Core Electronics Forum

Choosing the right motor gearbox for job

HI All
I’m searching for a small constant speed DC or AC Gearmotor running approx 10rpm solution.
I’ve started building Marble Ball tracks (I tried to attack pics etc but it wouldn’t let me, one footage of one at link below) basically a small wire roller coaster where marbles roll around the wire tracks, I need a motor solution to lift balls from bottom back to top
my problem is all the footage I have on building them, the motors other fabricators use is so broad- some use AC- some DC, some brushes some brushless, some use speed controllers and encoders etc so need your advice and input, I’ll be building a large volume of these once mastered so hopefully I can purchase all materials from you guys once you assist me

Warmest Regards
Sean

Hi Sean,

The absolute easiest way to go about a slow-moving motor would be to get one with a gearbox attached. The closest speed I could find to your target in our store is 6RPM, but you could likely get away with one with less reduction (more speed) and drive it with a PWM signal or lower voltage in order to slow it down.

Using encoders and brushless motors will provide a truly silent experience, with excellent speed control, but such solutions are niche, and a little overpowered for what you’re looking to do I imagine:

Another option to consider would be stepper drivers with silent motor boards like the TMC2209, check out Geoff’s thread on his crane for his migration to silent step sticks:

I wrote half of this post a while ago, and only just came back to it, so there is likely more I wanted to recommend, but have a look at what I’ve recommended so far and get back with your thoughts :slight_smile:
-James

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Hi James

Thanks so much for the detailed reply, very much appreciated, I’m on site mate so don’t like replying in detail on iPhones, soon as I get back into office we’ll communicate and I’ll definitely get you to help me in purchasing some motors etc

Cheers

Sean Haggart

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G’day James. See video below. We have achieved incredible accuracy with the stepper motor plus a pile of controllability via keystrokes and Putty, thanks to Michael’s unbelievable code. We have in fact moved on from this video and now can nominate a degree destination. Michael says there is more work to be done to tweek it even further.
The code will eventually be made open source.
Microstepping and accuracy - YouTube

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Hi James

This motor gearbox looks perfect for what I want, I wouldn’t want to go slower, a little faster if anything,

excuse my lack of knowledge but what is the PWM signal you spoke off, I’d obviously need to purchase any switches, wiring , battery/power charger etc involved as well mate, they’ll need to be compact as possible

As I said this will becoming full scale with my business/sculptures/water features and your input has been the most informative and engaging out of all the Electonics suppliers I’ve contacted
so Thank You again, its greatly appreciated.

Talk soon

Sean

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Hey Sean,

Sounds like a fun project! PWM is a very fundamental technique for controlling an output signal simply by switching it on and off very quickly (typically kHz) and varying the amount of on and off time with an internal clock. Relatively simple, but very powerful. Here are a couple of tutorials to read through:

https://www.rs-online.com/designspark/pulse-width-modulation-arduino-working-explanation

https://www.tutorialspoint.com/arduino/arduino_pulse_width_modulation.htm

Most microcontrollers including Arduinos, but also Raspberry Pi’s will have some form of PWM output capability.

PWM is useful for example, say you have an LED that runs on 3V and you wish to apply a 3V signal but with a dimmer output. You can simply apply a 3V peak PWM signal with a 50% duty cycle and the LED will operate as if it is running at 1.5V, producing a dimmer light output. 50% duty cycle produces a square wave with the output ‘on’ (at 3V) for 50% of the time, and ‘off’ (0V) for the other 50% of the time.

Motors have a natural ‘filter-like’ ability to operate similarly, due to their internal inductance. You can therefore control the speed of a motor by varying the ‘duty cycle’ of a PWM signal as well! Say you have a Motor Controller with a 20V power supply attached and you wish to vary the output speed of the motor. Applying a PWM signal to the Motor Controller output with a duty cycle of 50% will cause the motor to run at half the rated full speed as if it were only connected to 10V! The PWM signal can be changed in real-time to control the motor speed.

