Grizzly G0490 8" Jointer Motor Noise on Shutdown

[Pat Moy]

I took delivery of a new Grizzly G0490 Jointer last week. Setup was relatively easy. Jointer runs fine and cuts smoothly. However, after around an hour of total usage (with multiple turning on and off), the motor starting making a surging sound when turned off (the motor spins down when I hit the off button, then I hear a clicking sound, which I think is normal, then the motor seems to spin up briefly before shutting off). The drive belt also vibrates when this surge happens. Motor still makes this noise after I disconnected the drive belt, so problem is unrelated to drive belt or cutter head.

I called Grizzly tech support about this. The tech rep said noise is caused by motor braking. He says since motor is still spinning shortly after I hit the off button, the energy has to go somewhere. This energy dissipates by trying to spin the motor in reverse direction, which supposedly causes the noise. He also said this shutdown noise is normal for some motors, and that nothing can be done. He didn't have an answer when I asked why this noise didn't happen from the start. He also couldn't explain why it happens on some motors and not others. To me, this is just poor quality control.

I have other woodworking machines with 3 or 5HP single-phase induction motors. Since none of these machines make this noise, I'm not sure I buy the Grizzly rep's explanation. In any case, the tech rep says nothing can be done.

Has anyone come across this problem with a Grizzly machine and found a solution?

[Chuck Wintle]

That explanation from the Grizzly rep sounds bogus to me. If the motor did not originally make this noise then it should not be doing it now. It could be as simple as a loose drive belt that slops around a bit as the motor is slowing down. Maybe try adjusting the drive belt.

[Pat Moy]

I don't think the problem is related to the drive belt. Motor still makes this surging noise on shutdown with the drive belt is completely disconnected from the motor pulley.

[Sean Kinn]

Obviously, describing clicks, vibrations and noises can be very subjective and subject to a lot of individual interpretation. I will say that my Grizzly G0555x bandsaw has what seems to be the same characteristics on shut down. I'll hear two clicks or so, motor is spooling down, then it'll get the shakes for a a second or two as it slows through a certain rpm range. My garage floor is very uneven, and gives me fits with trying to get the 4 adjustable feet on the bs level. I figured the vibration was the combination of the drive belt having sonmewhat of a "set" to it, and the issue with me nt being able to get the feet aligned 100% perfectly to avoid very minor rocking. I was planning to remove the belt and do a little vibration trouble shooting soon....I'll report back.


P.S. For what it's worth, my Delta 17-950 DP makes a few similar clicks when shut off and spooling down.

Edit: I had typed the above response and in the meantime you responded about it not being the drive belt. I'm fairly positive my Grizzly motor does not surge, but I'll go have a listen again tonight.

[Rod Sheridan]

The clicking sound on deceleration is normal, it's the centrifugal starting switch.

Rotating machinery will be designed for a certain speed, and the machines rotating parts will be balanced, and have a resonant frequency that's outside its normal speed range.

As the motor decelerates, it may pass through its resonant speed, which can make odd sounds, which may sound as if it's speeding up.

Regards, Rod.

[Pat Moy]

I am not 100% sure that the motor is in fact speeding up before shutting off. However, I do know it makes a loud sound before shutting off, which as I mentioned earlier, didn't happen initially. Before this started to happen, the motor just shuts down quietly when I pressed the stop button.

I guess the bottom line is that given this didn't happen initially, is there anyway to get the motor to shut down quietly as before?

[Chuck Wintle]

Your best bet is to talk to someone who really knows electric motors to get an opinion as to why it is now suddenly making a noise.