VFD and 110 3 phase motor chatter - please help!

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GiantIsHere

Joined
Mar 22, 2016
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I recently purchased a good grinder from a reputable known grinder maker here in the USA. Ever since day one, there has been a terrible chatter. You can see it in the grind. You can see the belt wobbling back and forth. And you can just hear this super loud ticking noise that changes frequency as the speed changes.

The manufacturer has sent me a new VFD and a new motor and I still have the same problem. I've taken the entire setup to a few businesses in town just to make sure it's not my wiring in my shop. It's not. I've taken apart and reset the wiring. It's tight and true.

Anyone out there have any idea as to what it causing this?

He told me I could send the new VFD in to have it checked. That's another 2 weeks with no machine. This thing has been sitting in my shop for over 2 months now shipping stuff back and forth.

He agreed to a return since we can't figure it out, but I have to pay return shipping. $300. So far I'm super frustrated. I guess back to my 1x30s for now. So bummer. Any help would be appreciated.

Thanks.
 
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Sounds like a bearing problem. My bearings are going out and need to be replaced and it makes a ticking sound as well.
 
I've run the VFD and motor by themselves and its definitely something there. I'd i run the motor below 50% he motor tries to run off the work area
 
I know this sounds silly, but have you tried a different belt type on it? Or, run it with no belt to listen to the sound?
 
That sounds like a mechanical problem, not an electrical one. Is there a sheeve that goes on the motor shaft that allows you to drive your belts? Sounds like there is imbalance on whatever is attached to the shaft of the motor. It's an AC motor with a VFD output, so there really isn't a wrong way to hook it up, if it's hooked up wrong, it'll just run backwards, swap two phases and you're back in business... Your problem sounds mechanical in nature
 
evancamp13 said:
That sounds like a mechanical problem, not an electrical one.
Click to expand...

That's what I'm thinking as well. Maybe one of your wheels is out of square with the others. Maybe you've got a bad bearing as suggested. Maybe your belts are the problem. Maybe one of your wheels has a burr or ding somewhere. I'm betting it's not the VFD or motor.
 
It's really hard to diagnose without some pics and a video even... That would help immensely!
 
GiantIsHere said:
I've run the VFD and motor by themselves and its definitely something there. I'd i run the motor below 50% he motor tries to run off the work area
Click to expand...

Is this direct drive or a belt/pulley setup? Either way, start by eliminating as many variables as possible: Remove everything off of the motor shaft (drive wheel or pulley) and try running it again. Is it showing the same problems?

Also, what kind of VFD and motor is it?
 
So you said with the motor free and disconnected from the grinder it trys to walk off the table when at 50% speed or slower. If you spin the shaft by hand do you feel a bump? My motor when turned WAY down will jerk but that's running it at like 100 rpm. We need at least some pictures of the set up and a video would be better.
 
I missed that part about the motor shaking when it is not on the grinder.

If that is so, the shaft is likely bent, or another internal alignment issue in/on the motor is the problem. The VFD can make the motor pulse, but not shake.
 
He also mentioned that he was sent a brand new motor and VFD, but still having the same issues from both old and new of each.
Hard to believe both motors had a bent shaft or bad bearings. I might suspect an unbalanced drive wheel, or something in the drive train of a belt/pulley system, but brand new, that's also unlikely (but not impossible).
We definitely need some more info here.
 
GiantIsHere said:
I've run the VFD and motor by themselves and its definitely something there. I'd i run the motor below 50% he motor tries to run off the work area
Click to expand...

Normal

It happened to me and was discussed here before


Put a good wheel on the shaft.
The flywheel weight smooths out the movement.

and you have less of that jittering.
 
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