Using RC gear to drive a grain mill

[Sammus]

Howdy, I wasn't sure whether this was considered a project X, but it doesnt seem to fit any other category.

I have a spare turnigy hv100 esc kicking around and a big kick ass grain mill to motorise (homebrewing).

I was thinking of getting one of those big cheap outrunners from hobbycity and a spider coupler to direct drive the mill.

Thing is, I only want the mill to be turning at about 200rpm (give or take). So running max voltage etc full throttle will be much higher than that (obviously). Does anyone know roughly where peak power would be delivered in a motor like that? Could I use my Tx to limit the rpm and still expect to get anywhere near 500W output?

cheers

Sam

[johnrobholmes]

You will certainly need some geardown. 200rpm at the mill head, and let us say that you spin the outrunner at 5k- which is slow. You will need 25:1 geardown. Not too shabby, an easy two stage gearbox.


Power will just be a function of the amp draw and RMS voltage applied to the motor. If the motor is big, 500w is no problem. If it is small you will want more geardown and voltage.

[Sammus]

Fair enough.. Well there goes the idea of using my spare Ammo 36-50-3300, rated at 833W continuous (more than enough). That's spinning at like 50k rpm. A 250:1 geardown haha. I guess I could use a worm drive. Pity parts to build these things are expensive and hard to come buy in Oz. The only one I've seen is that plastic tamiya kit haha. Hmm. Maybe a combination of pinions and spurs. I think RR make a 12T 48p, and with the 90T traxxas spur, thats what, 7.5:1. So if I string together a bunch of those... its be a 3 stage i guess, without such extreme stepdowns either. Any cheap tought crawler gearboxes you recommend JRH, that might do the job or me? Perhaps an outunner would be a better idea than an inrunner and a complex gearbox :p

hmmm...time (and fundage) will tell!

[johnrobholmes]

Yeah, a few spur and pinion setup would do the trick. Outrunner would certainly reduce the need for geardown.

[traxxasrevony]

this should be the best project ive seen thus far. whats better than RC an homebrew put together

[BrianG]

Are there any inline planetary gearboxes that will fit? Something like this? They usually have ratios somewhere around 4:1 to 7:1. Two 7:1 drives will get you a 49:1 ratio.

With a large reduction ratio, you should have TONS of torque at the output! Using your 50k rpm and 833w figures (which I assume means you are using 4s?), that would be ~6ft-lbs of torque (assuming 50:1 ratio).

[mjderstine]

subscribed to this one. gotta see the finished product when you get there.

you are trying to go cheap right?

http://www3.towerhobbies.com/cgi-bin...=GHIGPM&P=0&S=

look around there, it is full of them. and at a nice price too.
http://www3.towerhobbies.com/cgi-bin...?&I=LXHUX2&P=0

that was the best gear i could find on the list, looks to be alloy makeup too.

[BrianG]

I was just thinking a bit more about the worm-drive idea. Sounds like it would be a good method to quickly bring down rpms, but if the motor is spinning at ~50krpm, won't there be quite a bit of wear on the spiral and pinion gears? I mean, there's a lot of "sliding" involved (as opposed to meshing). Just curious...

[mjderstine]

well i know you can get a nice spider gear that holds a lot of power fromt he new Kyosho Rock Force.

https://www.shopatron.com/product/pa...5411.42175.0.0
https://www.shopatron.com/index/410....5411.42175.0.0

might have to buy a couple components to get the whole thing, but it is strong and SLOW

[Sammus]

Ah yes, the kyosho rock force gearbox was one thing I had in mind. Brian is definitely right about the wear though. I'm thinking a regular gear reduction will have to be the go.

mjderstine: yeah I've looked at those a bit, the one you linked looks a little small (2mm motor shaft, 24mm max motor diameter)

The Neu gearboxs look cool, but the idea was to save money, a few of those is a few hundred, I could easily get a cap start AC motor and a few pulleys to drive the thing. I'll keep looking, see what I come up with.

Any more links or ideas or cheap planetary gearboxes come up, link me up ;)

Cheers

I also just realised I need closer to 100rpm..should be run haha. So far the plan is to use my 3300 on 4s A123 and 3 step downs involving a 90t spur and 12t pinion. Thats a about a 420:1 drive ratio.

Anyone got any ideas on how to mount the spur gear to a shaft? my mind extends about as far as using the slipper hub to attatch it...still costs about $20 per reduction step... and I was hoping to use stuff I already have. Oh well, see how it goes. Pity I'm not a machinest, this would be much easier haha.

[johnrobholmes]

How about a starter for a glow airplane? Those spin pretty slow and have great torque. Brushed motors, but would be really cheap.

[traxxasrevony]

and you could run the starter motor of a power supply
a cheap one at that.

[Sammus]

Hmm here's a big big spur that looks like it'll be easy to attach to a shaft (easier than the bolt on slipper type ones anyway

http://rc-mushroom.com/product_info....ducts_id=13412

Using them in 3 steps I could probably get around the step down I need. I've already got a million pinions so I should be able to work something out. I wonder how that little centre pin in the spur gear will hold up under large torque? it's a much cheaper gear to use than running 3x traxxas slippers and spurs, and if it can hold up it might be the go...

Bah here I am working in all 48p when my motor is a 5mm shaft...

Anyone know how many rpm or how much power the 12T traxxas 550 puts out? (my other spare motor).

Or I guess I could run my 3300 in my rustler and use the feigo 9L 1/8", which I imagine be more than ample haha.. lower rpm too.

[Sammus]

I don't want to guy buying new motors, I can get a geared scooter motor with plenty of power for 89aud (like 50usd at the current rate haha) that will bolt directly to the mill.

I just thought it would be cool it use rc stuff I already have. I thought maybe a few gears etc, spend 20 or 30 bucks. if it gets any more exp. I may as well just buy something built for the job ;)

what power supply has a starter motor? all mine the only motors in them are the fans...

[traxxasrevony]

no he meant use a motor like this
http://www3.towerhobbies.com/cgi-bin...&I=LXJC37&P=FR

and i meant use a power supply like this to provide power to the motor above.

http://www3.towerhobbies.com/cgi-bin...&I=LXWGU7&P=ML