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Hi from Jenny and stepper motor questions


jenny2
(@jenny2)
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Hi guys and gals,

I am a high school (11-12 grades mostly) science and occasionally tech teacher.

I have used the arduino uno in some student and personal projects in the past. On the other hand I know nothing about stepper motors which were suggested to me while looking at a recent project idea.

That is how I came across Bill's nice videos on interfacing arduinos and stepper motors and would like to ask for suggestions/advice from the knowledgeable folks in this forum.

I need help designing a system that moves a chain vertically or horizontally at a given frequency

Some details:

  • The chain is a thin stainless steel chain made of beads of diameter about 2.4 mm, and interbead spacing of about 3.4 mm and with length from a few centimeters up to about 1 meter (100 cm). These chains are sometimes called ball chains.
  • I would like to move the upper end of the chain with a motor either precisely vertically or precisely horizontally.
  • The motion will be typically an oscillation with frequencies ranging from less than 1 Hz to up to 8 Hz and amplitudes ranging from 1cm to 5 cm.
  • The motion needs to be controlled so that for example the amplitude is fixed and the frequency is changed.
  • The amplitude can change in small amounts for example 1.3 cm, 1.4 cm, 2.0 cm, etc.
  • The frequency can be changed from 1 Hz to 1.4 Hz, 1.8 Hz, etc.

I need help with selecting a motor that can be controlled by an arduino and work in the ranges of frequency and amplitude above.

While talking a while back with a student's dad he suggested that for the vertical motion 

the setup could be a wall-mounted bracket which holds a

stepper motor and a linear translation stage. The chain would then be driven by vertically oscillating its upper end via a wheel attached to the translation stage and to the motor.

I got lost as I wasnt familiar with stepper motors and linear stages and I couldnt understand how to go about it.

Any ideas/suggestions on how to go about it, where/what to look for, any other pointer would be most appreciated.

Thanks!!

 

This topic was modified 11 months ago 2 times by jenny2

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frogandtoad
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Posted by: @jenny2

Hi guys and gals,

I am a high school (11-12 grades mostly) science and occasionally tech teacher.

I have used the arduino uno in some student and personal projects in the past. On the other hand I know nothing about stepper motors which were suggested to me while looking at a recent project idea.

That is how I came across Bill's nice videos on interfacing arduinos and stepper motors and would like to ask for suggestions/advice from the knowledgeable folks in this forum.

I need help designing a system that moves a chain vertically or horizontally at a given frequency

Some details:

  • The chain is a thin stainless steel chain made of beads of diameter about 2.4 mm, and interbead spacing of about 3.4 mm and with length from a few centimeters up to about 1 meter (100 cm). These chains are sometimes called ball chains.
  • I would like to move the upper end of the chain with a motor either precisely vertically or precisely horizontally.
  • The motion will be typically an oscillation with frequencies ranging from less than 1 Hz to up to 8 Hz and amplitudes ranging from 1cm to 5 cm.
  • The motion needs to be controlled so that for example the amplitude is fixed and the frequency is changed.
  • The amplitude can change in small amounts for example 1.3 cm, 1.4 cm, 2.0 cm, etc.
  • The frequency can be changed from 1 Hz to 1.4 Hz, 1.8 Hz, etc.

I need help with selecting a motor that can be controlled by an arduino and work in the ranges of frequency and amplitude above.

While talking a while back with a student's dad he suggested that for the vertical motion 

the setup could be a wall-mounted bracket which holds a

stepper motor and a linear translation stage. The chain would then be driven by vertically oscillating its upper end via a wheel attached to the translation stage and to the motor.

I got lost as I wasnt familiar with stepper motors and linear stages and I couldnt understand how to go about it.

Any ideas/suggestions on how to go about it, where/what to look for, any other pointer would be most appreciated.

Thanks!!

Sorry, but I'm a little confused by your comments.
What exactly is the upper end, and what does it mean to move it precisely vertically or horizontally?

I'm even more confused with your use of electronics terminology in a mechanical context 🙂

Do you have any pictures of the chain, or any sketches, etc...?
Perhaps if you can better explain what you're trying to build, we could offer some ideas of how to go about it.

Cheers.


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robotBuilder
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I am also confused as to the requirements.

I assume this is the type of chain being referenced?  They are also used to open and close window blinds.

ballChain

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jenny2
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@frogandtoad, @robotbuilder Yes the chain is just like the one in the picture by @robotbuilder.

