Sparkfun tinker kit ( KIT-14556) issues with driving motors "circuit 10: motor basics"

Kits
1

Hi all,

I bought the sparkfun tinker kit ( KIT-14556) to get started messing around with electronics.

https://www.sparkfun.com/products/14556

Right now the problem I’m having is that these hobby gearmotors (https://www.sparkfun.com/products/13302) stop spinning as fast over time with a very light load taped to the white, plastic shaft… Wondering if they simply break a lot (they are made in China and very cheap) or I’m running too much current through them or something?

I even corresponded with a sparkfun tech support employee named "Chris F "to figure out what was going wrong. When I paid to send in both my motors that weren’t spinning as fast, he claimed that I must have taken them apart and improperly reassembled them. He said neither the redboard or the motor driver (https://www.sparkfun.com/products/retired/13845) showed any problems in the lab when he tested them.

I never took them apart and had no reason to. He was nice enough to send to send me a new pair of motors. Unfortunately the new ones he sent me stopped spinning so fast after a while too, even though I still only had a very light weight load duct-taped to the white shaft.

Here’s what I did with the motors. I followed the tutorial to build circuit #10 documented in the link:

https://learn.sparkfun.com/tutorials/ac … tor-basics

I followed the same circuit diagram provided shown in the tutorial and used the code provided.

The main changes I made to the arduino code were that I only spin the motor forward and commented out the part where it spins backwards in the opposite direction. with a time delay of 600 ms instead of 3000 ms shown in their default code. So when the circuit is powered on, it only spins the motor and the load I attached to it in one direction.

Can anyone tell me whether these motors tend to stop spinning as fast over time on their own or if the tutorial circuit sparkfun provided needs some extra parts (e.g. a flyback diode) to avoid damaging the motors?

Thanks for your help!

P.S. I’m happy to send in pictures/videos of my circuit running the motor with the exact code I flashed to the arduino, if that would help diagnose why my motors stop spinning so fast at a PWMA of 255 once they’ve been run for more than, say, 100 hours of cumulative use.

2

It sounds like you may be wearing out the gearbox on your motors. 100 hours is an awfully long time for a toy motor with plastic gears to run.

You might consider upgrading to a motor with metal gears like [ROB-12125 running at 6 volts. As long as you keep those lubricated, they should considerably outlast the plastic geared motors that come with the Tinker Kit. Another even heavier duty option would be [ROB-15277 but you would need a 24 volt power supply to run those.](https://www.sparkfun.com/products/15277)](https://www.sparkfun.com/products/12125)

3

TS-Chris:
It sounds like you may be wearing out the gearbox on your motors. 100 hours is an awfully long time for a toy motor with plastic gears to run.

You might consider upgrading to a motor with metal gears like [ROB-12125 running at 6 volts. As long as you keep those lubricated, they should considerably outlast the plastic geared motors that come with the Tinker Kit. Another even heavier duty option would be [ROB-15277 but you would need a 24 volt power supply to run those.
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I took apart one of the Dagu motors that isn’t spinning very fast to see if the gearbox inside the plastic yellow housing looked worn down. A cursory inspection doesn’t indicate anything obvious. The gearbox system that the motor drives looks fine.

The DC electric motor itself doesn’t spin very fast. Is there a way I could figure out whether the electric motor itself or its internal gear systems are worn out?

Thank you](https://www.sparkfun.com/products/15277)](https://www.sparkfun.com/products/12125)

4

There are no gears inside the motor, but the bearings may be wearing out and that could definitely cause the motor to run slow. A little bit of penetrating oil on both motor shafts might prolong the motors life a bit. If that doesn’t work, the motor is just worn out and will need replaced.