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Old 02-17-2012, 10:33 AM   #151
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Originally Posted by BradD View Post
hi guys, just signed up after coming across the forum. Im currently making an RC car for my school project and everything is basically going to made by myself, apart from the motors, servos and the esc.
Was just wondering which motor would be best to use, as i have two. Does it depend on how difficult it is to rotate, the resistance or does this make no difference. I have read about turns and winds and so on, but i only have these two motors and all i can tell the difference between them is the resistance of rotating them.
I have included some pics of the car so far.
Its using an unbranded motor, acoms 2.4ghz transmitter and receiver, Mtroniks Viper oval eco mardave and a sanwa-srm-102 steering servo. Any input or advice would be greatly appreciated
Try both motors. Run whichever is faster.

And get hold of some GRP/Fibreglass sheet, it'll be one million times better than plywood.
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Old 02-17-2012, 11:24 AM   #152
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Here's one of mine. There's the whole series if you look for it.

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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Old 02-17-2012, 08:43 PM   #153
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To be honest, I don't know much about the turn ratings of brushed motors. Everything I run is brushless, so it isn't something I've read up on. Your chassis is unique. I like the fact you used wood to construct it with. Good luck with your car and assignment!
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Old 02-17-2012, 09:06 PM   #154
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Here's one of mine. There's the whole series if you look for it.

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
Nice work Mr. Stormer! It looks like the chassis turned out well for the car, and your choice of parts seem to work well together. What are your plans for paint?
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Old 02-19-2012, 03:49 PM   #155
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To be honest, I don't know much about the turn ratings of brushed motors. Everything I run is brushless, so it isn't something I've read up on. Your chassis is unique. I like the fact you used wood to construct it with. Good luck with your car and assignment!

Thanks and yeah, not sure on the motors but one clicks more solid with the magnets as it turns, like every 1/4 turn the magnets hold it strong, the other is a bit more free turning, not sure if torque is diff or something?
And i plan to make the chassis out of sheet ally, the wood was just for prototyping and testing.
I tried mounting both motors but i think they worked against eachother slightly, bit more rotating resistance/drag and the batteries didn't go for long.

Also, I might have access to two 4.8volt 4cell packs, would this be better then running one 7.2 volt 4 cell?
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Old 02-20-2012, 09:10 PM   #156
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Originally Posted by BradD View Post
Thanks and yeah, not sure on the motors but one clicks more solid with the magnets as it turns, like every 1/4 turn the magnets hold it strong, the other is a bit more free turning, not sure if torque is diff or something?
And i plan to make the chassis out of sheet ally, the wood was just for prototyping and testing.
I tried mounting both motors but i think they worked against eachother slightly, bit more rotating resistance/drag and the batteries didn't go for long.

Also, I might have access to two 4.8volt 4cell packs, would this be better then running one 7.2 volt 4 cell?
With my limited understanding of brushed motors, I think that you're right in that a stronger magnet will result in more torque.

I should have built my chassis mock up out of wood or something easy to work with and not too expensive when I mess it up. I'm on the third version of my chassis now. I actually ordered a sheet of carbon fiber that was 1.5 mm thick, and found it to be rather flimsy and warped from the heat of my hands while I was working with it. Back to alloy.

I had to copy and paste from Battery University.com because I tend to mix up terminology concerning battery connections, but I think this will help you out:
"Battery packs achieve the desired operating voltage by connecting several cells in series, with each cell adding to the total terminal voltage. Parallel connection attains higher capacity for increased current handling, as each cell adds to the total current handling." A series connection is positive to negative, and parallel is positive to positive, negative to negative. Good luck with your car project!