This is another one for sale on Amazon for example (used just for illustration)

https://www.amazon.com/gp/product/B0191XEVCO/ref=ox_sc_saved_title_2?smid=A334SR2G74CMSV&psc=1

I mean I would like to move (shake) a piece of this type of chain either up and down (not sideways) or left and right (not up and down). 

A motor or something attached to a motor would need to attach to one end of this chain and then the motor would do the shaking at a given frequency and amplitude.

For example if moving the chain up and down, the top of the chain would hang/attach to a nail or some kind of holder and the motor would then move that holder up and down.

Let me know if this is not clear and thanks for the interest!


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jenny2
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Just to add if moving the chain left/right, the chain would hang from a hook and the hook would then be moved by the motor.

 


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robotBuilder
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@jenny2

So is this some kind of standing wave experiment?

https://physics.csuchico.edu/ayars/427/labs/chain.shtml

 

 

 


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jenny2
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@frogandtoad, @robotbuilder Yes the chain is just like the one in the picture by @robotbuilder.

This is another one for sale on Amazon for example (used just for illustration)

I mean I would like to move (shake) a piece of this type of chain either up and down (not sideways) or left and right (not up and down). 

A motor or something attached to a motor would need to attach to one end of this chain and then the motor would do the shaking at a given frequency and amplitude.

For example if moving the chain up and down, the top of the chain would hang/attach to a nail or some kind of holder and the motor would then move that holder up and down.

Just to add if moving the chain left/right, the chain would hang from a hook and the hook would then be moved by the motor.

@robotBuilder no not quite a standing wave experiment. Think of it as you pick the chain with one hand and you move it/shake it up and down or left right. But with the hand I cant control the frequency or amplitude so I need the motor to do the shaking. 

Let me know if this is not clear and thanks for the interest!

This post was modified 11 months ago by jenny2

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jker
 jker
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If I'm understanding correctly, you want to convert rotational motion to linear motion.

Generally speaking this is done either through a camming mechanism (an egg-shaped thing stuck on a motor shaft pushes a spring-loaded slider away as it rotates), or a crank & slider mechanism.

You need a slider mechanism that will hold the end of your chain in some form of track, attached via a solid rod to a crank attached to the motor shaft. Adjusting the crank length adjusts the amplitude, adjusting the motor speed changes the frequency.

Wikipedia has a few interesting diagrams: https://en.wikipedia.org/wiki/Slider-crank_linkage

"A resistor makes a lightbulb and a capacitor makes an explosion when connected wrong"
"There are two types of electrical engineers, those intentionally making antennas and those accidentally doing so."


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frogandtoad
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@jenny2

Posted by: @jenny2

Think of it as you pick the chain with one hand and you move it/shake it up and down or left right. But with the hand I cant control the frequency or amplitude so I need the motor to do the shaking. 

OK, but isn't that exactly what the motor/contraption is actually controlling in the example video from @robotBuilder?


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frogandtoad
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@jker

Posted by: @jker

If I'm understanding correctly, you want to convert rotational motion to linear motion.

Likewise my thoughts too, but as per my reply, isn't that actually what the video from @robotBuilder demonstrates?


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robotBuilder
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@jenny2

What about a spring loaded solenoid?  Feed it the frequency and amplitude you want from an oscillating power source, as in the video, controlled by two POTS.  A speaker is just a membrane being vibrated by a solenoid.

 

  


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frogandtoad
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@robotBuilder

Posted by: @robotbuilder

@jenny2

What about a spring loaded solenoid?  Feed it the frequency and amplitude you want from an oscillating power source, as in the video, controlled by two POTS.  A speaker is just a membrane being vibrated by a solenoid.

Indeed, it appears to be of that nature in the video you posted.
You were discussing LC circuits recently... perhaps that could be a part of it's design?

Cheers.


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jenny2
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@jker You are right. Somebody suggested a linear stage

https://en.wikipedia.org/wiki/Linear_stage to convert the rotations of a stepper motor since all I want is motion in one direction (up and down or left-right).

This post was modified 11 months ago by jenny2

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jenny2
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@frogandtoad The video shows a chain tied at both ends. In my case only the top end is connected to the motor and the chain is hanging vertically always. So maybe I could adapt what the video does to a stretched string but not sure how.


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jenny2
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Posted by: @robotbuilder

@jenny2

What about a spring loaded solenoid?  Feed it the frequency and amplitude you want from an oscillating power source, as in the video, controlled by two POTS.  A speaker is just a membrane being vibrated by a solenoid.

 

  

The amplitude could go up to 5cm so a bit large and depending on the length of the chain whatever moves the chain might need a bit of power.


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