The other thing to notice is the omega squared term. Things get bad fast at high speeds. You equation would imply that doubling the speed quadruples the magnitude of the vibration. Or going from 100 to 1000 rpm would increase the force 100x!
Thanks! Do you have any specific topics in mind? I don't really have further videos on balancing planned at the moment. Creating a balancing machine seems like quite a lot of work, and I'm not sure how many people care that deeply.
Dynamic imbalance = static imbalance + couple imbalance, so if you have a shaft that vibrates when it's rotating, one part of the vibration is caused by static imbalance, one part is caused by dynamic imbalance, and the total imbalance is dynamic imbalance. I'm not sure if those terms are universal. My analytical mechanics textbook makes no mention of the term "couple imbalance".
@@antalz Thank you. Reading a book written by Ricky Smith and Keith Mobley and it states..."There are four types of imbalance: 1. Static 2. Dynamic 3. Couple and 4. Dynamic imbalance combinations of static and couple. I appreciate your answer because the differences where not at all clear to me.
@@pkilo2811 Ow that's an engineering book. I find engineers like to define lots of catagories and situations. I was using a physics textbook, they like to define as few things as possible, it's more elegant like that or something. So my textbook only has static and dynamic.
I think you should ask a mechanic shop about that, that's very difficult to solve without a tire balancing machine. I guess you should add zink weights to the inboard and outboard part of the rim, to create a dynamic imbalance to offset the existing dynaminc imbalance, but how much weight to place where is nearly impossible to figure out without a balancer.
Nice demonstrations pieces, I haven't tried them but your video makes it clear enough that I can imagine holding them in my hands and feeling the results. Well done. In the future if you think one of videos enhances a comment that you are making about something that I've posted, include the URL so that others may more easily find it, always interested in other's opinions
Nice explanation. Now to my problem: my washing machine goes out of balance on the low speed spin (at the end of the wash and rinse cycles), but not on the high speed spin (occurs twice on the spin cycle). I observe that as the machine spins up the high speed spin (spin cycle), there is an intermediate speed where the machine starts to go out of balance, but the rate of increase in angular velocity fairly rapidly damps that out. On the low speed spin (wash and rinse cycles), the angular velocity seems to terminate right at the point where the out-of-balance condition is at a maximum. It seems to me that, under the imbalance condition, the machine moves from side-to-side rather than at random, and I suspect that this is because the base is narrower in the side-to-side direction than it is in the front-to-back direction. Thus, I believe that the oscillation of the spinning unbalanced wash basket hits a vibrational frequency of the washing machine base causing the machine to make unpleasant noises and to walk around. The machine is designed with a "balance" ring at the top of the clothes basket that is filled with fluid. I presume that this fluid-filled ring is supposed to dynamically counter any oscillations that result from an imbalanced load in the basket. Inspection of the basket shows that there is fluid in the balance ring and there does not appear to be any damage to the ring that would cause a leak in the balance ring. I am having a hard time visualizing how a relatively small fluid-filled ring at the top of the wash basket can adequately stabilize an unbalanced load of wet clothing in the bottom of the basket. Alas, for my model, the balance ring cannot be replaced and the cost of a new basket is nearly the same as the price of a new washer. I should point out that the wash basket, the outer container and the motor and gearing are supported on suspension rods with springs to damp out vibrations. I am thinking that, in addition to springs, the suspension rods should include dashpots to overdamp the motions. Any thoughts about this practical application of the points made in your video? BTW, your video was the best I have seen about the subject of instability of rotating systems! Thanks.
Looks like dynamic is just 2 plane balance, and that if the wheel rotated on a point instead of an axis you could determine dynamic imbalance using static methods?
Well that's a weird way to think about it honestly. Rotation is usually regarded as being around an axis. Perpendicular to that axis is a plane. Maybe by "rotated on a point", you mean having the object spinning in free space. In that case the object will always rotate around its center of mass. Another way of looking at dynamic imbalance is that the axis of rotation is not one of the principal axes of the object. I'm not sure if you can measure dynamic imbalance using static methods, I believe not, but honestly this piece of classical mechanics has been ages ago for me.
