Rapid fire polarity switch

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  #1  
Old 03-05-15, 06:14 PM
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Rapid fire polarity switch

Hello all, i am very very new here so if im posting in the wrong area, i am sorry.
I want to make an electronic motor change directions at a very high speed. I understand that switching the polarity of the wires will make the motor rotate in the opposite direction, but how would i switch the polarity at an extremely fast speed?
Thanks in advance
 

Last edited by ray2047; 03-05-15 at 07:44 PM. Reason: Add menigful title.
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  #2  
Old 03-05-15, 06:18 PM
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Switching direction while at high speed sounds like a bad idea that would lead to potential for lots of damage. I would think you need a neutral position and to let the motor slow between forward and reverse.
 
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Old 03-05-15, 06:21 PM
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If it is an AC motor, it has no "polarity" and switching leads won't make it run in reverse., except in three phase. DC motor, yes. High speed reversal won't happen with a motor spinning. It will most likely have to be done with a fluid type drive. Tell us what you are trying to accomplish. Oh, welcome to the forums.
 
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Old 03-05-15, 07:29 PM
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What RPM do you need this to run?
How much torque.
I like Chandlers idea, picture how a Z turn lawn mower works.
They have been using the same principle on Tug boats for many years.
 
  #5  
Old 03-05-15, 07:35 PM
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Rapid fire polarity switch (Need help)

Basically i want to figure out a way to make a polarity switch change polarity at adjustable speeds. For example, make it so the polarity gets switched about twice every second, or 5 times every second (But not having to manually switch it that many times per second)

Is it doable? If so, How??!?!?

PLEASE HELP ME
 
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Old 03-05-15, 07:42 PM
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I have merged your two threads.

Please explain what you are trying to do. With that information we will better be able to answer your question.
 
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Old 03-05-15, 08:24 PM
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Okay basicallly i am trying to create a Ram that will push forwards and then retract backwards and do that over and over at a very high speed. Its not a very big ram or anything... Just a few inches
 
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Old 03-05-15, 08:43 PM
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The motor doesn't have to change rotation. A simple mechanical linkage will do it. Think crankshaft. The motor turns the crank and the crank moves the ram up and down.
 
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Old 03-05-15, 09:20 PM
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Brilliant idea! For some reason, i tend to imagine things much more complicated than they need to be in order to work. The crankshaft idea does seem like it would work, but is there a way i can make it so it Extends and Retracts the ram completely vertically? (Or completely Horizontally if i turn the apparatus on its side) I dont want any crookedness......
 
  #10  
Old 03-05-15, 10:26 PM
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Articulated connecting rod in guides.

Don't laugh. That's as good as I can draw.

Attachment 47593
 

Last edited by ray2047; 03-05-15 at 10:42 PM.
  #11  
Old 03-06-15, 06:22 AM
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How about one of these?

 
  #12  
Old 03-06-15, 08:35 AM
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Yeah! Exactly like the saw on that. In, out, in, out. But, WHAT IS GOING ON INSIDE OF THAT SAW TO MAKE IT WORK THAT WAY?!
 
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Old 03-06-15, 08:38 AM
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When i click the link for the attachment, it says its an invalid link. Im almost CERTAIN i know what your saying though. Thank everyone for their help, but i think this idea right here from Ray is going to be the one i use. However, i have one more idea. The motor has a wheel on it. the wheel has a little thing sticking out of it. The ram will be spring loaded... The wheel's thing hits it and pulls it down and eventually releases it, sending the ram flying (Via the spring)

Would the Articulated connecting rods idea be easier to make, or would the spring loaded ram be easier to make?
 
  #14  
Old 03-06-15, 09:25 AM
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Ah, yes a recyprocating saw! IT works in the exact same principle as Ray has stated! Okay i see what everybody means, and that will definately work.

This has been my first experience on these forums, and it was definately a good one! Thanks everyone for trying to help me! I finally have what i need
 
  #15  
Old 03-06-15, 09:28 AM
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After all of this, my rapid fire polarity switch idea sure does seem pretty far fetched and overly complex! Pretty funny....
 
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Old 03-06-15, 09:32 AM
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Every innovator has blinders. When Edison was working on the light bulb he accidentally discovered the vacuum tube but discarded it as useless. It took another inventor to rediscover it and base the whole new field of electronics on it.
 
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Old 03-06-15, 09:51 AM
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Yeah... Crazy. Im going to get started working on the prototype ASAP.. The prototype will probably just be made from Wood. (Aside from the motor)
Again, i cannot thank you enough.
 
  #18  
Old 03-06-15, 11:07 AM
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This isn't how a reciprocating saw works, but this is a tried-n-true flywheel piston design dating back to early steam engines or beyond. It turns a spinning force into a reciprocating linear force (or the other way around).
 
  #19  
Old 03-06-15, 06:18 PM
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Yeah. I already figured THAT out from this video: https://youtube.com/watch?v=4yqQl97s0ZQ
 
  #20  
Old 03-07-15, 11:37 AM
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The prototype is almost finished
Its pretty Rough, but hey, it works. My dad thinks its not going to work xD BUT IT ALREADY DOES WORK!
 
  #21  
Old 03-07-15, 11:52 AM
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Glad we were able to put you on the right path. Could you tell the purpose of the machine your building?
 
  #22  
Old 03-07-15, 10:37 PM
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Oh sure. Its kind of childish, really. But what can i say, i am 15 afterall.
ANYWAY, its a rapid fire button presser. You could attach it to any game controller, or a computer mouse.
I completed the prototype. WAY TO BIG! Im building prototype #2 right now. The flywheel is a penny! Perfect size! Im using Solder to attach parts lol
 
  #23  
Old 03-07-15, 11:15 PM
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ANYWAY, its a rapid fire button presser. You could attach it to any game controller, or a computer mouse.
Had I known I would have suggested a different solution, a solenoid.
 
  #24  
Old 03-10-15, 07:17 PM
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Eh... Too late. I already completed the first prototype, and prototype #2 is about 50% finished. Prototype 2 is much smaller, The flywheel is a Penny!
 
  #25  
Old 03-10-15, 08:47 PM
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Sounds good.

.
 
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