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Jul 23, 2017, 10:24 AM
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Motors required for battery operated rotary brush


Hi, i am making a battery operated rotary brush for a project, if anyone could steer me in the right direction i would be very gratetful.
Some requirements
I had planned to power the rotary brush using brushless motors on each end.
The brush weighs about 300 grams and the surface is smooth. i want the brush to spin at about 200-400 rpm and very minimal force will be applied as the brush will be doing the work.
I want the motors to not be too long about 25mm not including shaft but they can be up to about 50mm wide.
The total weight of 2 motors, speed controllers and battery to potentially power this for up to an hour must be below 750 grams.
I have attached 2 photos to roughly show what i am trying to make.
Is this possible?
if not what are my limitations/options?

Thanks in advance.

Karl
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Jul 23, 2017, 11:36 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Welcome Karl, this subforum is about building and (re)winding motors, not about off the shelf motors.
I have asked moderators to move your thread to the Power Systems subforum.
More readers, more input

Prettig weekend Ron
Last edited by Ron van Sommeren; Jul 24, 2017 at 10:54 AM.
Jul 23, 2017, 08:20 PM
Registered User
Thread OP
Oooops, thanks Ron.
Jul 24, 2017, 03:46 AM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by karl christopher
Hi, i am making a battery operated rotary brush for a project, if anyone could steer me in the right direction i would be very gratetful.
Some requirements
I had planned to power the rotary brush using brushless motors on each end.
The brush weighs about 300 grams and the surface is smooth. i want the brush to spin at about 200-400 rpm and very minimal force will be applied as the brush will be doing the work.
I want the motors to not be too long about 25mm not including shaft but they can be up to about 50mm wide.
The total weight of 2 motors, speed controllers and battery to potentially power this for up to an hour must be below 750 grams.
I have attached 2 photos to roughly show what i am trying to make.
Is this possible?
if not what are my limitations/options?

Thanks in advance.

Karl
Hi!

They simply used to put a timing belt, and a gearing on a small diameter motor in this case so the motor spins at 5x-50x more speed because they have little torque.
Not sure why would you use 2 on 2 ends, but an 50mm diamater motor can definitely give you some torque for a brush, you can use a higher Kv rated motor at partial drive voltage to get part of the "rated power at rated RPM" if that is ok with you you can for example use an 500W/8000RPM outrunner at 1/10 supply voltage to get 800 RPM at 50W power, the torque is about the same, rewinding is also an option.

For that low RPM and low power? you could use stepper motors from a printer if it doesn't matter if it is less efficient and heats up a bit more.
Jul 24, 2017, 04:46 AM
Registered User
Thread OP
Oh ok, you think 2 motors is overkill? I didn't know the potential of the motors.
I had a look at stepper motors and they look very good for my application, maybe 1 would suffice.
https://littlebirdelectronics.com.au...v-0-28-a-phase
Would something like this provide enough power? Also how do i calculate and regulate rpm for these motors?
Also what is the efficiency of stepper motors vs a brushless with reduced voltage?
Jul 24, 2017, 08:45 AM
just look at it smokin'
z-matrix's Avatar

brush driver power system


Quote:
Originally Posted by karl christopher
Oh ok, you think 2 motors is overkill? I didn't know the potential of the motors.
I had a look at stepper motors and they look very good for my application, maybe 1 would suffice.
https://littlebirdelectronics.com.au...v-0-28-a-phase
Would something like this provide enough power? Also how do i calculate and regulate rpm for these motors?
Also what is the efficiency of stepper motors vs a brushless with reduced voltage?
Yeah, 1 should be enough, at that size you asked there are BLDC motors over 500W power,
bldc motors need a BLDC ESC, for your application a sensorless type would do, that is an aeroplane or helicopter bldc esc connected to an 50mm outrunner bldc motor.
btw you might even be able to integrate a motor in your brush? an outrunner motor works as its outside casing rotates...
https://en.wikipedia.org/wiki/Brushl...electric_motor

stepper motors need a stepper motor that is usually used for open-loop positioning they hold still and are able to move 1/200 of a rotation or even smaller steps
here is the schematic of a stepper motor driver:
http://hades.mech.northwestern.edu/i...Driver_Circuit
if you can get dead inkjet printers free then you can get stepper motors out of them probably, some has brushed motors though...
http://www.smcelectronics.com/printrep.htm
this is fairly thin and large diameter, also powerful for example:
Paper Stepper Motor Assembly. (RFE)
Used in many HP printers including Deskjet 540/600/600C/
610C/612C/615C/660C/670C/672C/680C/690C/692C/693C/
694C/695C/697C and many other HP models.
Shaft has 16 tooth gear.
Approx. size: 1 3/8" x 2 1/8" diameter,
gear size: 7/32" x 3/8" diameter.
HP part number: C2164-60045.


the cheapest hack would be, I suggest you grab 2 high power computer fans with large hub diameter and 12V 1A - 3A current specifications, break its wings and epoxy them to the 2 end of your brush...


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