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How can my motors sharpen my knives?

  1. Jan 14, 2014 #1

    I'm currently studying an engineering course at college and for this I'm required to complete a project.

    Knife sharpener.
    Two spinning cutting tools driven by individual motors.

    I'm wanting to power two small low voltage dc motors from a 230v ac supply.

    There will be one main on/off switch, a variable speed switch (most likely a variable resistor of sorts) and two roller switches that activate the mechanism. Only one roller switch will be needed to activate the motors but at times both switches will be on.

    I intending on using a phone charger like plug which will in turn plug in to the main device. A power supply unit will then power the motors.

    What I'm struggling with (I think) are the basic numbers. If I were to use 12v motors could I provide enough current from a 1000mA charging plug to get the motors going?

    I don't know what maths I need to use.


  2. jcsd
  3. Jan 14, 2014 #2


    User Avatar
    Science Advisor

    You have not described the size of the knife or the type of tool.
    You will need to find the power required to drive the cutter or grinder when it is in contact with the knife.
    Power will be a function of things like the tool and knife material, surface velocity and rate of material removal.

    You should start by looking at a copy of Machinery's Handbook. Industrial Press Inc.
    The section on machining operations, grinding processes, would be worth study.
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