Traxxas Stinger Motor Specs

[seamus]

@linuxguy

@Seamus

That depends entirely on how far you’re willing to gear it down. You’ve got a whole lot of revs to work with there, and you can build a gear train with as tall a ratio as you like, so long as you realize that more torque == less speed.

Oh, I know! It’s the torque I am thinking about. I bet I’d get some incredible torque and still be able to get decent speed out of the Stinger motors. They are not very expensive either.

8-Dale

The motors themselves are cheap and readily available, but then there’s the question of achieving the gearing that you want. Depending on how you’re set up for a shop, the cost of the gears, shafts, collars, bearings, mounting blocks, etc. may well make your homebrew gearing more expensive in both time and money than simply purchasing off-the-shelf gearhead motors. You’ll have to google around, but I’m sure you can probably locate some company or another that sells them. Sure you won’t have the flexibility that you would have with custom-designing your own geartrain, but unless you’re shooting for some very specific speed or torque range, it may be a lot quicker and easier to just go with something stock.

Alternately, if you aren’t so concerned about the space required, there’s always the time-tested method of hacking toy gearboxes, though most R/C cars will run awfully fast for an indoor bot. Also, your Stinger motor is a lot bigger and beefier than the motors found in toy cars; it may well need something built a bit more solidly than your average toy car transmission.

[linuxguy]

@Seamus

The motors themselves are cheap and readily available, but then there’s the question of achieving the gearing that you want. Depending on how you’re set up for a shop, the cost of the gears, shafts, collars, bearings, mounting blocks, etc. may well make your homebrew gearing more expensive in both time and money than simply purchasing off-the-shelf gearhead motors.

I don’t have any sort of shop or ability to fabricate at all. I am not the mechanical sort, and do only as much mechanical stuff as I have to in order to build my robots. I would have to have somebody else do any required fabrication.

Maybe this project isn’t such a good idea afterall, but it is an interesting idea. I don’t mind buying ready made components if I can get the results I am looking for.

8-Dale

[seamus]

@linuxguy

I don’t have any sort of shop or ability to fabricate at all. I am not the mechanical sort, and do only as much mechanical stuff as I have to in order to build my robots. I would have to have somebody else do any required fabrication.

I haven’t played with one at all, but perhaps the PHGM-19] planetary gearhead motor would be an option, here. The stats sound like a standard 500-class motor, which would be somewhat equivalent to what you’ve got in the Stinger. You could probably replace the stock motor with your Stinger, and maybe get a performance boost.

Ooh… Just had a thought. [size=67](that always hurts)

On the other hand, perhaps this isn’t the best approach to take, after all. I just remembered an important aspect of R/C motors: timing.

The position of the brushes in relation to the magnets make them more efficient at rotating in one direction over the other when running at speed. In higher-performance motors, the brushes are accessible, rather than being enclosed in the motor can, and can be replaced with “timed” brushes to advance th etiming for more speed, or retard it for more torque. For running in modified classes, they have motors with adjustable endbells, which allow standard brushes to be rotated, so you get maximum contact area and pressure, while still adjusting the timing for the performance you want.

Translation: Depending on its design, your stinger may not spin with the same speed and/or torque in when reversed. This would translate to uneven performance, even when fed through identical gearboxes on either side of a robot chassis - your robot would arc to one side or the other. dynamic speed control and a good PID algorythm could probably compensate for some of this arcing, but the differences can be fairly dramatic, particularly with large timing differences.

If it’s a “zero-degree” motor, you would get approximately the same performance in either direction, but with the Stinger being a closed-can type of motor, you won’t be able to adjust the timing if it’s not. If I recall correctly, stock class motors used to have around 24 degrees of non-adjustable advance timing built into them, meaning that there was a marked difference in their performance between running in clockwise and counterclockwise directions.

Keep in mind that the last time I raced was in the early 1990s, so things have probably changed a lot since then. You may actually have a zero-degree motor, which will run equally well both directions, or you may not. If you can, take a current reading with the motor running in one direction, and then in the other. Keep in mind that these beasts will draw a whole lot of amps, particularly when loaded, so make sure you use an ammeter than can handle the oomph. At the very least, make sure you know how to change the fuse in your meter’s ammeter section, and have spares handy before you start. (I’ve killed a few meters this way)[/size]

[seamus]

Also:

Don’t underestimate your ability to build things without a shop. With some basic hand tools and a bit of patience and persistence, one can achieve impressive feats of fabrication, even in the living room of an apartment. Admittedly, I wouldn’t attempt a gearbox, where tooth mesh distances are critical, but I’ve even managed some basic mechanical puzzle locks with little more than a jeweler’s saw, some needle files, and a handful of other basic toolbox tools.

Just remember: the Dremel tool is your friend.

…and no power tools after 9:00 PM.

[dimrobot]

@linuxguy

Well, so much for using a Sabertooth 2x10 R/C to control this beast then. Dang, this might be more expensive a project than I can handle. But then, now that I think about it, all robot projects are pretty expensive if done right, and it takes me months to build one robot due to limited income.

Actually if its heatsinked to a metal plate or chasis, a Sabertooth 2x10RC would work okay here, as long as you don’t need to push things around at stall. The overload protection will limit stall current to a couple amps.

Not good in a sumo or combat application, because you’re easy to push around if you’re hitting current limit, but for a rover it’d work out with no problems.

The really hot wind R/C car motors aren’t a good fit, but cheap cordless drills or stock RC car motors aren’t a problem. Just keep the controller cool by mounting it to a metal chasis or plate (or put a fan blowing on it if you’re running into thermal cutout)