Any Electrical Engineers Out There?

[MBG]

I going to permanently mount a Milwaukee 5625 router in a table. I really like the router remote speed/power set-up shown below:

http://www.jessem.com/new_products.htm

With a lift this would eliminate the need to access the router from below. Only problem is this router/control costs more than twice the price of the router. Is there a way to dig into the router and move the speed pot to a remote location?


Thanks,

Mike

[LCHIEN]

I going to permanently mount a Milwaukee 5625 router in a table. I really like the router remote speed/power set-up shown below:

http://www.jessem.com/new_products.htm

With a lift this would eliminate the need to access the router from below. Only problem is this router/control costs more than twice the price of the router. Is there a way to dig into the router and move the speed pot to a remote location?


Thanks,

Mike

Probably the speed pot is part of a circuit board, you hardly ever see discreet pots anymore in quantity-produced electronics due to the labor it tkaes to wire it up vs soldering it into a board. I'll take better than even odds there's one circle-shaped circuit board in the router motor body attached to the speed pot in the end of the motor housing.

You could disassemble the router, move the board to the side of the table and splice some new wires from the board to the motor. there may be several wires involved.

[MBG]

Thanks Loring - I did see one this weekend and there are 5 conductors in the line from the remote speed control unit to the router.

[LCHIEN]

yeah, I'm thinking that there may be a speed/RPM sensor feedback because virtually all the elecronic VS controls reputedly maintain the speed under load; they would have to kow the speed to do that. That's why so many wires.

Incidentally that's why a router with built-in VS is better than a fixed speed router with an external speed control, is better. Also one reason why an external speed control can't be used with a router that has internal VS control (The internal controller will try and maintain speed despite the reduced power being fed by the external controller.)

[Andrew Benedetto]

Loring, how does the circuit maintain the speed? Is it based on amp draw or measure rpm like an ABS sensor does on a car?

[sacherjj]

It uses the speed sensor to determine what power is given to the motor. When the load increases, the circuit detects a reduction on speed and ups the power given to the motor. When the motor spins faster than desired, it cuts the power back. So, I guess to answer your question, by speed.

[LCHIEN]

It uses the speed sensor to determine what power is given to the motor. When the load increases, the circuit detects a reduction on speed and ups the power given to the motor. When the motor spins faster than desired, it cuts the power back. So, I guess to answer your question, by speed.

yep. that's it.

[Andrew Benedetto]

What mechanism/sensor type measures the speed? I quess that is my question. You said load, so is the circuit measuring amp draw changes by the circuit based on the initial start setting with out a sensor measuring speed of the motor?

[LCHIEN]

What mechanism/sensor type measures the speed? I quess that is my question. You said load, so is the circuit measuring amp draw changes by the circuit based on the initial start setting with out a sensor measuring speed of the motor?

offhand, my guess is that they have a magnet/sensor or an optical LED/reflector/sensor where the magnet or the reflector are on the moving part of the motor and the sensor arranged to issue one pulse per revolution. The circuit would determine if the pulse rate were above or below the setting and decrease or increase the PWM respectively to servo the motor speed. PWM is a method of controlling average voltage.
At startup there would be no pulses so he speed detector would say "low" and the PWM increased to maximum output until the speed reached the set point. This is simplified greatly, there would be some filters and other stuff to prevent overshoot and oscillations etc.