Router Speed Control on Drill Press?

[dkerfoot]

Just curious if anyone knows if it is OK to use one of the external router speed control boxes to adjust the speed on a DP. I am guessing that they are intended only for universal motors and wouldn't play nice with the induction motor on the DP. Correct?

I've got a 5 speed DP that goes down to 500 RPM and I was just curious if I could safely lower the speed using the router speed control box.

Thanks!

[Tom Slick]

you are correct, they only work on universal motors. you need a variable frequency drive to control the speed on an induction motor.

[phrog]

you are correct, they only work on universal motors. you need a variable frequency drive to control the speed on an induction motor.

Variable frequency drive? What's that?
Richard

[LCHIEN]

Variable frequency drive? What's that?
Richard

The speed of a induction motor is more or less tied to the AC line frequency.

So you need basically what amounts to an inverter with a variable freequncy output. Run it at 30 Hz and the motor runs at half speed.

you also need a AC to DC unit. Put it all together and you have a 60 Hz AC in to variable speed AC out or what they call a variable speed drive.
Everything has to be properly sized for the loads.

[dkerfoot]

Reaching way back to my Navy days - it is called a Variac, right?

[phrog]

The speed of a induction motor is more or less tied to the AC line frequency.

So you need basically what amounts to an inverter with a variable freequncy output. Run it at 30 Hz and the motor runs at half speed.

you also need a AC to DC unit. Put it all together and you have a 60 Hz AC in to variable speed AC out or what they call a variable speed drive.
Everything has to be properly sized for the loads.

Thanks, Loring. That's what I love about this site - I get an education every time I log in. Again, thanks.
Richard

[jziegler]

Reaching way back to my Navy days - it is called a Variac, right?

No, a variac is a variable transformer. It varies the output voltage. An induction motor speed doesn't vary based on voltage (much), but frequency. Now, a variac is fine to control the brightness of a lightbulb, might work on a universal motor, but would not work on an induction motor.

Jim