Drill Press Motor Repair Help

[Tutt]

I purchased two drill presses at an auction and neither of them have good motors. I would like to try to repair them, but i don't know jack diddley about motors. I have looked for a trouble shooting guide online, but i haven't found anything good. Perhaps y'all can help me out.

Motor 1:
120V 1PH
motor buzzes and will not start even if spun by hand. motor spins freely when off

Motor 2:
220v 3ph
starts and works, but pulls over 2x the current it should according to my VFD. It also gets very hot. Seems to have good torque and work fine other then it getting hot.

Any hope for these?

Josh

 

[genec]

the centrifugal switch is welded shut.

 

[Tutt]

Thanks for the reply! Are you referring to Motor 1? Is it likely that i can fix the switch or does it need to be replaced?

 

[John Hasler]

I purchased two drill presses at an auction and neither of them have good motors. I would like to try to repair them, but i don't know jack diddley about motors. I have looked for a trouble shooting guide online, but i haven't found anything good. Perhaps y'all can help me out.

Motor 1:
120V 1PH
motor buzzes and will not start even if spun by hand. motor spins freely when off

Without knowing what sort of motor it is, I'd guess a bad start capacitor or possibly a bad centrifugal switch. Try spinning it up with a pull rope. Capacitors are easily replaced and the switches are often just stuck.

Motor 2:
220v 3ph
starts and works, but pulls over 2x the current it should according to my VFD. It also gets very hot. Seems to have good torque and work fine other then it getting hot.

Internal short, most likely. Needs to be rewound.

Any hope for these?

Josh[/QUOTE]

- - - Updated - - -

the centrifugal switch is welded shut.

If that were the case the start winding would be energized all the time (unless the start capacitor was also blown).

 

[coolvilleshop]

Motor one, as the others said, capacitor bad , I really doubt that the motor would have start switch being on a drill press. Motor two, check that the motor is wired correctly for 240 volt, sounds like it is a dual voltage motor that the leads are wired for 480 volt.

 

[videotrack]

Motor one, as the others said, capacitor bad , I really doubt that the motor would have start switch being on a drill press. Motor two, check that the motor is wired correctly for 240 volt, sounds like it is a dual voltage motor that the leads are wired for 480 volt.

Re: Single Phase Motor:
If it's a single phase motor, then it's absolutely probable that it will have start winding and a run winding, and a centrifugal switch to open the start winding once the motor has started. It may also have a capacitor in the start winding circuit which is used to change phase angle between the two windings and thus provide a higher torque during startup.

There is a relationship between the placement of the start and run windings, and this is what causes the motor to start in the same direction every time.
With power disconnected, I would take the end cover off the motor which usually exposes the centrifugal switch. make sure the insulated sleeve can slide on the shaft, that the spring returns on the counterwights aren't stuck, and that the contacts are clean and open/close freely.

If it has a capacitor, you may be able to make a simple test with a multimeter set on ohms, connect to the capacitor and the displayed resistance value should gradually increase, revers the leads and it should show low resistance which will then gradually increase again. Make sure that your hands aren't touching the leads/probes as this will affect the readings.

testing for shorted tuns is much more difficult, and usually required specialized equipment.

The fact that is buzzes but will not start is a bit puzzling, usually if the start winding is O/C it will start if you give it a bit of direction (e.g. spinning by hand).

Hope this helps

 

[Tutt]

Thanks for all the help so far!

I took the end cap off motor 1 today and snapped a few pics.

i tried the pull cord trick with no luck.

the centrifugal switch seems to be working also. It slid free and the weights were free. The contacts looked pretty clean. There was a bit of discoloration from arcing, but they were smooth.

i also put an ohm meter on the cap. Testing it both ways the resistance settled in at about 4 ohms. It started at about 22 most of the time but seemed to vary every time I did it.

here some pics of it.

 

[videotrack]

Thanks for all the help so far!

I took the end cap off motor 1 today and snapped a few pics.

i tried the pull cord trick with no luck.

the centrifugal switch seems to be working also. It slid free and the weights were free. The contacts looked pretty clean. There was a bit of discoloration from arcing, but they were smooth.

i also put an ohm meter on the cap. Testing it both ways the resistance settled in at about 4 ohms. It started at about 22 most of the time but seemed to vary every time I did it.

here some pics of it.

There'sa 5.6K Ohm bleed down resistor across the cap, you would need to have that disconnected, and the leads into the motor disconnected when testing, so the only thing you are measuring is the two capacitor terminals. The 4 ohms measurement you see is likely to be the winding resistance, unless the cap is short circuited (and that's another possibility, except you would not expect to see 22 ohm reading in that case)

Is there a value on the side of the capaqcitor, like 4 mfd or 4 uFD (micro-Farad), if so, do you have access to a meter that measures capacitance?

 

[John Hasler]

There'sa 5.6K Ohm bleed down resistor across the cap, you would need to have that disconnected, and the leads into the motor disconnected when testing, so the only thing you are measuring is the two capacitor terminals. The 4 ohms measurement you see is likely to be the winding resistance, unless the cap is short circuited (and that's another possibility, except you would not expect to see 22 ohm reading in that case)

Is there a value on the side of the capaqcitor, like 4 mfd or 4 uFD (micro-Farad), if so, do you have access to a meter that measures capacitance?

Just stick a piece of paper between the contacts of the centrifugal switch. That will open the start circuit. You should then read an initially low value across the capacitor which should rise to 5.6K.

 

[dwdw47]

The single phase motor has a open start winding or the centrifugal switch contacts are dirty and making a connection. The run winding is shorted to its self. Chances are from the motor left on when the start switch or winding failed. Toss it! cheaper to buy a 1/2hp than rewind one.

Three phase motor good chance its wired for the wrong voltage, shorted winding or one parallel windings is backward. The most logical is the motor or not a candidate for VFD, Square wave is hard on many 3 phase motors.
Just a thought without much information this is the many leads to follow. Good luck!
dwdw47