[TowerTalk] Reply - KW3000 with 1/2 inch Drill Motor - Wrongassumption in responses

[Dennis Vernacchia]

Rick,

I was told by a friend who is knowledgeable about the subject that yes, the
drill converts AC to DC so
not a candidate for Pulse Width Motor Speed Controller

I need something off the shelf as I don't have time to reinvent the wheel
right now.

Will have to wait for a solution on reflector unless you come up with
something in your quest
for same thing I need.

73, Dennis N6KI


On Thu, Oct 15, 2009 at 8:13 AM, Richard (Rick) Karlquist <
richard at karlquist.com> wrote:

>
>
> Dubovsky, George wrote:
>
>> You will still lose torque with a pwm light dimmer. You will need
>> something like an variable speed drive, where you vary the drive frequency
>> and voltage simultaneously, essentially synthesizing a complete sine wave at
>> an adjustable frequency. I use them on three-phase motors on my lathe and
>> mill, but they are also available for single-phase motors. Not cheap, but
>> less than the Hole Hawg ;-)
>>
>> 73,
>>
>> geo - n4ua
>>
>
> The idea of the PWM method is that you have full torque when
> on, but are not on all the time.  You do lose horsepower, but
> not torque, AFAIK.  It's similar to pulsing the ON/OFF switch
> on the drill.  I am not sure if there is any difference between
> a PWM motor speed controller and a light dimmer.
>
> A variable frequency drive sounds like something for an AC induction
> motor.  Most drills AFAIK are AC/DC motors, for which frequency is
> obviously irrelevant.
>
> If the above is wrong, someone correct me.  I want to get a
> Hole Hawg too, as soon as I figure out how to slow it down.
>
> Rick N6RK
>