Slowing down a clothes dryer


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  1. #1
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    Default Slowing down a clothes dryer

    Hi folks,

    I need to slow down a conventional 220V clothes dryer to 1 rev/sec or a bit less. Is it possible to do that to these types of motors?

    My first thought was PWM, but this is most likely a 1/2HP AC motor (total guess).

    Only says Frigidaire on the front, nothing on the sides or rear except generic DON'T PEE ON 220V wanring label.

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    EDIT: oh boy, looks grim:

    https://www.reddit.com/r/AskEngineer...m_of_ac_12_hp/
    Last edited by Demon; - 3rd May 2020 at 20:50.
    Not as dumb as yesterday, but stupider than tomorrow!

  2. #2
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    Default Re: Slowing down a clothes dryer

    Since you don't know what sort of motor is controlling your drum motor, I would guess it's just a basic AC induction motor. That being said, the speed of the motor is based on the AC input frequency; 50/60 Hz. Due to the nature of conventional AC motors, this is not negotiable.

    If you are willing to swap to a different electric motor, you could choose a multitude of DC options (Stepper, BLCD; which would require an AC/DC converter) or retrofit & learn the intricacies of the IMP AC motor (which still requires a swap).

    Surely you are going to tell me that your appliance has a slow speed and faster speed built into the electronics already. If that's the case, look at the schematic that controls it (I've found schematics for every appliance I have had to work on that lives in my home on the internet). You may find clues there.

    Bottom line, controlling speed with an AC motor involves WAY more than with a DC motor. If you could provide more information, those in the know may be able to zero you in on a more specific plan of action.

  3. #3
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    Default Re: Slowing down a clothes dryer

    The drum of a clothes dryer is belt driven.
    If you are looking for a slower, but fixed, rotational speed it might be easier to reduce the diameter of the pulley on the motor to achieve the desired result?

    Cheers
    Barry

  4. #4
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    Default Re: Slowing down a clothes dryer

    there is always something like this
    https://www.jaycar.com.au/speed-cont...otors/p/KC5509

    there was an article in silicon chip mag years and years {ancient historical times when everything was not made in china} ago that described and designed the kit
    This is more entertaining than Free to Air TV

  5. #5
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    Default Re: Slowing down a clothes dryer

    Thanks folks.

    I've since learned of a thing called a centrifugal clutch which is going to interfere with what I want.

    Thanks for your advice. I'll must likely take out the motor, reduce the rotation using several pulleys, and use a much smaller "tub" for my use.

    Robert
    Not as dumb as yesterday, but stupider than tomorrow!

  6. #6
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    Default Re: Slowing down a clothes dryer

    Can you weld? If yes you can add an idler pulley to slow the rotation. You'd still have to do the math as to what size pulleys you'll need but it could be done. I don't know if you'd be able to do it in one step because of the size of the pulleys.

    Another option would be to find a suitable washer with a DC motor and refit into your dryer. Then you can worry about PWM. A treadmill motor would be perfect as the control is already done for you. Mounting may be a challenge but refer to first question.

    If you were closer to Las Vegas, NV I could fix you up.

  7. #7

    Default Re: Slowing down a clothes dryer

    consider that the BLOWER runs off same motor/belt........ can't blow air when slowing motor ???

  8. #8
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    Default Re: Slowing down a clothes dryer

    Quote Originally Posted by AvionicsMaster1 View Post
    Can you weld?
    I can.


    Quote Originally Posted by AvionicsMaster1 View Post
    If yes you can add an idler pulley to slow the rotation. You'd still have to do the math as to what size pulleys you'll need but it could be done. I don't know if you'd be able to do it in one step because of the size of the pulleys.
    I thought of that, but buying pulleys, shafts, bearings and metal will quickly pass $50. Add the cost of that 4 prong 220V receptacle and I'm at $100 with taxes.


    Quote Originally Posted by AvionicsMaster1 View Post
    Another option would be to find a suitable washer with a DC motor and refit into your dryer. Then you can worry about PWM.
    I thought of a washer motor. I have one on hand and they operate on 110V so no fancy power plug required. I'm pretty sure this will be the same AC design.


    Quote Originally Posted by AvionicsMaster1 View Post
    A treadmill motor would be perfect as the control is already done for you. Mounting may be a challenge but refer to first question.
    Most definitely, powerful and 110V, but don't have one.


    Quote Originally Posted by AvionicsMaster1 View Post
    If you were closer to Las Vegas, NV I could fix you up.
    I really would have liked that.


    My primary goal was for this project to be dirt cheap. I can get a new case cleaner for under $100. It's not large capacity, but it would do for my needs.
    Not as dumb as yesterday, but stupider than tomorrow!

  9. #9
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    Default Re: Slowing down a clothes dryer

    Quote Originally Posted by amgen View Post
    consider that the BLOWER runs off same motor/belt........ can't blow air when slowing motor ???
    Pretty sure this design runs only the tub off the motor. The blower is basic electric motor and fan.

    And I don't need to blow air, in fact, I don't want to because of the dust from tumbling media.

    I wanted a very slow turning tub to do this (start at 1:18):

    Not as dumb as yesterday, but stupider than tomorrow!

  10. #10
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    Default Re: Slowing down a clothes dryer

    OK. I know this may sound stupid but how fast will the drum turn if you took the pulley off the motor shaft? There may be enough grab to turn the drum belt from the shaft alone but you should significantly slow the drum down. I'm guessing the pulley is about 3" in diameter and the shaft maybe 1/2" at most. If that works you can do something to the shaft to increase the grab of the belt. It's a hail mary but then again why not?

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