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Resonance

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Resonance

Postby Phil » 25 Sep 2020, 10:30

Here is another one for Bob :D

While the big Hegner is out of action, I wheeled out the small Hegner to do some cutting.

While the motor is running with the blade under tension, the noise sounds like "resonance" (the closest description that I could find.)

Any idea what could cause it?
The machine runs smoothly.
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Re: Resonance

Postby Malc2098 » 25 Sep 2020, 10:37

Is that description the same sounds as a twin engined aircraft humming, or beating was we guitarists call it?

It occurs when two close sound sources are just a couple of herz different from each other.
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Re: Resonance

Postby Phil » 25 Sep 2020, 11:00

Malc, it sounds like a volume switch being turned louder then softer (closest description)
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Re: Resonance

Postby Malc2098 » 25 Sep 2020, 11:23

Phil wrote:Malc, it sounds like a volume switch being turned louder then softer (closest description)



Tremelo.
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Re: Resonance

Postby 9fingers » 25 Sep 2020, 14:17

Malc has got it in one!

you might be able to experiment by adding a little extra weight on one of the moving parts and seeing if that raises the beat frequency to a more acceptable point.

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Re: Resonance

Postby Phil » 26 Sep 2020, 12:00

Thanks Malc & Bob.

Maybe I will stick to the current beat 8-)


DrumBeat.gif
(125.37 KiB)
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Re: Resonance

Postby Phil » 07 Oct 2020, 15:07

Machine running with top arm connected and blade inserted


[youtube]Rd4CMi-0VlQ[/youtube]


Top arm disconnected

[youtube]xi9lAvhQXP8[/youtube]

So, the problem seems to be related to the top arm and driving mechanism.
Will have a look.
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Re: Resonance

Postby droogs » 07 Oct 2020, 18:28

check the pivot point at the back of the top arm, could be a crack
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Re: Resonance

Postby Phil » 08 Oct 2020, 07:50

droogs wrote:check the pivot point at the back of the top arm, could be a crack



Will do, thanks.

I will strip everything off and inspect, both arms and drive.
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