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Old 03-12-2014, 12:04 PM   #1
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Hey guys, my name is Tyler and I just joined the forum. I am an engineering student at Virginia Tech and I am practically designing an RC car from the ground up. Obviously, I won't be designing the motor/servo so I need some advice from you guys. I really don't know a whole lot about this stuff. I want this to be a car 1/10th scale for the road. I want it to be pretty fast. This is what I am thinking so far...

A 4.5T KV Rating geared around 11.0:1.

I am having difficulties in what servo I want to purchase or what is good. I appreciate any advice you guys have to give whether it is in the setup or anything else, and look forward to learning!

P.S. I do have a budget so I am not looking to spend a ton.
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Old 03-12-2014, 12:46 PM   #2
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Originally Posted by tyler94 View Post
Hey guys, my name is Tyler and I just joined the forum. I am an engineering student at Virginia Tech and I am practically designing an RC car from the ground up. Obviously, I won't be designing the motor/servo so I need some advice from you guys. I really don't know a whole lot about this stuff. I want this to be a car 1/10th scale for the road. I want it to be pretty fast. This is what I am thinking so far...

A 4.5T KV Rating geared around 11.0:1.

I am having difficulties in what servo I want to purchase or what is good. I appreciate any advice you guys have to give whether it is in the setup or anything else, and look forward to learning!

P.S. I do have a budget so I am not looking to spend a ton.

Hi Tyler, engineering student here at U Wisconsin-Madison. I have often thought about doing something similar it sounds to what you're doing. I have access to a mill/lathe and can make carbon fiber, so it sounds like a great idea! I would just need to locate plastics... Or use some manufacturers. But definitely sounds like a cool project! Keep us updated with pics if you can.

As for a servo, it can depend on how you have your car layed out. There are good low profile and standard size servos, depending on how much space you have. A good servo will be about $50-60 new. Some brands I would recommend would be savox and Protek. I have used both, and they are very reliable, and extremely fast. The savox 1251 or 1252 low profile servos are very nice, and I run the 1252 in my tc. Protek makes very similar servos in performance for a little less, but don't offer the low profile option. I run the 100ss in my buggy and love it. Just try and find something with .09sec speed or less and you should be good. There are many great brands out there and everyone has a preference. Check out the for sale section for some good deals price wise.
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Old 03-12-2014, 01:10 PM   #3
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Since you have a budget, and this is an educational project so we have to consider the possibility that it may never actually be a good car, I'd probably suggest heading over to HobbyKing / HobbyPartz and getting yourself a cheap low-profile touring car servo for $20-25. You can pick up a cheap gens ace or turnigy battery while you're there.

I would also not suggest a 4.5T motor. It will be far, far too easy to destroy a ton of hard work in a matter of seconds, and there's no way you'd be able to demonstrate it in a classroom / lab if you needed to. In order to keep costs and speeds down, I'd suggest a Tamiya Silver can motor and whatever cheap brushed ESC you can get your hand (Tekin RS might be a good choice if you can find one used for ~$50, because it'll do brushless, too).

There's quite a few interesting threads of custom car builds in this forum if you're looking for inspiration.

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Old 03-12-2014, 02:37 PM   #4
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with very little experience in actual rc cars, designing one from scratch might not be the right project.
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Old 03-13-2014, 02:12 AM   #5
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Having built a few drag cars from absolute scratch ( i mean everything except wheels and gears and the dodgy 2ch radio) when i was a kid i can tell you its lots of work. You can buy a better one for $100 is the reality of it. What are you trying to acheive? What are you being graded on? Do you have to make everything or just the chassis maybe?
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Old 03-13-2014, 06:39 AM   #6
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Will it be 4WD or 2WD? Shaft or belt? Battery layout, the list goes on...
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Old 03-13-2014, 07:01 AM   #7
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Before anyone can really recomend what to use we need to understand what your design brief is.
You are building an RC car from the ground up fine but what do you need it to do. Does it simply need to be able to move around to do a lap or two of the lab or are you intending to race it. If racing is your intention then my advice would be forget it you will only be buying into a load of grief and you will not win. If however the idea is to prove that you can design and build the do not get too hung up on high line motors and speedos buy basic and put your money into making it look professional at the end of the day a basic radio, motor, speedo and servo will get the thing working and able to move and demonstate it is capable of tracking straight turning left and right ect.

