[Newbie] White Smoke From New To Me Mill Motor

[minions]

This past weekend I bought an old Bridgeport mill off of Craigslist. The seller was selling all his machinery. He claimed to have not used the mill in over ten years and looking at the ways it looked as if it had not been used in at least a few years.

The mill actually cleaned up better than expected and the motor belt seemed to move with very little resistance.

I wired up a 230v plug to the phase-o-matic static converter that was included with the mill then Boom! my dream came crashing down. White smoke started to come out of the motor while running.

I then changed the stepped pulley from 2700 rpm to 1700 rpm speed ( measured with a tachometer) and same result- white smoke after about 20 seconds of run time.

When it was at speed the motor and spindle actually seemed quieter than what I expected. I did touch the motor head after 20 seconds running it seemed very warm- borderline hot.

My questions are, can this be normal for a motor that has not been run in years? if not normal, any idea how I should proceed? remove motor or j- head and inspect?

Any help is appreciated.
Daniel

 

[dave_r_1]

I don't know about the mill, but you totally aren't supposed to transport children like that. At least throw a tie-down strap around them.

 

[GarageGuy]

This is just speculation because I'm new to Bridgeport mills myself having just bought my first, so this is just a theory. Doesn't a static phase converter supply 2 of the 3 phases to the motor, and reduce the rated horsepower by 1/3rd? Not positive, but I thought I remembered reading that. If so, a machine that hasn't been run in a long time may be stiff, and with a reduced capacity motor it may just be overloaded. If it hasn't been run in a long time, the grease in the bearings will get hard and the bearings tend to "cog", the belts may have taken a fixed shape that needs to be overcome, etc. Just a thought, and hopefully someone with more experience will be able to offer more substantive advice.

GG

 

[Martin W]

Hi Dan,
Very nice looking Bridgeport.
I wouldn't run it , until I put a volt meter on it. You need to make sure you have the correct voltage. Smoke is not normal from any motor. I have had all kinds of debris come out of a motor that sat for a long period of time. Dust, dirt and such.
Are you sure its a 230 volt motor?
I'm sure others with more experience will be here to help you out soon.
Congrats on the new mill
Martin

 

[John Hasler]

The motor should not smoke and should not get hot running no load. The motor is almost certainly 240 (could be 480 but that's unlikely). Take the motor off and inspect it. The data plate will tell you the voltage.

 

[minions]

Okay, I just checked- there is not 3 phase power coming out of the phase converter. Now I'm not sure if the motor damaged the phase converter or if it's just the old phase converter that no longer works. Thinking of just buying a single phase 220v motor rather than buying a new phase converter- does this make sense?

 

[Ulma Doctor]

the phase converter will not produce 3 phases of power continuously.
the Phase o Matic uses a potential relay.
the potential relay dumps a start capacitor's charge into one phase of the motor (the missing phase of the 3 phase motor) until the motor runs up to speed and the voltage increases sufficiently to open the potential relay and takes the start cap out of circuit again.

the insulation may have broken down on the motors winding and may be causing internal shorting
another possible problem may be with a failed/failing potential relay inside the phase o matic.
take care when opening the unit for inspection- a capacitor can be very dangerous.
discharge the capacitor before touching any circuitry

here's a short video i made a couple years ago that explains how to discharge a capacitor

 

[JimDawson]

Static phase converters don't output 3 phase. It is possible that the run capacitor has failed. I would keep the 3 phase motor, and install a VFD. You might want to take the motor to a motor shop to get it checked out. Sounds like it might have a bad winding.

 

[John Hasler]

Okay, I just checked- there is not 3 phase power coming out of the phase converter. Now I'm not sure if the motor damaged the phase converter or if it's just the old phase converter that no longer works. Thinking of just buying a single phase 220v motor rather than buying a new phase converter- does this make sense?

How did you check? A "static converter" does not generate three-phase power. What it actually does is convert the motor it is connected to into a capacitor-run single-phase motor. There's nothing in there but some capacitors and a relay. It's possible that the start relay in the converter is stuck, though. A failed start cap would not cause the motor to run smoothly but overheat. Regardless, a motor that has had smoke come out of it needs to be inspected.

 

[chips&more]

In my experience, I have had two SPC’s fail on me. Both due to the resistor in them. The caps and relay were good. It’s an easy one to trouble shoot and fix. The resistor will look fried. I changed them to a higher watt rating and all has be good. But a VFD is a much better 3ph option…Dave.