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thestug
2011.08.26, 02:32 PM
Is it possible to make a small small scale drift car that uses a mini-z board? I have a spare board and was wondering if you can replace the stock servo motor with a much smaller one and run a much smaller drive motor.(both about .5cm around and about 1.5cm long) Also what voltage range is safe to run a mini-z board? I am seaching now for a way to power the car, any ideas. The goal is to make a fully proportional, 4WD tabletop drifter. Hopefully someone has experience building very small scale cars.

color01
2011.08.26, 04:29 PM
Yes, but expect most aftermarket micro servos to suck, except for the really high-end ones ($50 a pop). For drifting, proper servo control is oh so helpful and the Mini-Z servo really takes the cake.

The ASF boards are safe to run anywhere from 3.6 to 6.6V. 7.2V LiPo is usable but I think some people have issues at that voltage -- i.e. you can, but it's outside the range of reliability.

What scale are you looking for? Below 1/32 scale you will have to machine your own drivetrain parts because nobody makes an AWD that small.

thestug
2011.08.27, 12:35 PM
I was looking to make it small enough scale to drift on a regular sized table top. Probabley smalller than dNano size, if possible.

I don't really know much about servos about servos. I thought just changing the the servo motor on the board to something sized more appropriately for a super small scale would work as long as I can still use the same mini-z servo gearing from an AWD. Just imagine a servo assembly modified to fit a much smaller servo motor motor.

Are the voltages for an AWD AM board the same as the ASF?

I was thinking of using an extended micro-sizer/ bit-charg chassis. And modifiying it for 4WD without using diffs so all 4 wheels spin at the same speed for simplicity's sake.

Thanks for trying to help with this because I thought I was crazy for even wanting to attempt this.

color01
2011.08.27, 01:28 PM
Let me not mince words here -- yeah, you're crazy. AWD smaller than a dNano is going to take some creative thinking on your part to fabricate a drivetrain from scratch, and it's also going to be nigh impossible to drive due to the short wheelbase.

The Bit chassis is definitely not suitable for a project like this, due to its steering mechanism up front (big electromagnets, if I remember right). You would be having a lot of fun hacking the chassis for driveshaft space, not to mention keeping the front wheels powered and steerable would be difficult. For front "universal joints" I would look into using a soft, flexible rod material rather than actual joints.

The Mini-Z servo assembly, sans motor, takes up about half the available chassis space in a dNano-sized vehicle-- needless to say that's not going to work, you'll have to find something tiny. Might as well use the dNano servo if you can get it to fit.

My personal opinion is that you should stick to 1/43 or larger. If you want quality parts to go into this thing, and NOT have it cost more than someone else's entire Autoscale collection, then 1) stick to a size that doesn't require micromachining and 2) seriously, have fun designing the drivetrain. :eek:

thestug
2011.08.27, 05:35 PM
Let me not mince words here -- yeah, you're crazy. AWD smaller than a dNano is going to take some creative thinking on your part to fabricate a drivetrain from scratch, and it's also going to be nigh impossible to drive due to the short wheelbase.

The Bit chassis is definitely not suitable for a project like this, due to its steering mechanism up front (big electromagnets, if I remember right). You would be having a lot of fun hacking the chassis for driveshaft space, not to mention keeping the front wheels powered and steerable would be difficult. For front "universal joints" I would look into using a soft, flexible rod material rather than actual joints.

The Mini-Z servo assembly, sans motor, takes up about half the available chassis space in a dNano-sized vehicle-- needless to say that's not going to work, you'll have to find something tiny. Might as well use the dNano servo if you can get it to fit.

My personal opinion is that you should stick to 1/43 or larger. If you want quality parts to go into this thing, and NOT have it cost more than someone else's entire Autoscale collection, then 1) stick to a size that doesn't require micromachining and 2) seriously, have fun designing the drivetrain. :eek:

I was looking for a challenge. I might have to start on this when I get time.

The chassis was going to be about 2x longer than a standard microsizer/bit-charg. So the wheel base wont be super short. I used to "drift" microsizers with just FWD, back, and L/R. So fully proportions AWD should be cake.

I planned to drill the knuckles to accept some sort of universal shaft through it. (I like your idea about a flexible rod material for the joints). Could you avoid using a drive shaft by using a belt drive between axles or just by using two motors(one to drive the front axle and one for the rear)?

AS far as suspension is concered I don't think there will be any just to keep things simple.

What kind of small scale bodies do they make? I guess I should start with that and build a chassis to fit it?

color01
2011.08.27, 05:43 PM
2x longer than a Bit is essentially a dNano. :p Two motors is your easiest way to go about it, you could actually try starting from a dNano, drilling the knuckles as you mentioned, and then fabricating a front axle, and two flexible "u-joint" replacements that then bolt to the wheels. Then just secure the motor to the front of the chassis and there you go, a twin-motor AWD dNano. :) You bring up an interesting point though, I typically don't think in terms of twin-motor anymore because of racing. :o

*Shrug* good luck have fun, once you've figured out the path you want to take, if you need any help implementing your basic design just give me a shout. :)

thestug
2011.08.27, 06:03 PM
2x longer than a Bit is essentially a dNano. :p Two motors is your easiest way to go about it, you could actually try starting from a dNano, drilling the knuckles as you mentioned, and then fabricating a front axle, and two flexible "u-joint" replacements that then bolt to the wheels. Then just secure the motor to the front of the chassis and there you go, a twin-motor AWD dNano. :) You bring up an interesting point though, I typically don't think in terms of twin-motor anymore because of racing. :o

