Loud Motor Hum - Solved!

[mark1]

I've only had my T7 for a week or two, and at first it ran very quiet, but this past weekend I was working late into the night in my poorly lit garage and it was making a loud hum. I thought that was weird since it is so new. I gave up soon after and went to bed. The next morning I came back out and went to work again - this time, since it was day, I removed the magnet base lamp I had stuck to the T7 body the night before. The machine was once again whisper quiet! Magnet lamp on the T7 - loud. Magnet lamp taken off the T7 - quiet!

Looks like the magnet at the base of the lamp was powerful enough to interfere with the magnetic field inside the motor. Lesson learned.

Now, I just have to find (or make) a lamp with a post base that fits into one of the fitting holes on my T7. I'll keep you updated.

[Elden]

   Welcome to the forum, Mark. That is very interesting information. Thanks for sharing it. It would be interesting to know if any others run into the same type of situation.

[jeffs55]

That does not sound right to me, I would look and see if the lamp was solidly built and not vibrating in some way.

[mark1]

I agree Jeff - it is weird. Do you have a large magnet you can put on yours to try to reproduce the issue? If you do, put it on the  nameplate sticker on the front.

[Jan]

Looks like the magnet at the base of the lamp was powerful enough to interfere with the magnetic field inside the motor.

Interesting thought, Mark! 

The electromagnetic field generated by the motor is quite effectively shielded by the Tormek steel housing. Steel, as a ferromagnetic material, concentrates the magnetic field within itself. Only small fraction of the magnetic field penetrates beyond the steel shield. It applies to the magnetic field of the motor on one side and also to the magnetic field of the lamp holder on the other side of the steel housing.

Like Jeff, I see the source of the hum in the mechanical vibrations generated by the TORMEK grinder.

Such vibrations are very common and can be caused by small imbalances in the rotating parts or uneven friction of the reduction gear. This small periodic vibrations can cause hum, when its frequency is near to the resonant frequency of the lamp or other resonator. You can change the resonance frequency of the lamp by attaching a small weight to it.

Jan

[jeffs55]

I used a 2 x 2 x 1/2 inch rare earth magnet on two different machines. I placed the magnet as you said, on the label and on the motor housing itself. There was no perceptible difference in sound or vibration.

[mark1]

Thanks for trying to reproduce my experiment Jeff. After reading your reply I re-checked my theory on my own machine and no hum. Now I'm really confused why it ever hummed in the first place. It could have been the lamp, but it was definitely a noise coming from the motor.

I'm really liking this forum - not many forums have this kind of involvement from the members.

Myth Busted!

[OnealWoodworking]

What you experienced was vibration and they can do that at times depending on the surface used and what is actually on the machine at the time.

When I want mine dead quiet - I do NOT stick the angle jig to the machine. That alone can cause noise that would otherwise not be there. 

[Ken S]

Interesting topic. Good observation about sticking the anglemaster, OW. I have not experienced the hum, but will keep the suggestions in mind should it occur.

One of the appealing things about working with the Tormek is its quietness. This quietness allows us to concentrate on the sound feedback of the grinding itself. Our senses can teach us a lot about working with the Tormek.

I believe Yogi Bera quipped, "We can see a lot by looking."

Ken

[Rob]

Oh....the wisdom :-)

[Ken S]

You guys may have had Shakespeare, but we had Yogi!

Ken

[Rob]

Lets hope we keep the "boo boo's" to a minimum :-)

[OnealWoodworking]

Interesting topic. Good observation about sticking the anglemaster, OW. I have not experienced the hum, but will keep the suggestions in mind should it occur.

One of the appealing things about working with the Tormek is its quietness. This quietness allows us to concentrate on the sound feedback of the grinding itself. Our senses can teach us a lot about working with the Tormek.

I believe Yogi Bera quipped, "We can see a lot by looking."

Ken

If using your Tormek on a proper surface - You likely never will experience any hum or serious vibration.

When I use mine on a 'poor' work surface is the only time that I have issues with vibration. I blame myself for that and not the machine.

Completely agree with you about the quietness of the Tormek.

[Ken S]

Interesting observation on the importance of having a proper surface. This reminds me of Chris Schwarz' writing about planing: The fore (jack) plane for rough shaping; Then the jointer plane for flattening; And, finally, the smoothing plane for creating a fine surface. Shaping, sharpening, honing and polishing. Do not pass go until the prior operation is complete.

Good post, OW.

Ken

[Elden]

none,
   That indeed is an interesting point which you bring up. I will try to file that in Memory.