DC motors?

[systemoverblow'd]

Any one here know a lot about low voltage DC motors? Or know of a great online resource? Looking for high torque, low speed (variable), able to run off a 14.8V 95Wh battery. I can give dimensions of the motor I'm trying to replace if anyone knows their shit. Local hobby shops have been unhelpful.

Looks very similar to this:



Thanks.

[stevesmith7]

Is that a geared motor? Picture looks like one. High torque, low speed = geared or big magnets, big current.

[systemoverblow'd]

See, I don't even know what that means. The one I have has a gear bolted onto the shaft and needs to spin at a constant speed depending on the voltage applied. It turns at certain speeds based on a knob between it and the battery. Does that make sense? I know exactly zero about this crap. It has to be able to spin a heavy load very slowly.

[systemoverblow'd]

Does this information help you at all?

[abraham]

Are there any part numbers or specs on the case of the motor? That sometimes is a good place to start.

[stevesmith7]

See in the picture there appear to be two parts to the device. The front part where the shaft sticks out is almost certainly a small gear box. The back part is the motor. These small motors don't like to make that much torque to begin with and at low speeds the only way to get torque would be to have big magnets and run a lot of current through big windings. That all equals big size. By using a gear reduction the motor can run at higher rpm and the gearbox multiplies the torque while reducing the speed.

Here's a place that seems to have a big selection:
https://www.servocity.com/html/3-12v_gear_motors.html

Never done business with them, just the first interesting thing I saw on a search.

[stevesmith7]

Motor speeds are measured in rpm so I don't know what to make of the sec/m spec. Depending on the gear attached the conversion could be anything.

[stevesmith7]

One thing in the spec that looks challenging is the ratio between max and min speed. It's about 500:1. If full voltage (14V) gives max speed the motor would have to able to run at an extremely low voltage to work. My guess is that the controller is some sort of PWM (pulse width modulation) system to pull this off. If that's the case you just need to match the max rpm to whatever you have.

[systemoverblow'd]

Figured it was a long shot. Looks like there was at once a label on it but not anymore. No other markings that I can read. It is for a motorized photo slider, that's why the distance is there. No other info is available I am afraid. Kind of why I wanted to bring it to a specialist so they can check and get me what I need. Unfortunately, Boston isn't a hotbed for DC motors.

[systemoverblow'd]

Thanks for the help guys... looks like this is probably impossible to figure out with the information I have and just some stupid pictures. Oh, and those six threaded holes on the face are absolutely a necessary part of the equation.

[stevesmith7]

Well if the gear attached to the motor ties into a linear track you can compute meters/rpm and then figure out max rpm out of the motor. BTW, the offset output shaft is a dead giveaway it's got a gearbox on the end. Motors are never offset like that. That will make finding a direct replacement tougher.

[Vt-Freeheel]

I am going to build a barn door tracker and buying from this company, lots of dc motors here. Good luck

[systemoverblow'd]

So after getting the balls to dismantle it, seems a couple cogs on one of the gears is smashed and that's why it is hanging up. Would finding an assembly like this be easier, because the motor itself is running fine without the gearbox attached.

[stevesmith7]

It's always the gearboxes that fail. There's probably something like 3000:1 gear reduction so even the small torque of the motor gets magnified a lot.
Don't know where to look. Without knowing the manufacturer you're pretty much SOL.

[systemoverblow'd]

I just found http://www.anaheimautomation.com/ which looks promising. They have many that look just like mine, right down tot he mounting holes. I have an email out to them now to see if they would be willing to accept me shipping my bad gearbox (and motor) to them and see if they can identify and replace it. We'll see what they say. Hope they know enough and are willing to do it. They are dirt cheap so I may as well just buy a whole new one that works.

Thanks for all the information and help. I would be lost* without it!

*kind of still am

[systemoverblow'd]

I am going to build a barn door tracker and buying from this company, lots of dc motors here. Good luck

Missed this. Thanks! If the other company won't help, I'll give them a shot.

[Vt-Freeheel]

They gots the gears also.

[FJ62]

I found my local Grainger Electric Motor store to be super helpful (they replaced an old DC motor on a 100 year old letterpress for me, helped me set up everything, etc.

Looks like there are some near Boston (Everett, Watertown, etc).

http://www.grainger.com/content/find-branch-location

[systemoverblow'd]

They gots the gears also.

Holy shitballs, I could rebuild myself if I measure accurately! I already tried taking each gear out and inspecting them. Looks like more than one is damaged. Anyone around got a set of calipers I can borrow?

I found my local Grainger Electric Motor store to be super helpful (they replaced an old DC motor on a 100 year old letterpress for me, helped me set up everything, etc.

Looks like there are some near Boston (Everett, Watertown, etc).

http://www.grainger.com/content/find-branch-location

Didn't even think of a supply house like Grainger. Good call! This might be easier than I thought!

[brice618]

I bet a hobby shop would be able to handle that. Either replacing the gear / gear box or finding the motor. Look for RC airplane/ car stores. Just a thought if your other place can't help.

[Harry]

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[riser4]

Any one here know a lot about low voltage DC motors? Or know of a great online resource? Looking for high torque, low speed (variable), able to run off a 14.8V 95Wh battery. I can give dimensions of the motor I'm trying to replace if anyone knows their shit. Local hobby shops have been unhelpful.

Looks very similar to this:



Thanks.

So did you contact the manufacturer of the thing the motor belongs to?

[systemoverblow'd]

So did you contact the manufacturer of the thing the motor belongs to?

Obviously that was the first thing I did. But it's the weekend and was looking for options for when they tell me to "Ship it back and we'll send you out a new one." Because if they want me to send the whole slider back (It's big and heavy), I'll just buy a new motor because it will be cheaper than shipping. Just keeping my options open.

[mangle]

I design such things for a living. Without looking too closely, I can pretty much promise that it's a standard Mabuchi part. Narrow it down with dimensions, then figure out speed/voltage to get the motor constant.

[riser4]

Obviously that was the first thing I did. But it's the weekend and was looking for options for when they tell me to "Ship it back and we'll send you out a new one." Because if they want me to send the whole slider back (It's big and heavy), I'll just buy a new motor because it will be cheaper than shipping. Just keeping my options open.

Heh. And around here that is not all that obvious. Yes, good to have options. So what did they say now that it is no longer the weekend? They put a new motor on the truck and you'll have it tomorrow?