12v Dc Motors?

Question

For my upcoming project(no hints, but cardboard is a material) I need 2 12v dc motors to be run off the h-bridge in the store, which means the max motor amperage is 2.5Amps.

Size isn't big but the robot will be mid-sized. 5 pounds or so of torque per motor if possible.

If it could have a wheel that would be awesome!

Anyone who can link me to some motors will be put on the credits list for the future bot.

Thanks guys!

Troy · Answer

Servocity.com has a few gearmotors. See if any will work for you. ServoCity precision gearmotors Cheaper but lower torque ones are here since you're probably going to be light weight.

Robot Doc · Answer

Consider getting a Roomba "for parts" , it will come with a couple of drive motors rated at 12volts.

CardboardHacker · Answer

Robot-doc, would they be enough? Troy, I like the site but I priced the stuff needed and it's almost $100. Any other sources are appreciated.

CardboardHacker · Answer

Will these work Robot-Doc? Are these what you talking about? www.ebay.ca/itm/Roomba-Discovery-Primary-Drive-Wheel-Assembly-/380235547224?pt=LH_DefaultDomain_0&hash=item5887ce0258

Or this? www.ebay.ca/itm/Roomba-500-Series-Left-Wheel-and-Motor-510-530-540-/200754973319?pt=LH_DefaultDomain_0&hash=item2ebdedca87

CardboardHacker · Answer

I found this motor: www.ebay.ca/itm/300rpm-Playmobile-Assembled-Tire-Driving-W-37GARH-DC12V-Electric-Speed-Motor-/161096782513?pt=LH_DefaultDomain_0&hash=item25821dd2b1

Will it work? I plan to pwm it down if I get 2. Has enough torque. 2 motors =9 pounds of torque. Plenty!

Dunning-Kruger · Answer

@Technopro Those will work, but 300rpm is a tad fast I would think... If you pwm down it won't have any torque left... It is a motor definitely meant for high speed.. I like motors of around 100rpm on the output shaft... A Roomba is close to that (100rpm or so) or even possible a little less...

CardboardHacker · Answer

Still to fast? Rated speed under load is 152Rpm with 2.8kg(6 pounds) of torque. Which leaves me a little space to pwm it down a little.

www.ebay.ca/itm/12V-200r-min-Playmobile-Assembling-Tire-Drive-With-37GARH-DC-Electromotor-/161096790486?pt=LH_DefaultDomain_0&hash=item25821df1d6

Troy · Answer

@Technopro, No problem. I know it can be pricey.

Danger! · Answer

I don't know if any of these will work, but this site is reasonably priced. www.goldmine-elec-products.com/products.asp?dept=1300 You might look at this one. www.goldmine-elec-products.com/prodinfo.asp?number=G17949

CardboardHacker · Answer

Danger!, the rpm on the motor in the second link is way lower than I can deal with. Thanks for the link though. What does everyone think of this motor and wheel? www.ebay.ca/itm/12V-200r-min-Playmobile-Assembling-Tire-Drive-With-37GARH-DC-Electromotor-/161096790486?pt=LH_DefaultDomain_0&hash=item25821df1d6

Danger! · Answer

Actually, now that I look at that one again, it is pretty slow. There are others though. (edit our last two messages crossed)

Danger! · Answer

www.goldmine-elec-products.com/prodinfo.asp?number=G18337 This one might be in your speed range.

Danger! · Answer

The one that you are looking at would probably do the trick. The description mentions robots, so I would guess that it is not made just for racing cars. You wouldn't have to buy tires, anyway.

CardboardHacker · Answer

Your latest link could work, its just about trying to find a wheel.

Troy · Answer

Remember to figure the circumference of the wheel you're attaching it to. Circumference=3.14  X diameter. The circumference is the distance traveled per revolution. Divide your revolutions per minute by 60 to get turns per second. Say for instance you have a 3" wheel and a geared motor going 120 rpm. 120/60 is 2. The circumference is 9.42. So 2 revolutions of 9.42 is 18.82" per second. Kinda zippy. Granted that the rpm rating is when not under load but you can get a better picture of how fast it may go.

CardboardHacker · Answer

ok so seeing as I'm so tired I didn't understand that what do you think is better? 300rpm with 2kg of torque or 200(152)rpm with 2.8kg of torque?

Troy · Answer

I vote for more torque and 152 or 200 rpm. That still gives an overhead for pwm to get slower. Just my opinion. Edit. I just looked at the link you had. I didnt realize the speed was already in there with the wheel size. Unless Im missing something Im coming up with over 32K mm per second. 68mm tire size X 3.14 X 152 rpm = 32455mm per sec or 1277.7559 inches per sec or 106.48 feet per sec. Im a bit tired it seems. EDIT: I slipped up and didnt realize I forgot the answer was per minute not per sec.

Danger! · Answer

I checked the math Troy. The wheel diameter was 65mm. That translated to 2.559 inches, giving a circumference of about 8 inches. Turning at 152 rpm would be 1216 inches per minute, or about 20 inches per second. It would cross a good size room in about 10 to 12 seconds.

CardboardHacker · Answer

So we have it! Ill get the 200rpm motors Got my ping sensors from china last night and inspected them. Some for roli mega, the others for my next bot.(trying hard not to spoil the surprise!)

CardboardHacker · Answer

Thought i'd post product info for anyone who finds this thread. Product Name: Mini DC Tyre Motor Assembly; Motor Model: 37GARH; Voltage:12VDC; Rated current: 1.1A; Motor No load speed: 200r/min; Motor rated speed: 152r/min; Motor rated torque: 2.8kg.cm; Tyre: 6827mm(DT); Shaft:Dia 37mm Long; Motor Speed: 653.14152mm/s; driving force: 2.8 - 3.25kg Total Size: 65104mm(DH); Material: Metal, rubber; Color: As picture shows; Weight: g; Package Content: 1 X DC Gear Motor + 1 X coupling + 1 X stand + 1X tire;" www.ebay.ca/itm/12V-200r-min-Playmobile-Assembling-Tire-Drive-With-37GARH-DC-Electromotor-/161096790486?pt=LH_DefaultDomain_0&hash=item25821df1d6

Troy · Answer

@danger, thx, lol I knew that I couldnt be right on that math.

Danger! · Answer

No problem. The first time I did it, I was thinking it was 20 feet per second. I told techno that it would be way too fast. Then I thought about it and had to go back and edit my post. 20 Inches per second is still a little quick for a robot but I am sure that with pwm he can get it into the right ballpark.

CardboardHacker

12V Dc Motors?

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