12V DC stepper application

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rdsanders
 
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12V DC stepper application

Post by rdsanders »

We need to build a simple 12V DC controlled lever position stepper.
The lever moves in a simple forward and backward operation.
The lever is used to place a motorcycle differential in a forward or reverse position.
We us a 12V DC motorcycle battery to control all electronics.
Is it possible to build a control system using your components?
If so, which components will we need?
Can we control the travel of the lever with a stepper motor?

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adafruit_support_bill
 
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Re: 12V DC stepper application

Post by adafruit_support_bill »

The answer is 'probably'. But you will need to understand the mechanical requirements as well as the electrical:
How much force is required to move the lever?
How far does it have to move?
How fast does it need to move?

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

The force required to move the lever is 250N. cm
The lever moves about 1.5 inch on an axis
Speed is not an issue, just need to move it into forward and reverse

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Re: 12V DC stepper application

Post by adafruit_support_bill »

N/cm is a unit of torque. How long is the lever?
If you divide 250 by the length of the lever in cm, you will get the force in newtons required at the end of the lever.

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

The lever is 2.5 inches (6.35 cm)
Force required 39.4 newtons

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Re: 12V DC stepper application

Post by adafruit_support_bill »

You could use a stepper motor, but you would still probably want some limit switches. An alternative would be to use a geared DC motor. In either case, if speed is not critical, I would suggest using a lead-screw or ball-screw for the linear motion.

You could control either type of motor with an Arduino and our motor shield. You could use our #324 stepper motor, or www.pololu.com has a number of 12v geared DC motors that would work as well.

Limit switches could be done in a number of ways, depending on what makes sense mechanically. You could mount simple contact switches at the extremes of travel. Or you could use magnets and a hall-effect sensor.

McMaster Carr is a good source for other mechanical parts such as lead-screws.

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

Thank you, I may just use a standard DC motor with limit switches.
We can account for the "coast" of the motor by using limit switches and introducing an artificial stop.
We can also use a spring to apply a constant force to hold the lever in place.
We just have to ensure that the motor can overcome the applied force of the spring to move the lever in reverse.

Thank you very much,
Robert

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Re: 12V DC stepper application

Post by adafruit_support_bill »

Geared motors tend to 'coast' less. And with a lead-screw or ball-screw, it will hold its position very well. There would be no need for springs.

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

Could these be used with limit switches and a simple reverse polarity switch for forward an reverse?
Or do we also need the motor controller and motor driver?

Thanks

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Re: 12V DC stepper application

Post by adafruit_support_bill »

Yes. If you don't need speed control (doesn't sound so) you could wire up a mechanical switch to reverse the direction.

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

Do you have a suggestion for a geared motor that we can use?

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Re: 12V DC stepper application

Post by adafruit_support_bill »

Something like this, mated to a lead-screw should work: http://www.pololu.com/product/1103

rdsanders
 
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Re: 12V DC stepper application

Post by rdsanders »

Thank you, I will try this!

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Re: 12V DC stepper application

Post by rdsanders »

Do you also have a suggestion where we can purchase lead screw assemblies?
We don't need large grade metal for this project, maybe m6, m8 or m10

Thanks,
Robert

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Re: 12V DC stepper application

Post by adafruit_support_bill »

McMaster Carr is a good source for all things mechanical: www.mcmaster.com

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