)

How to Choose a Gear System and Model it with 3D Software
How to Choose, Install and Program an Arduino Controller
How  to Design a RC Car Structure/Frame/Body
Simple Engineering Calcs for Strength
Testing!
Redesigning

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2 thoughts on “How to Design a Custom RC Car – Part 1

  1. Anonymous April 26, 2016 / 2:53 am

    I hope you are still working on this. It sounds amazing!

    Like

    • steventaitinger April 26, 2016 / 3:21 am

      I am! I just got last week the last of my electronics in. I am mostly at a stand still until my 3D printer gets here though as I don’t have any precision metal working equipment. The last Tiko3D update though sounds quite promising. I was also holding out on the 3D modeling post until I finished writing my own program but that doesn’t seem on the books right now. I should probably just do it with OnShape like most people would that are in a similar position as me. I use Creo at work but that isn’t very accessible.

      Like

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