Best solution for wheel used for motion and scroll wheel

I’m trying to figure out the best solution for a prototype I’m making. I need to create a wheel mechanism that can continuously rotate both directions at about 130RPM. Like a FS90R. pololu.com/product/2820 And at about that size of motor/servo.

However, I also need to use the same wheel for hand turned feedback/position control. Very similar to how a motorized volume knob works. I’m worried that I’m going to strip whatever geared motor/servo I’m using. I have a lot of technology opened in many many browser tabs, but I’m just not sure where I should be focussing.

Starting to think that separating the encoder from the motor would be best. But I’d be happy with something like pololu.com/product/2598 with a gear motor. But would the gears get stripped?

Thoughts? Help? Advice?

Thanks!

Aaron

Hello, Aaron.

We have not characterized how geabox wear might differ depending on whether the motor is driving the shaft or the shaft is driving the motor, but I suspect what you are proposing would be okay for a gearbox with a low gear ratio, like 10:1 or 30:1. Just make sure that the motor is able to coast when it is being driven by hand (i.e. the leads are electrically isolated from each other) rather than configured for braking (i.e. with leads effectively shorted together through your driver).

The encoder you mentioned is designed to be mounted on the back of our micro metal gear motors; I would specifically recommend trying it with our low-power 30:1 micro metal gearmotor. The free run speed of that motor is much higher than your target speed of 130 RPM, but you could always use the encoder feedback to run it at a steady slower speed.

If you do try it, we would be interested to hear how it works for you along with more about your project! Please let me know if you have any further questions.

-Nathan

[quote=“wiegerthefarmer”]I’m trying to figure out the best solution for a prototype I’m making. I need to create a wheel mechanism that can continuously rotate both directions at about 130RPM. Like a FS90R. pololu.com/product/2820 And at about that size of motor/servo.

However, I also need to use the same wheel for hand turned feedback/position control. Very similar to how a motorized volume knob works. I’m worried that I’m going to strip whatever geared motor/servo I’m using. I have a lot of technology opened in many many browser tabs, but I’m just not sure where I should be focussing.

Starting to think that separating the encoder from the motor would be best. But I’d be happy with something like pololu.com/product/2598 with a gear motor. But would the gears get stripped?

Thoughts? Help? Advice?

Thanks!

Aaron[/quote]

So you are using a gear motor "backwards just so that your encoder spins faster and has more resolution. A better way to do that might by to use a timing belt. Some times they also add in a weight disk to add some rotational inertia and also some dampening grease for a better feel. But maybe a cheap gear motor is the lower cost solution?

The other solution is to buy an encoder with the required resolution. They are made of a glass disk wth a couple thousand radial lines on them. Again the motor idea seems lower cost. It might work.

You might be able to remove the motor from the gearbox and attach the encoder to the “fast” end of the gearbox.