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View Full Version : Think I may have buned up my lathe motor? :(



DebosDave
02-28-2010, 04:56 PM
I had just finished two parting cuts, and they were pretty hard, but I thought I ran it pretty slow. When I finished, I did 2 light facing cuts on the same piece, and then turned the lathe off to examine. When I tried to turn it back on, now the motor just hums. I took the cover off, and it was plenty hot. I have a fan on it now, and when it cooled down a little, I tried again, but just the hum... any suggestions? Is it fried and need to be replaced?

Thanks for any help

Dave

Alistair Hosie
02-28-2010, 05:01 PM
It might be but some motors have a built in safety device when overheating the switch off till it cools down again or you may have tripped a switch in the fusebox have alook if it has a fusebox.Alistair

vpt
02-28-2010, 05:01 PM
Did you try to turn the motor over by hand or with a wrench?

DebosDave
02-28-2010, 05:04 PM
I can still turn the motor spindle by turning the flywheel? on the lathe itself. Where the belts attach to the lathe. The motor arbor feels to turn very easily. If it blew a breaker it wouldn't hum at all, would just be dead. I will let it cool further and hope that there is an internal thermal over-heat switch. Do these just reset when they cool down?

Thanks again for any help

vpt
02-28-2010, 05:07 PM
Maybe something is happening with the starting circuit? Maybe grime or something is holding that starter centrifugal weight clutch thing back? This is 110v right?

polepenhollow
02-28-2010, 05:17 PM
Clean the starter circuit inside the motor.
Clean the contacts and the rotor.
Clean switch contacts. Check validity of connections.
If no sucess, your motor is trashed.
K Lively

KiddZimaHater
02-28-2010, 05:31 PM
I posted the same topic about 3 weeks ago. I tried replacing the capacitors, but they fried. Then fiddled with the centrifuginal switch. Nothing.
I ended up upgrading to a new Baldor 3-Phase motor with a VFD.

DebosDave
02-28-2010, 05:33 PM
Maybe something is happening with the starting circuit? Maybe grime or something is holding that starter centrifugal weight clutch thing back? This is 110v right?

This is 220v

DebosDave
02-28-2010, 05:34 PM
Clean the starter circuit inside the motor.
Clean the contacts and the rotor.
Clean switch contacts. Check validity of connections.
If no sucess, your motor is trashed.
K Lively

Thanks I will go through these checks. I may also replace the starting capacitor just to see.

Thanks!

DebosDave
02-28-2010, 05:36 PM
I posted the same topic about 3 weeks ago. I tried replacing the capacitors, but they fried. Then fiddled with the centrifuginal switch. Nothing.
I ended up upgrading to a new Baldor 3-Phase motor with a VFD.

This doesn't give me much hope LOL. I actually took a 3-phase off this lathe and replaced it with the current single phase. I still have the motor so I could go that route... will see what the other checks give me first.

Thanks

MTNGUN
02-28-2010, 07:09 PM
I actually took a 3-phase off this lathe and replaced it with the current single phase. I still have the motor so I could go that route...
? ? ? ?

3ph & VFD, don't look back.

RobbieKnobbie
02-28-2010, 07:52 PM
Make sure you're getting both legs of your 220. You may have lost it in the motor, at a relay or at a fuse - though both leg fuses should be bonded together so if you trip one you loose both.

If you give the motor a twist while humming, will it come up to speed? Then it's probably the starting circuit. Take the bell housing off and take a look at the centrifugal switch, the contacts etc. Then check the start windings for an open circuit (check the run windings while you're at it). If that's the case, bag the motor and start shopping for a frequency drive

Black_Moons
02-28-2010, 08:01 PM
Definately go back to 3 phase and buy a VFD, you'll love it on a lathe. fast stoping, quick reverse, speed adjustment while facing/cutoff, etc

DebosDave
02-28-2010, 08:26 PM
Can anyone point me to an affordable VFD that will also convert from single phase to 3-phase? Needs to handle a 3HP motor, so my understanding is I need a VFD rated for 5HP or better, and hard start? When I try to find these, it appears to only be 3-phase to 3-phase or prohibitively expensive

Dave

lakeside53
02-28-2010, 08:31 PM
You just need a single phase VFD rated at 3hp. The derating you likely read about applies to a 3 phase VFD runniing from single phase. I like the Hitachi SJ200 series (less than $300), but there are others cheaper.

IMO... there a 99% chance you just oiverheated your start cap - and it failed. I've seen tis many times. Replace the start cap and continue making chips.

DebosDave
02-28-2010, 08:33 PM
I am going to try the cap first, the motor did get pretty hot (is that normal?)

Thanks again

J Tiers
02-28-2010, 09:00 PM
I am going to try the cap first, the motor did get pretty hot (is that normal?)

Thanks again


There is hot, and there is hot... Motors can get to above boiling water temp and be within limits. No telling, unless it began to stink and emit smoke.

DebosDave
02-28-2010, 09:07 PM
It didn't get to the point that I couldn't touch it, and no smoke. I didn't even know it was hot until I took the cover off because it wouldn't start. I am going to test the starter cap tomorrow, and will go from there.

Thanks for all the help guys, it is much appreciated

Dave

Richard-TX
02-28-2010, 09:08 PM
If you have a 3hp 3ph motor then you have some choices.

If it were my lathe, the single phase motor would have been yanked and sold off long ago. When I upgraded to 3 phase all of that 1ph chatter and 1ph finish issues disappeared.

Teco makes a good VFD and it has a 2 year warranty and they are already rated for 1ph input.

Here is their basic VFD in the 3 hp size.
http://www.factorymation.com/s.nl/it.A/id.198/.f

Cost is $185.


Here is a little fancier Teco with a front panel pot and other features.

http://dealerselectric.com/item.asp?PID=370&cID=28&scID=165

Cost is $215.00 Without knowing your particulars, I would say go with the latter.

You will likely be much happier with the 3 ph motor and a VFD. It is what is being put on some of the better imported lathes like the one below.

http://cdn0.grizzly.com/pics/jpeg288/g/g0670.jpg.

Black_Moons
02-28-2010, 09:14 PM
Iv bought other things from this website and they seem good. so check them out
http://www.tools4cheap.net/products.php?cat=46
I kinda recommend the better NV series as they well, are better and allow use of an external braking resistor for fast stops (threading to a shoulder for example)
They do not need to be 'derated' because they are all designed for single phase input anyway.

the cheaper teco's either require a braking module or spec only 20% braking torque, the NV iirc is 100%+ braking torque.

KiddZimaHater
02-28-2010, 09:29 PM
When I did my upgrade, I purchased an "ABB Brand" V.F.D.
Here's a link to the 3HP variety.
220 Single Phase input, 220 3 Phase output, rated for 3 Horse motors.
http://abb-vfd.com/_product_18847/ACS150-01U-09A8-2_240_Volt_IP20_Enclosure

Richard-TX
02-28-2010, 09:29 PM
The Teco braking is the same design scheme across their product line. The FM50, EV, 7300, JNEV, all use the same braking resistors.

They all use an inexpensive resistor for maximum braking.

All of the Teco 1ph rated VFD do not need to be derated.


Tools4cheap is more expensive than Dealers.

For example the 3 hp Teco Ev from tools4 is $241.00
The same drive from dealers is $215.00

Here is where you can get braking resistors.

http://www.factorymation.com/s.nl/sc.2/category.6056/.f

$28 for a 3hp 230 volt resistor.