Actually you are correct, even about a point you couldn't measure dynamic imbalance. For some reason I imagined the bolts sticking out in different axial directions creating a couple in a static scenario, but they only do this in a dynamic scenario where the forces are radially outwards. In a static scenario in a gravitational field they're both 'down' and cancel each others turning effect.
nice demonstration. I didn’t know that was called dynamic balance I thought it’s just a way to balance the weel better, but it makes sense since it only occurs when you rotate it. I have a flywheel and it has a counter weight to balance the crankshaft and that means it can’t be balanced dynamically but that’s maybe one reason why the redline is 5500rpm .
That could be, though the flywheel itself should be statically and dynamically balanced. But balancing the crankshaft is very hard. You can look into primary and secondary imbalance, though I'm not very familiar with it myself.
Not sure about that honestly, I think people just ignore it. The keyway is close to the axis of rotation, so it generally doesn't create too much imbalance. I don't think people do it for gears either. For when it is done, I don't know exactly how.
Great video that really explains it. If one has dynamic imbalance how does one know the weight and distance from the center one needs to place it in order to counteract the dynamic imbalance?
That's actually quite tricky. What you can do is put the shaft in a pair of bearing, and then have the bearing housings supported by load cells. In this way you can measure how much force is exerted on the bearings, and by checking whether the force is in the same or opposite direction you can find whether you have static or dynamic imbalance. You can then run the math backwards to figure out where to place weights, but I haven't studied that math. You will have multiple solutions, you can use lighter weights if you can place them further out.
@@antalz One more question if you don't mind. I am creating a wheel balancer as I need to balance many thousands of wheels. The wheel is 2" wide, 7" in diameter. If I have static imbalance that means I will have to place a weight on each side of the wheel at some distance from the center of rotation, correct? If I also have dynamic imbalance I will have to also place a weight on just one side of the wheel also distance from the center correct?
@@Yoyo-ug7wt Kinda, but you got it backwards. Static imbalance can be fixed with a single weight, dynamic imbalance needs to be fixed with 2 weights. If you try to fix static imbalance with just 1 weight, you und up creating static imbalance which needs a second weight to be fixed.
@@antalz But I am not sticking a weight right through the wheel to the other side like in your video. I can only stick it on one side, the other or both. If the wheel is 2" wide and has static imbalance and my weights do not extend right through the wheel to the other side then I will be creating dynamic imbalance by placing the weight only on one side won't I? My wheels are solid plastic.
Impressive explanation! I love how you created the apparatus in a simple way and yet, very effective to demonstrate the phenomena. Impressive!
The other thing to notice is the omega squared term. Things get bad fast at high speeds. You equation would imply that doubling the speed quadruples the magnitude of the vibration. Or going from 100 to 1000 rpm would increase the force 100x!
Excellent .... these demo pieces clears the concept effectively. thank you.make more video on balancing.
Thanks! Do you have any specific topics in mind? I don't really have further videos on balancing planned at the moment. Creating a balancing machine seems like quite a lot of work, and I'm not sure how many people care that deeply.
Good info, thanks for explaining this clearly and concisely.
No worries, thanks for watching
Best explanation so far in youtube. I was so confused before watching the video. Thanks alot ❤
Very nice demo. Thanks a lot.
Really awesome, sir, is there any video in which u have showed dynamic balancing also?
I don't have anything showing how to achieve dynamic balance, I think you need a pretty specific measuring machine for that.
Great....love it Thanks
This helped me, thank you.
you taught me something today, thanks
Glad to hear you found it useful, thanks!
Again, thank you very much. What is couple imbalance?
Dynamic imbalance = static imbalance + couple imbalance, so if you have a shaft that vibrates when it's rotating, one part of the vibration is caused by static imbalance, one part is caused by dynamic imbalance, and the total imbalance is dynamic imbalance.
