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choosing a motor and parts.

gio_dude

Sorry about the simple questions in advance but I'm very new to motors.

 

So I wanted to make a retractable window curtain the goes up and down and coils on to its self. So what I was thinking was bluetooth or wifi feather from adafruit with their motor driver wing (https://www.adafruit.com/product/2927 ). A  motor on a rod with the curtain hanging from it.  

 

So if I'm missing something that will make this project completely fail in my face please tell me.

 

here are my questions

 

what type of motor should choose?

I've been reading a lot about stepper motor and they look promising since I can have more precision.

 

What type of torque do i need to be looking at.

I read the post about torque and need to read it a few more times to understand it all but it doesn't sound like I need a lot of torque.

 

Motor to rod connection.

I don't know terms very well and looking at 3d printers they use a coupler to attach the motor to a rod. is there a different way i should research or a better way of doing it.

 

Dual motor

I was thinking about using a motor on each side one wired in reverse is that a good idea.

 

thanks in advance

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    Hi Giovanni,

     

    It seems that your application will need a higher torque lower speed motor if you are going to directly couple the rod to the motor shaft. Since these type motors are geared down and when not powered they do not turn freely you would not be able to use one to turn the rod up and another to turn the rod down. Better to design the circuit to turn the motor either way depending on how you want to move the shade.   's suggestion of a stepper is a good one as you can precisely control the movement in either direction as well as having reasonable torque. You can make an estimate of the torque that you will need by measuring the mass of the shade material in kilograms and multiply this number by the acceleration of gravityat the surface of the Earth of 9.8 meters per second ^2. This will give you the Newtons of force that the shade will exert on a given lever. The lever in this case will be the radius of the rod that you plan to use. Let's say that your shade has 1 Kg of mass. 1Kg X 9.8m/sec^2 = 9.8 Newtons of force. Also lets assume that you are using a Rod with a diameter of 3 cm. This means that the radius of the rod is 1.5 cm. Now we have to multiply this distance (1.5 cm) by the force of 9.8 Newtons to get the approximate minimum torque needed for the motor to raise the shade. In this case 1.5 cm x 9.8 Newtons gives us a torque of 14.7 Newton centimeters. For practical purposes it would be a good idea to get a motor that can produce perhaps half again the minimal torque required.

     

    John

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  • 0

    Hi Giovanni,

     

    It seems that your application will need a higher torque lower speed motor if you are going to directly couple the rod to the motor shaft. Since these type motors are geared down and when not powered they do not turn freely you would not be able to use one to turn the rod up and another to turn the rod down. Better to design the circuit to turn the motor either way depending on how you want to move the shade.   's suggestion of a stepper is a good one as you can precisely control the movement in either direction as well as having reasonable torque. You can make an estimate of the torque that you will need by measuring the mass of the shade material in kilograms and multiply this number by the acceleration of gravityat the surface of the Earth of 9.8 meters per second ^2. This will give you the Newtons of force that the shade will exert on a given lever. The lever in this case will be the radius of the rod that you plan to use. Let's say that your shade has 1 Kg of mass. 1Kg X 9.8m/sec^2 = 9.8 Newtons of force. Also lets assume that you are using a Rod with a diameter of 3 cm. This means that the radius of the rod is 1.5 cm. Now we have to multiply this distance (1.5 cm) by the force of 9.8 Newtons to get the approximate minimum torque needed for the motor to raise the shade. In this case 1.5 cm x 9.8 Newtons gives us a torque of 14.7 Newton centimeters. For practical purposes it would be a good idea to get a motor that can produce perhaps half again the minimal torque required.

     

    John

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