So if I have an average rpm of 100 rpm and the rates torque is .45 kgcm, does that mean this has a power output of 4000 Watts?

I know this answer is coming to you 3 years too late - and you probably figured this all out. Just in case - here is how you can calculate the power from the torque and RPM. A couple of quick notes: Torque is force times length - kg is not a force but a mass. If the "torque" is given in kg*cm - then this is not a proper torque number. It should be in Newton*cm. Newton is the unit for force and kg for mass. The force a mass experiences here on earth is the mass multiplied by the earth's acceleration of the mass in the earth's gravity. This acceleration is 9.81 m/s/s (meters per seconds squared). This unit is the same as N/kg (not that readily visible - but for now we'll just accept that as correct). Now we can calculate the proper torque by multiplying the two numbers: 4.5kg*cm * 9.81 N/kg = 44.2 N*cm. Power is work done per time - work, energy and torque are identical units of measure - force times length - the continuously delivered torque is the same as the work done by the motor. However, for the power to be correct we have to express work in N*m (SI units) - not N*cm. So we have translate N*cm into N*m. 100 cm = 1 m or 1cm = 0.01 m. We can just simply replace the cm with 0.01m and well get the torque (work) in N*m - 4.42N* 0.01m = 0.442 N*m. Next: power is Nm/s in SI units - that means we have to express 100 rpm in rps (revolutions per second = rev/sec). 1 min = 60 seconds. 100 rpm = 100 revs per 60 secs = 100/60 rps = 1.7 rps. Now we can calculate the power in N*m/s: 0.442N*m * 1.7 rps = 0.74N * m / s = 0.74W of mechanical power - which is even less power. Of course that's only correct if the 4.5kgcm number is correct for the motor. Some of the suggestions were to use the electrical power of the motor to estimate the mechanical output power. That too is a legit approach - however, that power setting given must be under the same conditions for which the mechanical output was given. E.g. the motor must run at 100 rpm and deliver the torque given - only then the current draw by the motor and the voltage accross the motor can be used to calculate the approximate mechanical power. For example - if the motor draws 1A at 12V when stalled out (motor is slowed down to a stop), then this is not the same condition as running the motor at 100 rpm. Sometimes the specifications given for those products can be a bit questionable.

Can this fit into a 1/4” metal rod? With a shaft collar or something?

If you are widening a coupler and you can, use a drill press or milling machine. Be sure the setup is as rigid as possible. Use a "reamer" 1/4" in diameter if you can get one. They are special purpose tooling but get used all the time for this exact job. They cost a few dollars. Use very low speed or even turn the chuck by hand. Do not use a hand dill at full speed with a twist bit. I would rather use 400 grit sand paper or fine abrasive padding than any sort of standard drill and bit.

How many rotations does this motor make a minute

As stated on the label.... 100 revolutions per minute (rpm)

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Reviews

T**M

Strong, and smooth

Works perfectly! Much more powerful than I expected.

13.11.2025

N**1

Tiny Little BEAST

This little guy is super tiny, yet an absolute BEAST. Manages to keep the 2.5 rpm (5rpm motor geared down to 2.5) while rotating the huge 26" diameter and over 30" long horn on my siren. 1/2 Scale ACA Hurricane MKII. $15 motor, comes to my door in like 2 days. Absolutely worth the money, great little motor. Uses M3 machine screws to mount it. With no load, it's pretty much silent. With a large load, it makes some noise but is still pretty quiet in general terms. When it's on the pole rotating the head, i can barely hear the motor at all. With the chopper running, it's literally impossible to hear this motor.

1.01.2025

W**Y

Great for light duty projects. Not too noisy. Good speed control.

The motor is small, compact, and not as noisy as I expected from the reviews. It had plenty of power to handle my design but only pulled 220ma, 1/5 of what the specs show. I haven't tested it at stall but I would imagine that's where they got the current spec of 1.1A. It responded well to PWM and input voltage changes for speed control. All in all I am pleased with it. I only gave it 4 stars because of the misleading specs.

23.10.2024

R**E

Well Built Good Quality and Very Quiet

Well Built Good Quality and Very Quiet. This is the motor I use for my spool rewinder. It has excellent torque. I don't need to say much just watch the video. I'll definitely be using this brand for other projects.

10.06.2025

J**.

Has been working reliably for a year, good torque, perfect for Arduino

I am using this for a Halloween prop where it hoists a spider (one of those 4 foot spiders you can buy at the Halloween stores) up to an overhanging branch on our front yard tree. The spider weighs about 13 oz and there is some friction in the system but the motor hoists the spider quite handily at about 0.5 m/s. It doesn't sound like it's struggling and stays cool. I'm controlling it through a Pololu motor driver and Arduino Nano and it seems to work fine with this setup. The motor makes a little noise but you can barely hear it out on the sidewalk. All in all very happy with this motor.

30.12.2024

F**G

good

works good

10.10.2025

J**J

Great!

Very nice motor, plenty of torque. Size measurements provided on the Amazon web page were accurate.

30.07.2025

O**T

Good product

Very nice little power pack

11.09.2025

ASIN	B072R57C56
Best Sellers Rank	#6,433 in Toys & Games ( See Top 100 in Toys & Games ) #12 in Hobby Remote & App Controlled Vehicle Parts
Brand Name	Greartisan
Customer Reviews	4.5 out of 5 stars 1,559 Reviews
Item Dimensions W x H	1.46"W x 1.46"H
Item Height	3.7 centimeters
Item Weight	195 Grams
Manufacturer	Greartisan
Material Type	Metal
Model	Greartisan
Model Name	gear
Speed	100 RPM
UPC	766330626869
Unit Count	1.0 Count
Voltage	12 Volts

Greartisan DC 12V 100RPM Gear Motor High Torque Electric Micro Speed Reduction Geared Motor Centric Output Shaft 37mm Diameter Gearbox

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