Dynamic balancing with a scope and small speaker

Using a small loudspeaker as a transducer to pick up vibrations from a spinnint rotor and measuring those with an oscilloscope. This allows me to quantify the vibration for doing dynamic balancing.

This whole method to have something to try to balance the vibrations of then new shelix cutter head on my jointer.

[strkr]

I’m a vibration analyst by trade and your method is spot on! The only additional thing we do with the “test” weight information is build a vector diagram on a polar plot to determine where the optimal final weight should be located. Then there is some math to determine the weight amount but that’s just some simple cross multiplication. Doing this all with a speaker and o’scope is just downright genius.

[gannas]

This is a pretty clever method! Thanks for sharing with us.

[aswells]

Really interesting to see a speaker used that way. All you need is a sufficiently capable rotary encoder for position tracking and you've nearly caught up to industrial impeller balancing systems.

[Philip]

Mind blown. It would never occur to me that there was an issue, let alone following such a logical approach to fixing it.

[sbwhddv]

Wow Matthias! You never cease to amaze me! The way you combine intuitive understanding with real-world electronic know-how is clever and clear. When I was a kid and built slot-car motors, (circa 1964) I just chucked the armature into a drill, spun it, and lightly touched it with a magic marker. Then wherever the marks were thickest, I drilled a small hole in the armature; Reversed the armature, and did the same thing from the other side. That was as close to dynamic balancing as a cash-strapped kid could get, But it worked.! Of course I didn't have access to these electronic measuring devices then, so that method was a tedious iterative process. Even now, I would have never thought of using a speaker to generate a readable pulse into an oscilloscope. Brilliant idea!

[jacobframe]

I love the low cost approach to everything you share. It is so refreshing in a world of "Look at all this cool stuff I got for free to show you, please go buy it".

[gustavogiorno]

That impresses me the most in your videos is the didacts you have. Even when I know nothing about what you are experimenting with I'm always able to understand the concept.

You would be a perfect college professor, for sure!

[R.Daneel]

I confused dynamic with active. I thought you were going to feed back the vibration into the weighted voice coil to damp them that way (with destructive interference). Your way makes way more sense. Particularly for the heavy cutter. Looking forward to the conclusion!

[tonyyuan]

With two speakers configured orthogonally and two channels on an oscilloscope, Lissajous curve could be displayed. You could directly find the vibration vector. If you further know the phase of the motor, you could even calculate and display the exact angle at which you should add or remove weight.

[rahuls]

Wow, I'm blown away by the analysis and the use of the speaker is ingenious. Thank you for the video.

[DJRockinRob]

Man! That was a super cool video! I am astonished by your method, as always. I dream of being "your kind of smart" but the truth is, I'm a little lazy about trying to be. However! You explain the details so perfectly that I sit here and think to myself "That makes total sense. Of Course that's how that works!". I truly do understand and follow your explanations. I just, would never have gotten there myself. "That" is what perplexes me sometimes. That's the fun in it all... Right?! I have thoroughly enjoyed every one of your experiments over the years. The mice experiments were lots of fun! I appreciate your dedication to not only the true and sometimes brutally honest results but also to the storytelling arc. Thank you.

[Jack_C_]

You could possibly get similar results using a 'vibration meter' app on your phone (for those of us without an oscilloscope).
I dynamically balanced the drive pulley on my metal lathe by taping an old phone to the headstock and measuring the vibrations.

[Smarwell]

I never knew how balancing could be done before this. Fascinating video.

[tullgutten]

This is quality content.
I like it a lot.
Balancing fans and rotating things with a cheap diy friendly way and increasing their lifespan, lowering the noise and vibration is a really good thing.

The earlier video you had with balancing a fan really helped me right after i bought a box fan (brand new) it wash shaking violently and dancing over the floor, but after a few minutws balancing it it became very silent and no noticeable vibration

[BradenEliason]

If you have a small mirror and a laser pointer laying around, you could probably do this completely analog. Put a piece of paper on a wall far away to mark out the sweep of the laser. The added benefit is electrical noise would have no effect.

[davebullard]

This looks like a job for a piezo transducer! Also thanks for the demo. I am about to buy one of those blowers and this will help a lot if it's unbalanced.

[randomhuman]

Absolutely the best video i have seen in the past thousands

[LeesChannel]

I'm very excited to see the process done with your planer!

[raffly]

Have you thought about marking a zero position with reflective tape and use an optical pick up to mark the zero position on your oscilloscope? That would make finding the “location” of the imbalance easier than trial and error.

[wizrom]

I proposed a system like this for using a speaker and diaphragm weight to dynamically balance motors about 20 years back on the electronics forums.
The one thing you missed which would have been an improvment would be to place the whole assembly on an elastic suspension, which could have been as simple as a springy foam block. Your setup was damping the vibration into the table which reduced the measurement amplitude and accuracy.
Very cool project! 👍