Geared DuraTrax550 motor

[densohax]

I was wondering if I could swap this motor : http://www.motiondynamics.com.au/worm-d ... -180w.html
for this one http://www.robotmarketplace.com/products/0-PDX132.html

And if this is not powerful enough, what could be the reason?

I am in the process of choosing a motor for a 2DOF Simulator and I want something better than a wiper motor..

Thanks a lot

[motiondave]

maybe, if I converted it right, its a 84nm motor. http://www.unitconversion.org/unit_conv ... orque.html
But at 148 amps stall, you'd want a HUGE h-bridge to run it.
efficiency is low at 45%
the motion dynamics are 85% efficiency.
The motion dynamics motors stall at about 30-38 amps to give 20-25nm torque, so a JRK will run it.
Buy it and test and prove us wrong.
Also, refer to Floriskes thread for the ebay alternative of you want cheaper.
Cheers, David.

[x1610]

With that stall current youre small motor will smoke in a fuw seconds.
They dont give backlash,and it will be big probebly.
If you want to go this way look at a gearbox from motioncontrolproducts.uk(they have the cheapest)
And for a nema23 servo(google with skewed rotor servo)
You must pay a lot more to get better motion,but its possible to pay less than SCN5
sorry for my bad englisch

[densohax]

Thanks for all the replies!

Actually, I'm pretty sure they got the 148 amps wrong, I looked at other motors on the site and they always are wrong according to the datasheets of other motors.

I think this would be something like 18-20 amps stall current, for 148 amps the coils would have a resistance of like 0.08 which doesn't make any sense!

Btw, I am designing my own H-Bridges with IRF3710 (100 Volts 57 Amps).
I will probably add current limiting features for the H-Bridge also.. PID loop will be microcontroller side, I'm still thinking about using a parallax propeller 8 cores microcontroller to drive many outputs and gauge.

Anyways, this motor seemed not bad, but it's not beefy, it's a little motor that turns a big gearbox.. So yeah efficiency isn't going to be good, but I'm not sure if it's a real problem in my case..

[densohax]

Actually, the 148 Amps figure might be right after all :
>>
Q: i'm not planning to use the RS-550 as it is, i'm planning to use this PDX16 - 16:1 Gearmotor. Is this still overkill for a hobbyweight?

A: Even more so. The Duratrax 550 motor is more powerful than the BaneBots RS-550 -- about 50% more powerful. Stall current is 148 amps -- rather too much to control with a 12 amp ESC! A pair of these motors will provide more than one horsepower. Massive overkill.
<<

This is a Duratrax 550 motor.

I'll investigate the 148A stall current to see if it indeed kills the motor.

Here is a video for this motor : http://www.youtube.com/watch?feature=pl ... LLQXDcXAKE

The gearbox is the part that cost a lot, the motor is around 8 to 10$. It turns at 22'000 RPM on a 132:1 gearbox.
Near the end of the video, you can hear the nosie it makes, kind'a like an electric screw driver, hard to say if it's going to be too loud, but I guess I could design a muffling box for them.

The shaft of the gearbox needs to be supported by 2 bearings IMO, I would put one on each side of the shaft.
I would also put a minibike disc brake assembly on the shaft to lock the motor in place (electronically), instead of having to give it > 40 amps at stall currents.

Since I'm designing the entire electronics I'm free to control the constraints of the system..

Do you think this is a viable solution?


Edit.: Another limitation :
>>
Maximum torque recommendation
We recommend maximum torque not exceed 35 ft-lb for all P60 Series Gearboxes. It is possible to mount motors that will exceed this in higher gear reductions. Higher reduction gearboxes should be utilized primarily for speed reduction. Designs utilizing a P60 gearbox / motor combination that will exceed 35 ft-lb should include a method of limiting torque to prevent damage to the gearbox.
<<

[motiondave]

if thats the motor you want shown in the video, thats pretty small.
If you are prepared to buy a motor and test it, that may be the way to find out.
I originally bought 2 motion dynamics motors based on specs, but paid for them and abused them to show they are fine. Quite a few, including the supplier didnt believe as to what I was going to do with them.

[densohax]

Motiondave,

Well that's what I did..

BUT instead of buying the whole assembly (the motor is 8$, the gearbox ~60 I think) I bought only a similar motor with lower specs (58 amps stall, about 40nm)

I will build my gearbox, in fact, this is very very experimental.. I have a 3d printer at my disposal and while I understand that the load at hand is probably greater than the tensile strength of ABS plastic, I have to prove that I can engineer something quite cheaply that will perform as well.. At least, my dev cost is only 8$ instead of paying 100s to test the gearbox! ..

So I designed a hypocycloid 1:144 gearbox, I'm impressed by the small size needed to make the gearbox and this is very interesting, in that, I can scale up the parts a lot to make them harder to break.. So if this all goes well, I could have a 8$ motor and the cost of plastic (probably 2$ top) for an axis!


I do think however that stopping or changing motor direction is going to take time at 20'000 RPM! .. But this is all testing..
I'm planning to put a rotary encoder on the input shaft of the motor and as I said, a minibike disc brake for holding torque.

My gearbox is about 65mm in length, pretty small.

I guess that with counter-weights or using ZFL springs I could counter-balance the whole frame and thus make it work..?


Edit: I essentially did the same thing but in plastic : https://www.youtube.com/watch?v=cnJCWX2nr4M

[motiondave]

forget the springs, just balance the frame right for you and adjust with counterweights of you have to.
58amps stalll is still high, you will need a BIG h-bridge to handle this.
20,000 rpm changing direction....dunno about this.
give it a whirl

[densohax]

Whirl in progress!

Are you familiar with Just Herder zfl balancing mechanism?
https://www.youtube.com/watch?v=-4gTBIFRWls at about 1:30

With a ZFL spring he can make the mass virtually weightless. Well it's a counter-balance without a mass in the end...

Yep 58Amps, I'll need good HeatSinks.. But I think I'll current limit the H-Bridge with a chopping driver to not go over 40 amps (I want to use cheap chinese 12v power supplies)

[densohax]

https://www.youtube.com/watch?v=RB92j2MO3Mk

This is the motor I bought. In this video it's on a 1:64 gearbox!
It looks fine to me for the job at hand.

Oh and btw, the stall amps is 85 not 58