The Hum Of Death!

[planeflyer21]

Followed by death of the motor on my G4003.

Was finishing up a piece of aluminum, moved the lever to the forward position and got a hum after an initial jolt to the spindle. Shut it off, manually turned the spindile to see if the gears were jammed. They weren't.

Tried forward again and it worked, reverse worked. Was thinking "Now I should take the headstock apart and see what is grabbing." Put on the 4-jaw, faced a piece of SS stock, measured, moved to forward again and...

Hum of death again. Spindle was not moving, in either forward or reverse. Kept trying the direction lever on the apron, attempting to discern if the hum was coming from the motor or not.

And then the hum stopped. Enter explitive here.

Lights come on/stay on. The switch clicks when the lever is moved to either forward and reverse. Nothing from the motor.

I have yet to start testing. Where would you start?

This may be an opportunity to upgrade the motor but I will start another thread for that.

 

[jeff_g1137]

Hi
you do not say if it is a 1ph or 3ph 240v or 440v ???
take the top off the motor wiring box & smell is there a pong of burnt wire.
if it is humming one of the phases is not working. test the 3 coils to earth.
jeff

 

[John Hasler]

Followed by death of the motor on my G4003.

Was finishing up a piece of aluminum, moved the lever to the forward position and got a hum after an initial jolt to the spindle. Shut it off, manually turned the spindile to see if the gears were jammed. They weren't.

Tried forward again and it worked, reverse worked. Was thinking "Now I should take the headstock apart and see what is grabbing." Put on the 4-jaw, faced a piece of SS stock, measured, moved to forward again and...

Hum of death again. Spindle was not moving, in either forward or reverse. Kept trying the direction lever on the apron, attempting to discern if the hum was coming from the motor or not.

And then the hum stopped. Enter explitive here.

Lights come on/stay on. The switch clicks when the lever is moved to either forward and reverse. Nothing from the motor.

I have yet to start testing. Where would you start?

This may be an opportunity to upgrade the motor but I will start another thread for that.

If it's a single phase motor capacitor start motor the centirfugal switch may have been sticking. When you let it "hum" for too long it may have overheated and melted fusible link buried in the wndings. On higher quality motors these are self-resetting.

Take it to a motor shop.

 

[planeflyer21]

If it's a single phase motor capacitor start motor the centirfugal switch may have been sticking. When you let it "hum" for too long it may have overheated and melted fusible link buried in the wndings. On higher quality motors these are self-resetting.

Take it to a motor shop.

For rebuild?

 

[John Hasler]

For rebuild?

May not need a complete rebuild.

 

[rgray]

I have a Shop fox M1112 gunsmith lathe. I believe it is the same. Mine did something like this twice. Fist time was early in it's life had only had it 5 months or so. The electrical box on the motor was pinching one of the wires inside till the insulation broke through and it shorted to another terminal. Quick fix once found.
Second time one of the 1000 screws on the contactors lost connection intermittently. All the contactor screws were barely snug tightened them all up and has been running fine since 2013.

 

[Bob Korves]

Your 4003 should be single phase unless it has been modified. First make sure that you are getting full voltage and have good connections all the way to the motor. Disconnect the lathe from the power and check that all the connections in the electrical box are tight, clean, and not damaged or smoked. The centrifugal switch on those motors causes most problems. If you can start the motor by turning it by hand (CAREFULLY!) while it is humming, the centrifugal switch or the capacitor, or their wiring is probably your problem. Take the motor apart, no big deal, and look at how the centrifugal switch snaps in and out of contact and also the condition of the contacts where they rub on the slip ring. The switch must be mechanically reliable and the brush contacts must be clean, shiny, and making good contact all the way around the circle. They can be polished if needed, and they usually do need it. Check the wiring to the capacitor and the rest of the wiring as well for good, solid connections. If all that seems OK, take it to a motor shop and have them check it out. Could be a bad capacitor. It is not good news that the humming has stopped, if there is still power to the motor. If there is power to the motor, but no humming, take it to a motor shop.

 

[Tony Wells]

If the contactors incorporate overload protection, make sure they are reset as part of your testing.

 

[planeflyer21]

Thanks everyone.

As mentioned above, it isn't humming anymore. Isn't doing anything anymore. It will be Sunday before I can get a look at it.

My truck is in the shop, so we're 1-car-travelling and getting behind on other things. When it rains, it pours!

 

[mksj]

Not an unusual event for the grizzly single phase motors, and seems to be common with the lower grade Chinese motors. I would pull the motor capacitors and check them, they often go and nothing happens motor wise. That it is no longer humming might mean something else went. If you want me to check the motor capacitors, I have a capacitor tester at my house and you can bring them by. If it is not the capacitors, I am not sure I would waste the money on having it repaired at a motor shop, just get a decent metric replacement or go 3 phase and a VFD. World of difference.

Mark