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Rivett 1020S - Video and electrical hum question

TravisR100

Cast Iron
Joined
Aug 7, 2006
Location
Houston, TX
I posted a short video showing the ways on the machine, an overview, and then the varidrive. I have some electrical noise coming from the motor both on startup and while running. Curious what that might be.

YouTube



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I say in the video when looking at the front ways that the wear seems like it’s probably less than .001”. Haven’t measured it yet but I can’t catch a finger nail on it. Just barely feel it when running a fingernail over it.


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I can’t even imagine how that belt comes off.

Going to check the electrical now. It’s being powered by a brand new 10 hp AMP rotary phase converter from American Rotary. Checked the output
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on the phase converter yesterday. All appears normal and wild leg isn’t powering control circuits.

Just checked the fuses and getting continuity through them. About to try to figure out which wires in the cabinet run out to the drive motor and check voltage on them.


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BFD?

I did check the voltages on the bus bar in the electrical cabinet going out to the drive motor. Between legs I’m seeing 233, 238, and 232. To ground I’m seeing 200, 119, and 120.


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Among the "fast and cheap" tests could be to place another 3-P device on the same RPC, running unloaded - and see if the 1020's motor is less growly if operated with the other load effectively acting as a supplementary idler.

Like that idea. May have to see if I can try using the motor on the band saw. Not sure yet if it runs.




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I’m not sure how to check the points but I’m sure I can do some googling. Could that even be the problem if I’m getting the proper voltages measured after the contactor? Amps also seem to be equal across each leg coming from the phase converter with the machine running.


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Thermite, tried your idea. I have a Doall V26 band saw sitting here as well. I think it’s a 1.5 hp motor. Doesn’t say but the amps rating is 6.2/3.1. I started that up first then started up the lathe. No difference.

Just as an aside, I had listed the band saw for sale but may keep it now that I’ve seen it run. Crazy how slow it will turn.


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I’m not sure how to check the points but I’m sure I can do some googling. Could that even be the problem if I’m getting the proper voltages measured after the contactor? Amps also seem to be equal across each leg coming from the phase converter with the machine running.


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Test the contactor from the inlet to the output side with a multimeter. With the power off of course, push the contact together and check the resistance between in and out on all the legs. The voltage going to the motor is what you want to measure.
 
IF.. the mag-starter's "contact points" are worn and/or.. especially if the actuating coil is on the generated - read "variable under load" leg .. it could be vibrating or "bouncing" in and out on one or more legs.

Now . a dropped-phase on a 3-P motor balks at cold start - but they keep on running if motating much at all if/as/when one phase (or more than one) drop-out whilst rolling- especially if it is only an intermittent drop-out, soon restored.

"Good luck" would be to find that the coil IS on the generated leg and just swap that - at the connection to the machine usually easier than inside the mag starter, FWIW.

That last part is easy enough to JF try it and see if it makes the growl go away - no further detective work required.

I did verify yesterday that the control circuit is not being powered off the wild leg. You said a 3P motor balks at a cold start. So you don’t think the motor has a dropped leg then if it’s starting, which it is?


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Test the contactor from the inlet to the output side with a multimeter. With the power off of course, push the contact together and check the resistance between in and out on all the legs. The voltage going to the motor is what you want to measure.

The voltages I posted earlier in this thread were the voltages measured that are going to the motor. I’ll go check the resistance on the contactor.


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So that I’m checking the right thing...

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I believe the contactor on the far right is the starting contactor and the two ganged together on the left is the reversing contactor. Is that correct?

EDIT: I figured out the contact on the left is the forward contactor, to the right of that is the reverse contactor, and the far right is the coolant motor contactor.


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I checked the contactors from the input to the output side. I just went ahead and checked every contactor in the panel. All measure less than 1 ohm. There were a couple however that seemed to jump around. Not sure if it was just my probe connection but doing multiple measurements and actuations of the contacts all would read less than 1 ohm.


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I don’t have a way to put much of a load on it other than just turning the spindle with the chuck on it at the moment. The sound is almost inaudible once it’s running. It’s only starting that I hear the growl. It sounds the same starting in forward or reverse.


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Don’t know if this means anything, but measuring the current on each leg going into the machine and out to the motor....

For both into the machine and out to the motor I’m seeing about 6, 9, and 9. At startup on one of the legs I’m seeing a peak of about 49 amps.


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Thermite I believe it was you that advised me in another thread to rewire the transformer for 220/110 as opposed to the 440/220 that it was wired for even though it’s being fed 220. I did that during my testing here just a little bit ago. It seems that after doing so the lathe takes a little longer to start and the electrical “grunt” noise lasts a little longer. I’ll also note that it tripped the 10 amp breaker on the phase converter on the first start after making this change so I moved the plug to a receptacle with a 20 amp breaker which is what it was supposed to be plugged into in the first place.


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RPC: It's definitely big enough to run your lathe and the AMP comes with the proper 'stuff' for hard starting

Reeves Drive Belt: It's loose, but it seems to work. The reeves in the Rivetts are fairly tight

The Hum: If someone missed the control circuit transformer when converting the machine from 440 to 220, it is very likely that they missed the wiring of the reeves drive control motor that gets its power from the windings of the main motor. I do remember that the wiring to that motor changes with the voltage change. I have no idea if that would cause your hum, but it seems plausible to me. You could have a variable/non-complete phase loss that is most prominent on start up. One of the windings is seeing a voltage mismatch on starting? Of course, this assumes that the quick-and-dirty tests that Thermite suggest are negative. I would check your mag starter too.

Another thing to check while you're cleaning up loose ends is the motor brake. The motor brake uses a coil to lift the brake and that coil needs to be changed to the appropriate size when converting from 440 to 220. If they missed the control circuit transformer, then they definitely missed the coil in the brake.
 
Good catch!

I didn't know it had such a critter, but that clatter CAN BE characteristic to either a Warner or Dings brake seeing a momentary drop as to hold-off. Those I DO have. Most of us have heard it on automotive AC compressor clutches, too. Same tribe, conceptually - different Voltage.

I didn’t think about that either. I looked at the brake motor data plate and it does say 222/440. But maybe they missed wiring that up for 220 and that’s the problem. My understanding is that without power the brake is engaged and power is what causes it to disengage. So maybe what I’m hearing is the brake being slow to disengage? It is a Dings brake.


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Here’s a pic of the motor data plate. Sorry it’s hard to read. Difficult to get a good picture. It says...

TYPE V0-J
Volts 220/440
Min RPM 500
Max RPM 3470
PH 3
Code H
Design B
HP 5
LO volt amps 17.5
HIGH volt amps 8.8
Rating 55 C
Serial 2822956



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