Sublime865

Alright, I've contemplated this before, thrown ideas around, but its coming to the point where I want to just do it.

I want to build a Radio Control Power Wheels...

I've decided its not just going to be a Power Wheels with some radio gear...

Basically, I want to weld up a box frame, use a solid rear axle and chain drive to an electric motor (a big one. I'm aiming for 20+MPH). All wheels will be replaced with rubber pneumatic, giving me some grip and handling safety. I want to have gas and brake pedals (well, gas and brake), 2 large deep cycle 12v batteries (parallel, run time), dual 1/4 scale high torque servos for steering (with the steering wheel still intact), reinforce the steering mechanism, and in an unrelated note add a small "car" stereo to it as well.


I've narrowed it down significantly, my friends son Trevor, 4, LOVES Lightning McQueen, so the Power Wheels version of that will serve as the starting point. I've always wanted a welder, and to learn to weld, so this will serve as my "training"... I'm familiar with soldering, and I know people who weld enough to know I wont kill myself... I'd like advice on the type of welder to buy/rent/use, I'd like to do a 1 inch box steel frame, and cut out the bottom back of the Power Wheels and drop it on. I forget the name of the part, but I want to have the axle attached by bearings on either side, bolted on to the box frame. There's a part that has a bearing in it, and an outer part shaped like a horse shoe around it, with bolt points on the "top" of the horse shoe, if anyone knows what those are called.... I haven't quite worked out the details of the steering mechanism its self, but I would essentially be attaching something to the steering wheel linkage, and then mounting the servos to that, to turn the wheels and steering wheel. As far as engine goes, that will be mounted transverse high on the box frame, and will be geared by chain, using scavenged bicycle sprockets. As far as wiring and batteries go, whatever I can fit under the hood, wired with nothing smaller than 4 gauge, I'd rather overbuild and I have a boat load of it left over from putting subs in my car. As for radio gear, I've decided on high torque Futaba 1/4 scale servos, Futaba FASST 3 channel radio/receiver, most likely the 6V Power Wheels 7 amp hour battery that we have from some power wheels sitting in the yard, but whatever 6V we have works, with the note of remember this for my ESC question.

Here are my unknowns:

motor to use, I'm looking for something a little bigger than your average 550, I'd like at least 1+ horsepower... Power draw becomes a larger factor at higher power, I'd like atleast 30 minutes of runtime, so I'd go as high as 1.5-2HP. more info: http://www.physicsforums.com/showthread.php?t=198581 Incidentally, does anyone know what kind of power something like a brushed 550 has?

ESC to use, something capable of pushing 130 amps, continuous, which would be a 2HP motor at 12 amps. Also, what can be done to have a 12V ESC run a 6V BEC? Do they make them? That would eliminate the need for a secondary servo/radio battery. ESCs are the one area I am not hugely familiar with, as I am a Nitro guy through and through, this will be my second "real" electric RC, and my first is a box stock unused E-Firestorm (the Nitro Firestorm is so much more fun...). Also, reverse. Important to me, but not a deal breaker for the right ESC. My ideal ESC will handle 130+ amps, have braking, delayed reverse, and a 6V BEC. My minimum requirements are 130 amps, and braking (really don't want to have to wire it myself).

Welder/Welder type, arc welder work? simple and clean, will it weld boxed tube steel? If not, what kind of welder should I be looking at? I'm not looking to spend more than $500-$600 on a welder (if they end up being more, I'll just rent one), its just for basic projects like this one, and few/far between.

Other electrical requirements, I have a 2 farad capacitor, would it be a good idea to use that along with the battery for start up juice? Of course, if I have room.

Braking, is it possible to use a variable resistor to apply both motor terminals to positive to create a variable electronic braking system? Or will the ESC handle that for me? (basically, think of a drill. When you let off the trigger, it stops the rotation immediately. It does so by instantly applying both motor terminals to positive). I was contemplating atleast an e-brake which cuts power and puts both terminals to positive). Again, realllly want the ESC to handle this for me.

Ideas on gearing, I plan to run a 3 gear system, small gear on the motor, large gear on an intermediary spindle, with a second fixed gear, geared 1 to 1 with the axle (for the ground clearance of not having a large cog on the axle its self).


Anyway, supporting mods will be lighting, audio, and whatever cool ideas we come up with for that 3rd channel (maybe the e-brake idea? There will be passengers, wee ones).

I looked at the HPI Baja 5B/5T and the HPI Savage 5T (yes, europe has the 4WD Savage in 5th scale truck form, nitro not gas). I already have the Savage X SS and I'm about 2 grand into it, along with a Nitro MT2 18SS, Nitro Firestorm, and E-Firestorm. I'm not looking to buy one a little bit bigger than my Savage (which has been built to the point where the Savage XL is its little sister). I want to build one, and I want it to be big. Really big. (yes, I contemplated a golf cart, too simple and too expensive). So I'm looking for advice, hopefully going to get this rolling as a winter project. Anything I missed or you think I should know, I'm happy to hear.


Thanks for taking the time to read my long winded post :P

Mudgy

with the steel frame, electric motor and batteries (and possibly a passenger) a 1/4 scale servo won't handle the job of steering. Perhaps a larger type may do?

There's a fellow on youtube made a steering servo from a Makita drill on a 50kg buggy (home made) goes allright, too!

http://www.youtube.com/user/rightoff.../1/2EWBllJn44Q

I think he's from South Australia

Dirty_Vinylpusher

So basically it's going to be both radio controlled AND driveable via pedals?


If you're going to use chain drive I'd recommend going for #25 pitch chain - the same that is used on pocketbikes and mini scooters.
Then you'll get away with 2 chains as well.

cuemando

Bearings like these?

http://www.thebigbearingstore.com/se...200/Categories

Just buy the best MIG you can afford. Stick/arc/MMAW welders are cheap but not as easy to use without a lot of practice. You can pick up an inverter machine with hot start and be able to hook a TIG torch for under $500( without the TIG gear of course, that would be another couple hundred) Better to get the MIG/GMAW. If ya not welding 3/4" plate, $600 will get you welding 1/4" like a pro. Gas is better than flux core. Flux core is messy and the flux goes off after a few months.
Good luck.

Jgilk1

i dont know how to say this with out sounding rude but....

your looking @ a 80# roller fully loaded not including a rider your looking @ an industrial size electric motor and a servo that can exert a lot more force then any thing a 1/4 scale can do....

.... you will have enough power draw off the electric motor/servo i don't think it would even be worth it to install a car radio.... (elcheapo run off its own aa batteries) and for run time you might as well run 3 6 cell deep cycle in parellel (max power or such) like 1200amps cranking power so you shouldnt cause any ammount of power draw to "BURN" a cell


http://www.sportsimportsltd.com/gene...m-battery.html