Grinder Motor Start Up Issue

J

Josh Conder

Joined
Apr 29, 2018
Messages
36
I just upgraded my motor to a 3 HP Blador running off a KBAC 29. Everything is wired as my motor in the past, but if you can see the video below it is having some issues. Any ideas what the issue may be?

 
Bearing? What rpm does the motor turn as it's running (can you check RPM with meter?) does rpm change with speed pot setting?
 
It sounds like its not coming up to speed/ full torque? Is that correct?
 
After rereading the manual. I noticed I had the J2 jumper in the B position when it should be in the A. This solved the high end speed and vibration, but I am still getting the same vibration when I go down to 50% on the drive. New video below.

 
Is the fan blade rubbing? With the VFD off, does the shaft turn smoothly? Do you hear the noise if you spin it by hand?

I might take the fan cover off and see if something is rubbing.
 
Motor turns extremely free and smooth when turned by hand. I did stumble onto a thread on a machinist page where the guy had the same setup and issues and KB told him to switch to variable torque setting as opposed to the factory default. He said KB didn’t offer an explanation as to why this fixed the issue so I’m not sure what it does, but it solved my problem lol.
 
Josh Conder said:
Motor turns extremely free and smooth when turned by hand. I did stumble onto a thread on a machinist page where the guy had the same setup and issues and KB told him to switch to variable torque setting as opposed to the factory default. He said KB didn’t offer an explanation as to why this fixed the issue so I’m not sure what it does, but it solved my problem lol.
Click to expand...

I guess I misunderstood. I thought the squeaking noise was something rubbing on the motor. As for the vibration, I do get that a little bit on the lower speeds on mine as well, if I set it to Constant Torque instead of Variable Torque.

It went away for me as well with variable torque, but the problem then became that at low speeds I could stall my grinder VERY easily, so I changed it back to constant torque.
 
That is concerning. I do run a lowers speeds for a lot of things. I wonder why it won’t run with constant torque. I can’t run it at lower speeds with that type of vibration for sure though.
 
Ok update, just because of how much this has confused me. Put the drive wheel back on, had so little torque it couldn’t even get the belt moving. So I switched it back to continuous torque and everything works perfectly. No vibration or anything. I’m at a loss for words lol
 
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