I would recommend a Motor Controller that operates between 3-12V. A motor controller is slightly different from a motor driver, but essentially it operates by receiving a PWM signal from your Arduino, and various the supplied power output accordingly.

You can also get Motor Controllers that run off other signals like I2C… but for simplicity’s sake lets ignore that. Here is a great Motor Controller that would work for you and the relevant tutorial for it running from an Arduino:

https://wiki.dfrobot.com/2A_Motor_Shield_For_Arduino_Twin___SKU_DRI0017_#DC_Motor_Control

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HI Matt
Sorry for delayed reply, very busy with life…plus I’m a bit of a dummy in relation to this field
Thankfully your team and website is fantastic and I’ll eventually get there
I’ve already added the -Standard Gearmotor-6RPM (3-12) and its mounts to my Cart.
The Rolling Ball Sculpture I’m fabricating is very simple, just a 4mm metal fame slowly lifting marbles up a spiral tower, with all components hidden underneath
Just requiring ( I think) motor gearbox ,wiring, power source, ON/Off switch… I don’t need to change the speed
or have any LED’s , USB ports etc for no, I’m sure down the track I will

Hope this helps and you can send me more of your products to help me learn and complete my order

Again, fantastic Website and team

Regards
Sean

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Hi Sean,

That’s no worries - if you don’t require speed or direction control this makes things a heck of alot easier! You will just need a power source, motor and a switch in-between as you mentioned.

I had a look at that Standard Gearmotor (6 RPM) to check the specs. It’s 12V DC with a current draw of 95mA and a stall current of 0.5A so nothing major. Just need some parts that can handle that rating with a little overhead.

Starting with a power source - you sound like you are going the battery route. The simplest option would just be some AA batteries in a holder with an on/off switch:

AA batteries aren’t going to last forever but you’re really not drawing much power and they are very easy to source and replace. If you want something that will really last I’d try a 3S (3 cell) Lipo battery which is nominally 11.1V but charges to a bit more. You’d require a charger with a balancer so a bit more complicated but we can go down that road if you need.

Wiring - You just need some wire that can handle 0.5A max so you can just go some 22AWG solid core hook up wire which can handle 5A max:

The Switch is included in that AA battery holder above, or you can just pick another rated to handle your motor current like this:

For cool factor, I like missile launch switches! :smiley: Not needed though:

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That’s Fantastic Matt , love itI
I think I will go with your battery suggestion, this time, but when I make them for clients I want them to just be able to plug it into a normal GPO so we need to look at that next time, lets go with those 3S (3 cell) for now

The Kool switch I love to- so lets add that

Also I’m after a strong set of 3rd hands - The Hobby Creek Pana V2 looks strong, do those arms hold firm when under a bit of weight

I think your fairly across now what I need, if you could do me a huge favour , put them all together with the motor and mounts already in my cart and give me the price and we’ll proceed,

Empowering Creative People

So Grateful , Thanks for your assistance , chat real soon

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Don’t forget soldering materials if you don’t already have them! You will need to solder this all up. Some heatshrink is also handy for covering your wires and preventing shorts :smiley:

Yes the Hobby Creek Pana V2 helping hands are quite strong - they can hold a can of soft drink (see the images) so will be able to handle some weight.

As for the 3S Lipo - I would recommend Hobbyking for a 3S Lipo. Any of their Turnigy Lipos will do, so long as it is 3S. Don’t need a high C rating for this purpose so grab something cheapish like this:

Or for a smaller option try:

I’m not able to access your cart (and I wouldn’t recommend we discuss that via the forum anyway :wink:) but a quick price estimate is just a click away on those links above! Just add to cart, go to the checkout, enter your postcode, and hit estimate shipping and you’ll have a price estimate right there without having to commit to the purchase. :star_struck:

Let us know how you go with the project too.

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