I might as well update this thread with some pics of my HPI Sprint Flux 2 project. The photos didn't load in order, but the first is the roll cage that I brazed together out of aluminum rod that I bent to shape. Very time consuming. The next two pics are of the cage being test fitted around the suspension and driveline. The next is the progression of the chassis, from the original on the left, to version 1 which was quite heavy, to the carbon fiber which was too weak, and to the current chassis I am using. I'll use the carbon as trim pieces like for the dash board and rear self. The last pic shows how I am tying the cage into the suspension with an aluminum plate.
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Old 02-20-2012, 09:23 PM   #157
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Nice work Mr. Stormer! It looks like the chassis turned out well for the car, and your choice of parts seem to work well together. What are your plans for paint?
I'm in the process of making the body flip up with gas cylinders (like hold up the hatch on an old hatchback car). Then, I'll paint it. Car Action wants to review it when it's done. I've been taking my time on it. Its fun.

Probably send the body to one of those guys that does custom painted motorcycle helmets. Kind of the same skillset needed to paint something that isn't "inside out" like lexan.
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Old 02-21-2012, 09:26 AM   #158
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Quote:
Originally Posted by Bob-Stormer View Post
I'm in the process of making the body flip up with gas cylinders (like hold up the hatch on an old hatchback car). Then, I'll paint it. Car Action wants to review it when it's done. I've been taking my time on it. Its fun.

Probably send the body to one of those guys that does custom painted motorcycle helmets. Kind of the same skillset needed to paint something that isn't "inside out" like lexan.
The gas cylinders are a good idea, as I'm sure the body is quite heavy. Please keep us posted as to how it turns out.
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Old 02-21-2012, 10:22 PM   #159
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Gonna be a LONG summer.
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Old 02-28-2012, 04:32 PM   #160
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updating a little on my progress, now all the drive train is basically done.
So the chassis needs to be finished soon so i was thinking whether i should do a full chassis including the parts around the wheels, front back etc like in the photo, or if it would be better to do one small enough with just the space needed for the holes and other structural parts like more common rc cars.

Another question was what sort of gearing should i be running for best performance, currently its just a regular unbranded tin can motor but moves it pretty well and spins up the wheels easily on wood floor and out in the wet.
Also as i made everything from scratch, the front wheels are basically running in little shims which allow the nut to be tightened fully but the wheels still spin, this is shown in the attached image, not sure what you guys normally would do or if you make the parts or buy them instead.

Also, lastly, I'm planning on molding my own body using a mold cut out on a CNC router and a vacuum former. Not sure whether any of the more experienced on here would have any advice on going around this. As i will need to implement my design on our school software and it would be easier if i could get like a side profile and front/back and make it, i dont know.

any input is greatly appreciated
brad
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Old 02-28-2012, 04:54 PM   #161
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I believe you are over thinking the gearing. Being as you're not competing with it, just make it work for the first go round.

then as you bomb it up and down the street, you'll say, "this needs to be faster (or) slower", and you can make an informed decision on how to tune it for your entertainment.
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Old 03-01-2012, 03:42 PM   #162
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along with everything else i said,
has anyone ever tried vac forming using a mold made from styrofoam, like the insulation stuff. I have seen it done and have a machine at school which can cut it out nicely. Just not sure if it will work well or if MDF is a better idea?
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Old 03-01-2012, 05:20 PM   #163
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we use spray foam to make a negative for a carbonfiber fender for our 1:1 dragbike here which we hand laid and vacume processed
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Old 03-08-2012, 11:30 AM   #164
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does anyone have any idea how i can go about designing my body shell on 3d design software. Or is it possible to get the drawings from somewhere else.

Also any ideas on how to make a better setup for the front as they are currently rolling on some brass servo shims which works but isn't great. You can see how it is in the pic below.
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Old 03-21-2012, 11:42 AM   #165
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Do any of you guys still use the older type Nicd and NiMh batteries?
I have a couple, one of which is a Nikko 7.2v 1600mah, it provides a good
bit of power to the motor and works pretty well, but it goes flat within minutes. This is like under 5 minutes after being charged to its max with a 'smart charger'.
Does anyone know what the problem is? or willing to donate an old battery?

Thanks
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