*Shrug* good luck have fun, once you've figured out the path you want to take, if you need any help implementing your basic design just give me a shout. :)

I didn't realize how small dNanos actually are. lol. What would you reccomend for a battery. i don't want to use anything that is round because they would be very space inneficient. I am struggling to find something that Is small rechargable and the right voltage. Microsizers are around 2V if I remenber right. Thanks for the quick replies.

color01
2011.08.27, 06:58 PM
Single cell LiPo is most excellent -- any cheap Chinese charger can deal with them and you can get them in almost any size you want. I pick www.batteryspace.com for these weird-size cells, the quality isn't going to be as good as, say, the Kyosho LiFe pack, but you can get pretty much whatever size you want in a flat pack that you can just put at the bottom of the chassis.

njd13
2011.08.28, 07:40 PM
Awd Dnano has been done:

http://m747.photobucket.com/albums/dan_castillo88/kyosho%20dnano%20AWD/?src=www

Unfortunately, I don't have more info.

deloreanaka8
2011.08.29, 01:25 AM
Since sometimes I also have this kind of crazy impossible ideas, I'm also willing to give you a little hint.
It's actually very easy to build a diff, the biggest issue you'll find is where can you get a propper diff case... and that you'll have to make it from scratch.
If you're doing the whole drivetrain like you said, try using slotcar parts.
I've been looking at my little collection of HO scale chassis and they all use quite small gears, small enough to make a diff for... let's say... around 1/43 scale or a bit smaller, but not much.
Take a look at the gears in this one:
http://slotcarcollectibles2.homestead.com/files/Tomy_SuperGplus_chassis1.JPG

That sprocket is around 1cm, the pinnion I believe it's no bigger than 4mm.

Hope you're able to reach success in your project, does look fun to me. ;)

thestug
2011.08.29, 01:28 PM
Thanks for all the help. I think I am going to keep the axles solid(at least in the rear), because it will be a drift car. Will the car still drift well if I use a spool in the front also? Thanks again for all the help, guys!

tastetickles
2011.08.30, 12:35 AM
Don't bother with a front spool, the car will struggle to do tight hairpin drift coz the drift arc will be very wide. Play with a very loose front ball diff, it can simulate the one-way effect

Eman
2011.08.30, 09:25 AM
I use the stock diffs with gears removed and the output shafts glued in. Spools and ball diffs are fine but they do weigh/cost more. Keep it simple, lock the stock diffs and have fun. The best advice would be to practice.

thestug
2011.08.30, 09:58 AM
I use the stock diffs with gears removed and the output shafts glued in. Spools and ball diffs are fine but they do weigh/cost more. Keep it simple, lock the stock diffs and have fun. The best advice would be to practice.

Locked axles should be light weight IMO. Its just a shaft with a gear on it. How could it get any simpler. Mini-z diffs would be too big in this situation.

thestug
2011.08.30, 10:04 AM
Single cell LiPo is most excellent -- any cheap Chinese charger can deal with them and you can get them in almost any size you want. I pick www.batteryspace.com for these weird-size cells, the quality isn't going to be as good as, say, the Kyosho LiFe pack, but you can get pretty much whatever size you want in a flat pack that you can just put at the bottom of the chassis.

I found some batteries. They are lipo 2S 7.4v 10C. I think the board will be able to handle 7.4, but couldn't the tiny motor/s be fried by passing 7.4 volt through them?

Here is a link to the battery.
http://www.hobbyking.com/hobbyking/store/__10915__Turnigy_138mAh_2S_10C_.html

color01
2011.08.30, 01:56 PM
You definitely won't need 7.2V LiPo for a drifter. If you like the size of that pack, then swap the wire configuration to make it a 3.6V pack with two cells in parallel. Much safer for the board and motor. :)

thestug
2011.08.31, 09:44 AM
You definitely won't need 7.2V LiPo for a drifter. If you like the size of that pack, then swap the wire configuration to make it a 3.6V pack with two cells in parallel. Much safer for the board and motor. :)

I don't think there is a low voltage cut off on these batteries. Couldn't it damage the board by running such a low voltage? I think earlier you said that the boards can handle 3.6v 6.6 to about 7.4 as extremes.

Another question I thought of is what does the potentiometer actually do? I know it has to do with steering.

color01
2011.08.31, 05:01 PM
Low voltage ain't gonna damage nothin'. The dNanos run on a single LiPo cell. ;)

thestug
2011.08.31, 10:12 PM
Low voltage ain't gonna damage nothin'. The dNanos run on a single LiPo cell. ;)

Thanks, but what purpose does the pot serve?

Bodom
2011.09.01, 01:34 AM
Thanks, but what purpose does the pot serve?

Steering feedback. It serves the need of the board to know where exactly the servo is positioned at every moment so it can adjust the position using the servo motor.

thestug
2011.09.01, 11:23 AM
Steering feedback. It serves the need of the board to know where exactly the servo is positioned at every moment so it can adjust the position using the servo motor.

I see. So it is rather important. Can other pots be used in place of the kyosho one? Perhaps there are smaller pots that will do the job?