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Help with a custom build large scale RC

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Old 01-16-2009, 11:05 AM
  #1  
studysession
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Default Help with a custom build large scale RC

Hi -

I have a go-cart and think it would be a good project to convert to a large scale RC. I also have a 3 axis CNC Gantry router that I designed and built myself. I will rebuilt a chassis to have this become a 1/4th or 1/5th scale RC.
I think I have a good handle on what I can and can't do with this. The main area where I have questions are servo's and bodies..

What servo's would I need to use for my steering, gas and brake?

When it is all said and done, I will need a 1/4th or 1/5th scale body for it. Where acan I get hold of an inexpensive body for the large scale cars? Money as always is a big factor in anyone's projects, so need help with finding affordable solutions.

Any other advice would also be appreciated.

Thanks -
SS
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Old 01-16-2009, 11:45 AM
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speedy.d
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Default RE: Help with a custom build large scale RC

the ruoter is cool! you should be selling them!
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Old 01-16-2009, 12:27 PM
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Default RE: Help with a custom build large scale RC

Well Studysession,i definately think you should use a custom made servo from a wiper motor especially if you go for 1/4 scale.There is plenty of info on the net and here on rcu how to make one.As for the brake servo,if you use a caliper like mine(i think you need a bigger one),you can modify the spring on the caliper arm to be softer.So that you can use probably a hitec 15kg servo.

Sadly,i have no info on off road bodys.My area of interest in on on roads.

Here is the caliper i'm using:
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Old 01-16-2009, 01:44 PM
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Default RE: Help with a custom build large scale RC


ORIGINAL: Giorgos_cupra

custom made servo from a wiper motor
Do you have any links? When I do a search I get everything but what I am looking for.
Thanks
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Old 01-16-2009, 07:50 PM
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Default RE: Help with a custom build large scale RC

Thanks for the links. Any other help will be appreciated as well. I have two 12v starter motors off lawn tractors I am thinking of using for servos if I can figure all this out.
SS
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Old 01-16-2009, 09:07 PM
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Default RE: Help with a custom build large scale RC

Maybe you could use a windscreen wiper for the steering servo? Ive seen it done before on a project similar to this. You may also want to use one for the throttle and brake depending on how stiff the throttle spring is. You may get away with just a standard 1/4 scale servo though. Anyways, good luck and keep us updated!
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Old 01-17-2009, 10:20 AM
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Default RE: Help with a custom build large scale RC

does it matter if you use a starter motor or a wiper motor to build your servo ? the starter motor will have more torque? coulndnt you use the same type of wiring harness that is used with the wper motor?
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Old 01-17-2009, 10:38 AM
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Default RE: Help with a custom build large scale RC


ORIGINAL: speedy.d

does it matter if you use a starter motor or a wiper motor to build your servo ? the starter motor will have more torque? coulndnt you use the same type of wiring harness that is used with the wper motor?
I am thinking the same thing. Look at the back end of my go-cart. That brake takes a lot of preasure on the cable to actually stop it. The starter motors I have should be more torque and the fact I already have them helps.
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Old 01-17-2009, 10:47 AM
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Default RE: Help with a custom build large scale RC

that the way i seeit if you got it use it. a motor is a motor,right?
do you have any expierence with fiberglass? with practice its not hard to work with just messy and itchy. that bug body that quadracer made is pretty nice have you thought about that?
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Old 01-17-2009, 05:10 PM
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Default RE: Help with a custom build large scale RC

nice project
a starter motor would not be any good for a diy servo.. as its straight drive (too fast )
a wiper motor is comonly used because its a gearhead motor, geared down (slower with heaps of torque)
plus a starter motor can draw up to 90+amps... Far too much lol

use a wiper motor or any other gearhead motor (eg;electric windows motor)
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Old 01-17-2009, 06:06 PM
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Default RE: Help with a custom build large scale RC

that makes semce
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Old 01-17-2009, 07:34 PM
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Default RE: Help with a custom build large scale RC

Just ordered a wiper motor off EBay and have a bid on two others. We will see how it works out.
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Old 01-17-2009, 08:07 PM
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Default RE: Help with a custom build large scale RC

It's really sad, wiper motors are easily half the price of a 333in-oz standard sized servo.

