Re: Drill press and Variable Speed

Dan, it seems that your motor is a fairly common PM (permanent magnet field)-type, and therefore has no field wires/leads to be concerned with.
It should be fairly obvious that the green wire is earth ground, and is very likely connected to the motor's case/housing.

Yes, reversing the red & black connections will reverse the direction of the motor when the switch is located between the circuit board and the motor.
The only precaution is to only switch the direction when the motor is stopped (the drive circuit board output is zero).
The reversing switch that's generally used is a DPDT (six terminals) type.

Since the motor is a Leeson, and from a piece of commercial equipment, it probably has adequate cooling for being run at low speeds.
This is an important consideration when various other types of motors, intended to be run at higher operating speeds, are utilized for running shop machines at lower than (the motor's) optimum speeds.
Another consideration for the generic variety of treadmill motors is that they sometimes utilize a flywheel with fins to act as a fan to cool the motor, which is less effective at slower speeds, and that the shafts are commonly threaded to accept the flywheel, because the motor's intended use is to run in one direction only.

Generally, the only maintenance issue for a quality DC PM motor such as a Leeson would be to inspect the brushes to make sure that they're replaced before they wear out, along with cleaning out any brush dust that may accumulate in the brush holder/commutator area.
Obviously, if the motor becomes noisy, the bearings should be inspected and replaced as needed.

Other stuff..
Switches are usually rated for how much current they can switch (as in turning a device on/off).
Since the reversing switch in this instance only needs to be able to "hold" the motor current (used for changing direction, not run/stop), it doesn't really need to be rated for switching the full motor current. A quality 20A rated toggle switch would likely be adequate for reversing this motor.

The ideal method to start/stop the motor would be the treadmill's original method, which probably gradually ramps up the motor speed when it's started. This may have been a connection to the drive board that came from the treadmill's control panel, or another type of operator's switch.
Starting the motor by switching the output of the drive circuit is likely to damage the drive circuit, and should be avoided.

Many types of drives employ a safety stop method (such as the occupant falling off the treadmill), and this connection, often referred to as inhibit, could be used for an emergency stop switch. The inhibit connections are a safe way to de-energize the drive's output without risking damage to the circuit.

Any location on the drive circuit could be hot to earth ground, and the circuit should be in a protective housing to eliminate any possibility of contact with the circuit.
The AC line connections and the other circuit connections, including the start/stop switch connections, all need be insulated for safety.
Any electrical connections should be treated as potential electrocoution hazards, especially since this is being considered for a metalworking machine.
That's one reason why so many devices today have so much plastic on them.

It's creepy to see pics of home shops where drive circuit boards and other electrical devices are hung on a nail in the wall, with wires strung around to the machine.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"DanG" <dgriff23@xxxxxxxx> wrote in message news:vr4Di.108$hP1.71@xxxxxxxxxxxxxxx
engineman,

I appreciate everyone's input, but I want to clear up the reversing. The motor has red, black, green that terminate on a printed circuit board. I'm sure the circuit board's primary responsibility is to create DC and also to provide the variable input. If I understand correctly, reversing the red, black motor leads should reverse the direction. My main concern would be to not hurt the circuit board. The reversing should occur after the circuit board, and the circuit board should not be affected?

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DanG (remove the sevens)
dgriff237@xxxxxxxx





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