I'm not sure if those terms are universal. My analytical mechanics textbook makes no mention of the term "couple imbalance".
@@antalz Thank you. Reading a book written by Ricky Smith and Keith Mobley and it states..."There are four types of imbalance: 1. Static 2. Dynamic 3. Couple and 4. Dynamic imbalance combinations of static and couple.
I appreciate your answer because the differences where not at all clear to me.
@@pkilo2811 Ow that's an engineering book. I find engineers like to define lots of catagories and situations. I was using a physics textbook, they like to define as few things as possible, it's more elegant like that or something. So my textbook only has static and dynamic.
Well done ... Thanks.
Thanks, and you're most welcome!
I've achieve static balance on my tires, but I'm experiencing Dynamic imbalance, and it's driving me nuts!
I think you should ask a mechanic shop about that, that's very difficult to solve without a tire balancing machine. I guess you should add zink weights to the inboard and outboard part of the rim, to create a dynamic imbalance to offset the existing dynaminc imbalance, but how much weight to place where is nearly impossible to figure out without a balancer.
Nice demonstrations pieces, I haven't tried them but your video makes it clear enough that I can imagine holding them in my hands and feeling the results. Well done. In the future if you think one of videos enhances a comment that you are making about something that I've posted, include the URL so that others may more easily find it, always interested in other's opinions
Thank you! I will do so in the future, I thought putting links in comments makes it very likely UA-cam discards the comment as spam.
very educative. Thank you great simulations
I thank you so much for this video. It has greatly helped me understand this concept!
That's great to hear, thanks!
That's the best demonstration of balance I have seen very clear and easy to understand. many thanks.
Thanks, I'm glad it was helpful
Excellent video, the visuals allow for intuitive and rapid understanding. Thanks!
Thank you, I'm glad you enjoyed it!
Nice explanation. Now to my problem: my washing machine goes out of balance on the low speed spin (at the end of the wash and rinse cycles), but not on the high speed spin (occurs twice on the spin cycle). I observe that as the machine spins up the high speed spin (spin cycle), there is an intermediate speed where the machine starts to go out of balance, but the rate of increase in angular velocity fairly rapidly damps that out. On the low speed spin (wash and rinse cycles), the angular velocity seems to terminate right at the point where the out-of-balance condition is at a maximum. It seems to me that, under the imbalance condition, the machine moves from side-to-side rather than at random, and I suspect that this is because the base is narrower in the side-to-side direction than it is in the front-to-back direction. Thus, I believe that the oscillation of the spinning unbalanced wash basket hits a vibrational frequency of the washing machine base causing the machine to make unpleasant noises and to walk around.
The machine is designed with a "balance" ring at the top of the clothes basket that is filled with fluid. I presume that this fluid-filled ring is supposed to dynamically counter any oscillations that result from an imbalanced load in the basket. Inspection of the basket shows that there is fluid in the balance ring and there does not appear to be any damage to the ring that would cause a leak in the balance ring.
I am having a hard time visualizing how a relatively small fluid-filled ring at the top of the wash basket can adequately stabilize an unbalanced load of wet clothing in the bottom of the basket. Alas, for my model, the balance ring cannot be replaced and the cost of a new basket is nearly the same as the price of a new washer.
I should point out that the wash basket, the outer container and the motor and gearing are supported on suspension rods with springs to damp out vibrations. I am thinking that, in addition to springs, the suspension rods should include dashpots to overdamp the motions.
Any thoughts about this practical application of the points made in your video?
BTW, your video was the best I have seen about the subject of instability of rotating systems! Thanks.
Very clear explanation of the subject. Well done
Nice explanation sir.
Great video..... Thanks a lot... 🙏🙏🙏🙏🙏
Thank you!
GRAZIE
Best example on the internet! 👍🤘👏
Looks like dynamic is just 2 plane balance, and that if the wheel rotated on a point instead of an axis you could determine dynamic imbalance using static methods?
