DC Motor; Variable Speed Controller DIY Project. -- HELP!

Discussion in 'The Projects Forum' started by Theory13, Aug 6, 2013.

  1. Theory13

    Thread Starter New Member

    Aug 6, 2013
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    Hello,
    I am definitely over my head in electronics. But i am willing to listen and learn!

    I'm working on a project to build a 'Roto-Molder', for casting hollow resin parts for an art project. Here is a video from YouTube showing the (hopeful) end result. http://youtu.be/xcdkDKkiBeU

    That machine is beautiful, but over kill for me. I'm trying to make a wooden version of it. (more in my skill set).

    I have acquired a motor for the project (from a treadmill). It is a Pacific Scientific motor ( PWM 3636-5250-7 ) , 2.3 HP, RPM 3590, Volts 124DC 16.8AMP
    Here is a picture of it:
    [​IMG]

    I'm looking to be able to adjust the speed of the rotation for this motor.
    I'm assuming the Red/Black wires are for powering the motor.

    I'm not sure what the lead in this picture is for:
    [​IMG]
    It seems to be 3 wires that connect to one metal plate that is bolted/screwed to the motor. Do you think i can remove this part??

    would it be possible for me to purchase a Treadmill DC Motor Controller from ebay like this one: http://r.ebay.com/2M0Nax

    and put a 5k POT on it to adjust the speed of rotation? If i were to use a 1k, or a 10k PTO... would i get more control of the motor going slow?

    I am definitely not a master at reading electronic diagrams, but it looks like with the Treadmill DC Motor Controller, i would just need to connect a power cord, and then a POT, and then wire the red/black motor wires.... if i were to do this, would I be all set?

    Am i correct in this thinking?

    Would anyone have any other simple solutions to controlling the speed of this motor? (or is this motor not even capable of achieving my desired results?)

    ____

    as an alternative solution, could i just connect the motor (red/black wires) to a power cable, and then connect a 'Step Less Speed Controller' like this from amazon? http://amzn.com/B000HQAVNI

    also as an option, i was thinking of putting some type of timer into this system... maybe some type of wall wart that would turn off the machine after 20-30 minutes. Kind of like how some jacuzzi's have a rotating/timed kill switch?


    Thank you, Thank you, Thank you for any advice or suggestions on this project!
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    What size of 'rotating' machine are you building?

    2+ Horsepower could turn a large standing cement mixer easily.(500-1000 lbs)
     
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  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    a smaller(and cheap) DC motor, say of 12 or 24 volts would be good for a small project like you describe. Google 'gear motors' for a list of reading and visual aids.


    some motors are 110 VAC driven, and are low power, high torque, and slow RPM. Perfect for rotating molds
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    The component in the last photo, that you were asking about, is an opto-interupter. It probably was used in the original controller as a speed feedback. To keep the speed set at the RPM set on the controller. Probably not needed for what your doing.
     
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  5. Theory13

    Thread Starter New Member

    Aug 6, 2013
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    Hi Kermit2,
    wow.... i didn't know a 2hp motor could be that strong. I probably need it to turn under 150 lbs. (maybe under 100 lbs.)
    I figured that this motor would be able to handle it. Can't it still work for this purpose? (granted it sounds like it's got plenty of power...)

    (thanks so much for your reply!)
     
  6. Theory13

    Thread Starter New Member

    Aug 6, 2013
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    Hey Kermit.
    I'm trying to keep costs as low as i can on this project (not your problem, I understand). I'd really, really like to -NOT- buy another motor.

    Do you think that this Pacific Scientific motor would possibly work?
     
  7. Theory13

    Thread Starter New Member

    Aug 6, 2013
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    Awesome Shortbus.
    thanks for that information. I've learned something today! whoohoo!
    I'm happy to be able to take it off!

    Cheers!
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Search ebay for KB/Baldor DC motor controllers, they come in the simpler SCR type control or PWM they generally are a better choice than the actual T.M. controller.
    And run direct off of 120vac.
    Max.
     
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  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    You are going to use gear reduction in this project aren't you? The 2HP rating is at the full motor RPM, it drops off as the speed is slowed down electrically. V-belts and pulleys are a inexpensive way to do it, look at the way most machinery is done.

    Figure what the optimum top speed should be. Then gear for that. Then your controller can be used to adjust slower by a small amount if needed.
     
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  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    BTW, if you notice in the listing description for the T.M. controller on ebay, it mentions PWM control, this usually refers to the control method input, not the motor control, it is easier to simply use a 5k pot with the KB/Baldor one and usually can be had cheaper.
    They can be had with full enclosure, pot. switch etc or bare bones chassis model.
    Max.
     
    Last edited: Aug 7, 2013
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  11. strantor

    AAC Fanatic!

    Oct 3, 2010
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    My first suggestion would be a KB drive too. I recommend them to my customers, when their old giant <2HP drives break down - much cheaper to replace with a KB than send in for repair. The $75-$100 is usually pocket lint to them. But in OP's case/budget, I see the MC-60 controller selling for 1/2-1/3 the cost of the KB drives. And if you look at second picture of the ebay listing, it shows the proper terminals for potentiometer connection, and they offer to include the pot for free when you "buy it now." I suspect PWM refers to the output.

    To the OP, a word of caution. If you go with the MC60 or the KB drive, both have non-isolated speed signals. You may think "the speed signal is only 0-10V, so no chance of it shocking me" but that 0-10V signal is actually floating tens of volts above ground and could potentially fatally shock you. Make sure you guard the potentiometer terminals inside an enclosure or something so there is no chance of contacting them. If you let the speed pot wires come in contact with anything, it could kill the board.

    Additionally, some things I glanced at while googling led to believe that the aluminum case/heat sink of the MC60 may also be floating. There was guidance not to ground the heat sink. If this is true, you may need to mount it in a plastic enclosure or stand it off from a metal panel with rubber feet and secure it with nylon nuts.
     
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  12. Theory13

    Thread Starter New Member

    Aug 6, 2013
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    I wanted to thank everybody for all their help and advice on this topic.
    .
    I got a hold of the electrical engineer today that was in charge of these motors for the treadmill company that they were created for, and he clearly knew the motor inside and out. He was extremely helpful, and went out of his way trying to help me with a solution to this project.
    .
    I basically came away realizing that this motor is not the right one for this project.
    The cost of acquiring the controller was going to be a problem (possibly over $500), and even then, i was going to need to run a series of pulleys to convert the timing of the power (rpm's) of the motor to my requirements.
    .
    I've ended up purchasing a different motor that i think is more inline with what i'm needing. It's a turnkey solution for me that is already assembled. http://wondermotor.com/Rotisserie_motor.html
    It was more than I was hoping to pay, but all other solutions from companies like grainger, mcmaster carr, and others were proposing orders in the +$500 range. so at just under $200 for motor, taxes, & shipping ($195.05 total out the door).... this seemed like a solution for me.
    .
    my budget originally was in the $40-50 range --- but researching and pairing up controllers and motors was becoming time consuming (for me/learning as i went; 5 solid days so far, with no results), and i didn't feel confident solving my problem in this way.
    .
    Again, I thank you for all the advice that was shared. I appreciate what I learned through all of this. Clearly this is a group of good and knowledgeable people, and look forward to learning more from you all on these forums. Cheers!
     
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