Great tip though, all the torque you need to do some serious actuating.
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Old 01-17-2009, 08:11 PM
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Default RE: Help with a custom build large scale RC

So true -

I have a few robots. I have couple of boxes full of parts and chips. Trying to find my h-bridge's. Should have like two or three I can use for controling the motors. Hopefully I can locate them.
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Old 01-18-2009, 10:04 AM
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Default RE: Help with a custom build large scale RC

A Tone servo is plenty for steering and throttle. More weight= more power or lower gearing or both.[8D]
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Old 01-18-2009, 10:31 AM
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Default RE: Help with a custom build large scale RC


ORIGINAL: bsrman14

A Tone servo is plenty for steering and throttle. More weight= more power or lower gearing or both.[8D]
I already ordered the window wiper motor and have bid on couple more. But for future reference will you post a link to the servo you are talking about?
Thanks
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Old 01-18-2009, 12:40 PM
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Default RE: Help with a custom build large scale RC

That thing is way bigger than 1/4 scale, it's going to be more like 1/3 scale. You need something like this:

http://www.parts123.com/parts123/yb....539.00~~~~~~~F

http://www.metropartsmarket.com/cata...tomgokart.html


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Old 01-18-2009, 01:06 PM
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Default RE: Help with a custom build large scale RC

I like those websites. Thanks for the links. I am going to make a new frame etc... Scale it down a bit just use all the hardware and engine from the go-cart. Or maybe I should go a bit bigger? Dunno....
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Old 01-18-2009, 04:39 PM
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Default RE: Help with a custom build large scale RC

I like the scale of an actual fiberglass bodied go cart like yours. It's huge compared to 1/4 scale it's more like 1/2 scale. Just make sure you have bullet proof steering and redundant failsafes.

http://www.lightninglight.com/index.shtml

http://jo-info.blogspot.com/2008/07/...rt-bodies.html

http://fiberglassgokartbodies.com/products.html

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Old 01-19-2009, 06:43 AM
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Default RE: Help with a custom build large scale RC

Agreed with nitrovette
just over engineer it and you know the chances of a stuff up are greatly reduced.
Aussies & Kiwis do this cos they couldn't be bothered fixing something after they have made it
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Old 01-19-2009, 10:35 AM
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Default RE: Help with a custom build large scale RC


ORIGINAL: bsrman14

A Tone servo is plenty for steering and throttle. More weight= more power or lower gearing or both.[8D]
That's a true statement!!!
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Old 01-19-2009, 10:58 AM
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Default RE: Help with a custom build large scale RC

Scale it up, use a 200+CC motorcyle engine and just drive it instead of remotely controlling it from the sidelines. Something of that size could do some serious damage if it ever decided to run away...
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Old 01-19-2009, 11:10 AM
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Default RE: Help with a custom build large scale RC


ORIGINAL: motionmachine

Scale it up, use a 200+CC motorcyle engine and just drive it instead of remotely controlling it from the sidelines. Something of that size could do some serious damage if it ever decided to run away...

It will be scaled down quit a bit. Going for 1/4 or 1/5 scale. Just going to use the engine, brakes and drive train from the go-cart. Got it for $100 dollars - figure it was worth to mess around with it. My girls friends daughter and I ran it around her grand-moms yard last summer. Had a blast. Now going to convert it over.
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Old 01-19-2009, 03:57 PM
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Default RE: Help with a custom build large scale RC

Hey study Don't know if you found a link for the tone servo's but here it is [link]http://www.vantec.com/ssps050.htm[/link] As said earlier definetly plan on redundant failsafes. Sounds like a good plan. As far as bodies there are quite a few out there but you are looking at 1-200 hundred. [link]http://www.wcm-corp.com/bodies.htm[/link] or [link]http://www.oversizerc.com/c/179568/1/15-scale-body-shells.html[/link] I have never used these merchants so I will say beware.

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