Well that's a weird way to think about it honestly. Rotation is usually regarded as being around an axis. Perpendicular to that axis is a plane.
Maybe by "rotated on a point", you mean having the object spinning in free space. In that case the object will always rotate around its center of mass. Another way of looking at dynamic imbalance is that the axis of rotation is not one of the principal axes of the object. I'm not sure if you can measure dynamic imbalance using static methods, I believe not, but honestly this piece of classical mechanics has been ages ago for me.
Actually you are correct, even about a point you couldn't measure dynamic imbalance. For some reason I imagined the bolts sticking out in different axial directions creating a couple in a static scenario, but they only do this in a dynamic scenario where the forces are radially outwards. In a static scenario in a gravitational field they're both 'down' and cancel each others turning effect.
amazingly explained !
Thankyou
Thank you! Awesome presentation.
Thanks a lot sir ✨It helped me a lot
Imbalance is in your checkbook, unbalance is in your rotor.
Thanks mate, I updated title and description but I'm afraid I can't update the video itself.
No worries. Nice video.
great video.
Thanks mate, thanks for watching
nice demonstration. I didn’t know that was called dynamic balance I thought it’s just a way to balance the weel better, but it makes sense since it only occurs when you rotate it. I have a flywheel and it has a counter weight to balance the crankshaft and that means it can’t be balanced dynamically but that’s maybe one reason why the redline is 5500rpm .
That could be, though the flywheel itself should be statically and dynamically balanced. But balancing the crankshaft is very hard. You can look into primary and secondary imbalance, though I'm not very familiar with it myself.
I don't need to 3D print these. I don't have a drill press. I've been bugged by these problems for decades. But not enough to go get a drill press.
A drillpress and 3D printer both aren't too expensive I would say. I think for many the real issue is where to put one.
Hello Antalz, I enjoyed your video a lot, did you create the animation?
Thanks! I'm not sure what you mean, everything shown in the video is my own work, and the files for the 3D printed bits are also my own.
great video. concisely explained
Thank you, thanks for watching
How grooved pulley having keyway balancing done in balancing machine?
Not sure about that honestly, I think people just ignore it. The keyway is close to the axis of rotation, so it generally doesn't create too much imbalance. I don't think people do it for gears either. For when it is done, I don't know exactly how.
We make a half key
Great explanation.....
Thanks mate!
Thank you very much
Thank you for watching
Thanks from Turkey
No problem at all, warmest regards from Dutchman in Austria!
Great video that really explains it. If one has dynamic imbalance how does one know the weight and distance from the center one needs to place it in order to counteract the dynamic imbalance?
That's actually quite tricky. What you can do is put the shaft in a pair of bearing, and then have the bearing housings supported by load cells. In this way you can measure how much force is exerted on the bearings, and by checking whether the force is in the same or opposite direction you can find whether you have static or dynamic imbalance.
You can then run the math backwards to figure out where to place weights, but I haven't studied that math. You will have multiple solutions, you can use lighter weights if you can place them further out.
@@antalz Thanks for that explanation. I am going to try to figure it out.
@@antalz One more question if you don't mind. I am creating a wheel balancer as I need to balance many thousands of wheels. The wheel is 2" wide, 7" in diameter. If I have static imbalance that means I will have to place a weight on each side of the wheel at some distance from the center of rotation, correct? If I also have dynamic imbalance I will have to also place a weight on just one side of the wheel also distance from the center correct?
@@Yoyo-ug7wt Kinda, but you got it backwards. Static imbalance can be fixed with a single weight, dynamic imbalance needs to be fixed with 2 weights. If you try to fix static imbalance with just 1 weight, you und up creating static imbalance which needs a second weight to be fixed.
@@antalz But I am not sticking a weight right through the wheel to the other side like in your video. I can only stick it on one side, the other or both. If the wheel is 2" wide and has static imbalance and my weights do not extend right through the wheel to the other side then I will be creating dynamic imbalance by placing the weight only on one side won't I? My wheels are solid plastic.