Belt grinder noise - pulling my hair out!

Sando

Sando

Knife Maker
Joined
Jul 4, 2002
Messages
1,148
I'm going nuts.

My 20 year old KMG was running fine. But I put on the "refresh kit" just because it's getting old. Basically it replaces everything with bearings. But then it started making an awful tick/thunk sound. I put all the old parts back on one by one and no change! I was using an old treadmill motor that served me well, but I swapped it out ... no change!

"Screw it!" I thought. I'm done with pulleys and a belt. I'll spend the $$$ to upgrade to direct drive with a nice Lesson motor and be done with it.

Well, you guessed it. It still makes the noise!!!! I have swapped out every moving part and no change. It even makes the sound without a belt on.

Somebody help.

Here's link to a video so you can hear for yourself: https://www.dropbox.com/s/7rpqx77op057frx/IMG_7012.MOV?dl=0
 
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I had an issue with mine where the vfd was causing some awful vibrations and shaking my whole table until I got it adjusted properly. Happened right after I switched motors. Can you tell what area of the grinder it's coming from to try to narrow it down?
 
Thanks Josh. The sound started when I replaced the bearings on the drive shaft. Since then, I've replaced the VFD and motor and all the bearings. Unfortunately, I can't tell where the sound originates. And you can feel it the same everywhere (motor, grinder, base, etc.)

polish avenger polish avenger you know that's a good idea. I've done some checking the bench, but I'll go do a detailed check.

It's so locked into the speed, .... aarrggghhhhh!
 
Sando said:
Thanks Josh. The sound started when I replaced the bearings on the drive shaft. Since then, I've replaced the VFD and motor and all the bearings. Unfortunately, I can't tell where the sound originates. And you can feel it the same everywhere (motor, grinder, base, etc.)

polish avenger polish avenger you know that's a good idea. I've done some checking the bench, but I'll go do a detailed check.

It's so locked into the speed, .... aarrggghhhhh!
Click to expand...
So the sound must come from there :)
 
Ken H> said:
Have you checked the drive wheel to see if it's loose?
Click to expand...
Several times. I even swapped drive wheels.

We can rule out the bench. I've stripped it, sat on it, wiggled it no change in vibrations.
I've swapped out the tracking wheel too. No change.

One thing that does make it louder is if I push up on the tension handle (increasing the tension).
 
Ken H> said:
Have you checked the drive wheel to see if it's loose?
Click to expand...
I've had this happen when a set screw was loose on My drive wheel.
-but he said it happens even when the belt is off.....


if it's vibrating, add rubber under the bench feet to help dampen
 
Sando said:
Several times. I even swapped drive wheels.

We can rule out the bench. I've stripped it, sat on it, wiggled it no change in vibrations.
I've swapped out the tracking wheel too. No change.

One thing that does make it louder is if I push up on the tension handle (increasing the tension).
Click to expand...
Actual spring or gas shock tensioner?
Maybe the gas shock is gritty, going bad?
 
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Is there anything other than that grinder mounted to the bench?
Nevermind....you said you stripped it.
 
Crag the Brewer said:
Actual spring or gas shock tensioner?
Click to expand...
It's a good ol' fashion spring.

OK, I ran without a belt and the motor vibrates.

So, I removed the drive wheel completely and I can still feel the vibration. Some speeds it's almost gone. But at about 55% power it's very noticeable (I'm sure it's a resonant frequency thing).

So it seems to be present in this motor. When fully hooked up to a belt and all, it just aggravates it.
 
Sando said:
It's a good ol' fashion spring.

OK, I ran without a belt and the motor vibrates.

So, I removed the drive wheel completely and I can still feel the vibration. Some speeds it's almost gone. But at about 55% power it's very noticeable (I'm sure it's a resonant frequency thing).

So it seems to be present in this motor. When fully hooked up to a belt and all, it just aggravates it.
Click to expand...
You said new motor?


it's a drive thing, then. Not set up/compatible with your motor?

dip switch settings. Wired correctly? Drive settings?
 
REK Knives said:
I had an issue with mine where the vfd was causing some awful vibrations and shaking my whole table until I got it adjusted properly. Happened right after I switched motors. Can you tell what area of the grinder it's coming from to try to narrow it down?
Click to expand...
OK progress .... finally.

Thanks for the settings hints.

BTW I can't find the pole information or where to set it in the jumpers.

I did change the switching frequency from 8 kHz to 12kHz and there was a marked improvement!

1683675627258.png
 
Hoss mentioned it

Wooden broomstick as a mechanics stethoscope

Put one point on the machine the rounded end on the cartilage near your ear hole.

Move it around to every bearing, every point on the frame.

Once you find it, it will be drastically louder in that spot, it will be obvious.


I suspect when you changed bearings, one got pressed out of shape.
 
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