[Jewelry making - Article 00036] - Re: [Orchid] Speed Control

[James Binnion]

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>      So many of the machines we use operate at speeds that are too
>     fast. Does anyone know where I can find a reasonably priced, new or
>     used, speed control in the 10-15 anp range? 

    Universal motors like the kind on most flexshafts are easy to
    control by just reducing the voltage to the motor this is what the
    foot control does. It is a cheap control mechanism. It is extremely
    rare to find a large universal motor that would need 10-15 amps,
    that would be a 1-2 HP motor (about the only place you find larger
    universal motors is in fans like ceiling fans and they are still in
    the 1/4 HP and smaller range). Most motors that are 1/4 HP and
    larger are induction motors and they cannot be safely speed
    controlled by changing the voltage if you try you may burn up the
    motor and start a fire. To control a induction motor you need to
    change the frequency not the voltage and the motor should have
    special windings to handle the higher heat when running at slow
    speeds (most motors are cooled by an internal fan that is on the
    rotor and if the rotor is spinning slower then there is not as much
    air flow therefore more heat) In fact with induction motors the only
    ones I know of that are speed controlled are three phase motors.
    There are large DC motors that are voltage speed controlled but they
    tend to be quite expensive because they need permanent magnets to
    make them work and these are quite costly in the size and power that
    is needed. 

    	I know that this is very long winded but the short answer is you
    can't do it unless you change the motors on most of your shop
    equipment. 

    Jim Binnion James Binnion Metal Arts Phone (360) 756-6550 Toll Free
    (877) 408 7287 Fax (360) 756-2160 http://www.mokume-gane.com
    jbin AT mokume-gane.com Member of the Better Business Bureau


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