Keith
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Old 03-13-2014, 07:06 AM   #8
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Before anyone can really recomend what to use we need to understand what your design brief is.
You are building an RC car from the ground up fine but what do you need it to do.
^ This. We need more details.
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Old 03-15-2014, 02:56 PM   #9
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Thanks for the input guys. and I want this car to be able to drive around on the street. That's the main goal. I guess what I am being graded on is basically just having a functional car. But I don't want to be "good enough" if you guys can understand that. I am pretty sure I want two wheel drive car with a shaft system. I have access to a CNC machine, lathe, mill, and possibly a 3-D Printer. All I have to do is do the design in Inventor or SolidWorks and the rest will be relatively easy.
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Old 03-15-2014, 05:42 PM   #10
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Having built a few drag cars from absolute scratch ( i mean everything except wheels and gears and the dodgy 2ch radio) when i was a kid i can tell you its lots of work. You can buy a better one for $100 is the reality of it. What are you trying to acheive? What are you being graded on? Do you have to make everything or just the chassis maybe?
I think what I am going to design is the chassis, and possibly the suspension system. Obviously I will probably buy shocks/springs.
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Old 03-15-2014, 06:45 PM   #11
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There must be some marking criteria for the unit you are doing. If you are doing a materials unit then focus on the chassis deisgn and optimise stiffness or some such. Dont forget drag cars dont have suspension, you could optimise for low weight and aero properties. If it is showing off with solidworks or some FEA analysis then get the suspension of a cheapo TC or second hand one and then design the project around that. Maybe design some slick body for the car??. From experience both from doing my engineering degree and building cars from scratch I can only advise to keep the building scope to the absolute minimum, you have enough work documenting the assignment.
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Old 03-15-2014, 07:33 PM   #12
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There must be some marking criteria for the unit you are doing. If you are doing a materials unit then focus on the chassis deisgn and optimise stiffness or some such. Dont forget drag cars dont have suspension, you could optimise for low weight and aero properties. If it is showing off with solidworks or some FEA analysis then get the suspension of a cheapo TC or second hand one and then design the project around that. Maybe design some slick body for the car??. From experience both from doing my engineering degree and building cars from scratch I can only advise to keep the building scope to the absolute minimum, you have enough work documenting the assignment.
Originally, the project for the class was to go out and buy an RC car and program it to be able to travel on its own via sensors. Or have an RC car travel a programmed distance and then take a picture of something. I thought that was pretty boring so I approached my professor and asked if he would approve of me designing and then building a fully functional RC Car. This is just a general engineering course.
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Old 03-16-2014, 12:45 AM   #13
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I would suggest you use a cheap standard servo about $25, silver can motor $15 and cheap brushed speed controller $35. Rough prices.

Head to your local track and pick up some second hand springs and shocks.

You could probably pick up a second hand good condition lipo as well.
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Old 03-16-2014, 01:34 AM   #14
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Designing rc cars is really not that big a deal for an engineering student im sure, or a car enthusiest in general. complex things like suspension geometries really are just trial and error. lots of it to get where the sport is now.

I would suggest picking up a used rc car from the classifieds that comes with much of the electronics you need. servo, motor., esc, battery ect ect.
this will give a good idea of where the cars stand right now and you will have physical specimens to work with in your designs.

most of the design of these cars is pretty fricken basic and doesnt require a lot complex machining but fitting all the guts and adhereing to certain specs can be quite difficult. there are very good reasons for the cars of today to look like they do.
as for making parts.. id stay away from machining complex hardware like axles or the like. there are plenty of cheaply available options from various asian makes that would suit your needs very well.

I have given thought to resurrecting my project of a more lipo friendly E4 but to do it, id probably use a lot of spec R parts to make things a million billion times easier. just making my own parts to play around with arrangment of equipment ect ect.

I wish you luck with your project and hope it is rewarding. lots of people around here who modify things and make things =)
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Old 03-16-2014, 04:53 AM   #15
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...... All I have to do is do the design in Inventor or SolidWorks and the rest will be relatively easy.
I'm a 20 year machinist, those words coming from a young, aspiring engineer make me cringe a little.

Youtube/Google some 1/12th scale designs. That's all you need. A bunch of suspension stuff is only going to add complication. Keep it simple and do what you do well. Good luck
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