Smoked my 8520 Mill motor today CRAP!

Yep, glad it was only the start cap. If you listen to the motor, you will hear when it kicks out of run and goes to start. There's a clicking as the centrifigul switch kicks in and out. Try to listen for when you are overloading it. Keep that machine well oiled. 220 also reduces heat to the motor, since you have more voltage, and less AMPS (heat).
Yep, he even told me, "There is nothing wrong with this motor, winding is good, bearings are good, you should get some life out of it yet." I took some more cuts on the rail and it didn't even get warm. It never even though about bogging down either. I'm happy about it, BIG TIME!
 
Yep, glad it was only the start cap. If you listen to the motor, you will hear when it kicks out of run and goes to start. There's a clicking as the centrifigul switch kicks in and out. Try to listen for when you are overloading it. Keep that machine well oiled. 220 also reduces heat to the motor, since you have more voltage, and less AMPS (heat).
No problem with oil. I'm a believer in oil. Oil is cheap, parts are expensive. I have oil dripping out of every nook and cranny. ;) In fact, if I'm running it for any length of time I shut things down and re oil the bearings. (just in case) Yep, I'm no stranger to the power of oil.
 
So what did he show you ??? What's this secret?
 
My 8520 had a bad motor when I got it.
I followed Billy G's example and replaced mine with a 1 HP motor from Grizzly, $190 plus shipping. http://www.grizzly.com/search?q=(motor)+AND+(brand:Grizzly)+AND+(category:Motors)
Bolted right on no mods required, but did require buying a different belt due to larger motor diameter.
I went ahead and replaced both belt since I had it apart. Took a 1/2" x 24" and a 1/2" x 48".
Might consider replacing the motor mounts too, I'll see if I can find where I got them, they're cheap and made a world of difference in vibrations at high RPM..
 
So what did he show you ??? What's this secret?
To my untrained novice eyes, he hooked it up to 220, hit the switch and the motor had so much torque just sitting there, it jumped 4 inches off the bench (on 110 it just sat there and ran). That's what the show was. Like I said, to many of you, this is second hand knowledge but to me, it was enlightening . I ran the line, the mill is 220 now! :grin:
 
My 8520 had a bad motor when I got it.
I followed Billy G's example and replaced mine with a 1 HP motor from Grizzly, $190 plus shipping. http://www.grizzly.com/search?q=(motor)+AND+(brand:Grizzly)+AND+(category:Motors)
Bolted right on no mods required, but did require buying a different belt due to larger motor diameter.
I went ahead and replaced both belt since I had it apart. Took a 1/2" x 24" and a 1/2" x 48".
Might consider replacing the motor mounts too, I'll see if I can find where I got them, they're cheap and made a world of difference in vibrations at high RPM..

Thanks but I don't have mounts on mine. It's bolted right to the cast. I've had no problems. However, please post a link anyway in case I have problems in the future. Thanks.
 
A 120/240 motor will connect the two halves of the run winding in parallel or in series for 120 volt or 240 volt operation, respectively. If a motor is drawing 10 amps running on 120 volts, there is a drop of 120 volts and a current draw of 5 amps through each half of the winding. Each winding will see a power draw of 5 amps x 120 volts or 600 watts.

If the motor is converted to 240 volt operation, the winding halves are in series so the voltage is divided and each winding sees a voltage drop of 120 volts. The current is half what it would be for 120 volt operation or 10 amps /2 = 5 amps. The power draw for each winding is 5 amps x 120 volts or 600 watts. The same as for 120 volt operation.

The big difference is that the line is only supplying 5 amps at 240 volts rather than 10 amps at 120 volts. This lowers the line voltage drop which provides more voltage to the motor. Motors are particularly sensitive to drops in line voltage and tend to run less efficiently, producing less useful torque and more heat. Because less torque is produced, loading the motor causes even more current to be drawn, dropping the line voltage even more and making the situation even worse.

In addition, loading the motor drops the rpm which increases the chip load on the cutter requiring even more power unless the feed rate is reduced accordingly. All of these factors will come together to create the perfect storm, causing the rpm to drop to the point where the start winding kicks in, drawing even more power and eventually stalling the motor and, if continued, overheating the motor.
 
If starting capacitor open try this simple thing.

Place drill chuck in spindle.

Get chunk of rope and some masking tape

Make a flag on ed of rope with tape and grip fly in chuck.

Put mill in lower speed if step pulley.

Wind rope around chuck and give it a pull like a top.

Shift belt on pulleys until you get a good motor spin.

Give it a spin and turn on power while spining.

It it runs cap is bad

If no workie go possible other issues but this is simple and quick.

Many HVAC places have caps.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
I was making chips today on my 8520 and all of a sudden everything stopped and the motor would just hum. It won't even do that in reverse. Apparently the thermal protection didn't protect very well that motor casing was almost to hot to touch. Well, it's smoked, I'm sure of that. I called a guy about a rewind but he hasn't called me back yet. It's a 3/4 hp Baldor motor. A new shiny one is around $300 I don't know what a rewind will cost. So other than this bad news, I actually have a question. Motors are not my strong point. If I have to go the new motor route, is there any harm in upgrading the horsepower? Say a 2 or 3 horse motor? I'll keep the RPM's the same but I would think with a higher HP motor, it would labor less and stay cooler. Can that damage the machine at all? What are any pro's and cons?
If there is an overload device on that starter,it should be adjusted or possibly changed to protect the windings at the lower current draw. If there is a little dial on the starter it can be adjusted. If it has separate "heaters" they can be changed to protect the windings. There should be instructions for the starter.
 
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