VFD and 110 3 phase motor chatter - please help!

This might help you... inside the VFD at the top are a row of trim pot adjustment screws. These make adjustments to the way the VFD runs your motor. If you go to the Beaumont Metal specialties website where they sell the KMG grinder and look at their motors you will see a link to instructions for setup and near the end of these photos and instructions it gives the suggested Trim pot settings recommended by Beaumont. Use these settings and try your grinder again. If that does not improve your performance then try to wobble your idler wheel without a belt on it and see if the bearings are sound. Does this happen when you use a contact wheel? or just the platen? I still think the problem is in the VFD settings. Did you make sure the jumper was set for 110 power ? Also is your motor 1.5 hp or less or is it a 2 hp motor. A 2 hp motor shoud be run on 230 volt but a 1.5 or less will run on 110 volts but the VFD must be set for the proper voltage. Read the Beaumont instructions and check them off before any thing else. Larry
 
LARRYZ10 said:
This might help you... inside the VFD at the top are a row of trim pot adjustment screws. These make adjustments to the way the VFD runs your motor. If you go to the Beaumont Metal specialties website where they sell the KMG grinder and look at their motors you will see a link to instructions for setup and near the end of these photos and instructions
Click to expand...

Yes

The "reputable known grinder maker here in the USA" should have already set this up for you.


The jitter you get bare motor is expected.
Mine cleared up with a drive wheel.

It accelerates until it hits it's limit, then backs off then accelerates.




When you are profiling against the platen, I think you feel the belt seam bump
Bulk profiling is best done on a serrated rubber wheel.
 
OP, do you have a dial indicator to check the run out on the shaft? from the videos it seems like it's coming from the internals of the motor which seems that it would be a vfd setting issue as others have stated. Hope you get it worked out! My Wilmont TAG has been wonderful w/ no issues.

12345678910 said:
Yes

The "reputable known grinder maker here in the USA" should have already set this up for you.
.
Click to expand...

Chris at Wilmont Grinders (if I'm not mistaken that was a Wilmont "Little Buddy") tunes each VFD on his grinders before they go out - unless one was overlooked on accident but 2 in a row as the OP indicates would be very unlikely. An interesting fact as of a year ago, Chris sets up the VFD's on his grinders to utilize a build in motor brake so when you flip the switch to turn off the motor it stops the belt instantly which is very nice. Not everyone does this though.
 
I agree with Larry and Chuck. Double check your jumpers and trim pots and make sure everything is set up for your motor correctly.
 
Remove the platen from its bracket and run the grinder. I think maybe you have the platen
set too far forward and you're catching the belt splice on the top leading edge of the platen.
It's a quick easy check.
 
Well. I just talked to him and he's sure that it's set up right. I don't know want to do now. He'll take it back if I cover shipping. Do I send it back and get a KMG? Thoughts? Anyone?
 
GiantIsHere said:
Well. I just talked to him and he's sure that it's set up right. I don't know want to do now. He'll take it back if I cover shipping. Do I send it back and get a KMG? Thoughts? Anyone?
Click to expand...
I think you said it would be $300 bucks to ship it back from where you're at. In my opinion, that's a lot of money to waste, as the Wilmont is a good grinder. Knife making involves a lot of problem solving and if it was me, I'd figure it out.

Start by narrowing the problem down. If you've opened up the VFD and looked to make sure that all the trims and jumpers are set correctly, then you know for sure that is not the problem. I'm pretty sure Chris has it right, but it would only take a couple of minutes to double check. Next, I would take out a lot of factors by removing the belt and running the motor with just the drive wheel. Take a video with this set up and show us what it sounds like at all speeds, give us a bit of time to listen. In your first video you only gave us a couple of seconds to hear what was going on with just the motor running slow. By running just the motor with drive wheel you have eliminated any problems that might be from the belt or bearings or any other part of the basic machine. If it still does it without the belt, then you have it narrowed down to the VFD, motor or drive wheel. You could try finding another motor to hook up to the VFD, if still does it, then you know it's the VFD which shouldn't cost $300 to send back to KB elec which has great tech support.

Hang in there, it's very satisfying fixing something like this. Before it's over, you will sure know more about your grinder and will be better prepared to fix it the next time a noise pops up.
 
FWIW, I happened to have been in the process of wiring my first KBAC drive when this thread was started. Plugged it in last night, and at lowest speeds, it does "pulsate" or vibrate a bit. It's not terrible though. I do have a 5" solid aluminum drive wheel though, which may help.
 
The vfd has a "boost" function which only comes into play from 0-15 hz. Jumper J6 controls if it is fixed or adjustable. In unloaded condition that might be causing some speed control issue...
 
Have you tried something as simple as using a different belt? Did you try running it without the platen in place? Lastly, what is the rpm of your motor...is it a 1725 rpm or a 3450 rpm motor? We need more information to track this down. Have you checked the VFD installation instructions to make sure all the adjustments are correct and the voltage is set right? Did you set the horsepower jumper to match your motor horsepower? You need to check more things before sending this unit back. Larry
 
Just to add a little more to the discussion:

As I mentioned, I'm seeing a little bit of the same issues with my new set up, and sometimes if I hit just the right spot, it can get a bit worse. I did a little searching on some other forums, and it was recommended to another user (having similar issues) to change over to VT (variable torque) instead of the default CT (constant torque). I tried this, and wouldn't you no, ALL of the vibrating went away.

UNFORTUNATELY, this also removes all of the torque on your lower speeds, and if you have any tension on your belt, or just put your finger on the drive wheel, it stops the motor from turning. You can mitigate this SLIGHTLY with the boost feature by switching from fixed to adjustable and cranking the pot all the way up. Of course, when you do this, guess what? The vibration comes right back.

Just turning the pot left and right while the machine is running, however, you can see/feel/hear the vibrations changing along with it.

Ultimately I switched it back to the original settings, as the vibration wasn't terrible anyway, and I'd much rather have my low end torque back.
 
Well. I watched Chris' video on tuning the machine put on a 3m belt and it all started working perfectly. Like the stars aligned. I stayed out in the shop way to late because of that. Good problem to have.
 
GiantIsHere said:
Well. I watched Chris' video on tuning the machine put on a 3m belt and it all started working perfectly. Like the stars aligned. I stayed out in the shop way to late because of that. Good problem to have.
Click to expand...

got a link to the video?
 
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