Washing machine - centripetal force

[SentinelAeon]

During summer i wash light items - t-shirts, boxer shorts and low-cut socks, washing machine is just 1/4 full and it cant balance during spin properly. During winter with bigger items there is no such problem.

So i was wondering, could a temporary solution be to just use some kind of basket inside the washing machine that would artificialy make its drum smaller and therefor all clothes would be closer to center of the drum therefor reduce centripetal force ? Can such thing be bought ? Would it even work the way i imagine ? See attached images for more details.

We ignore washing efficiency for now, let's just talk about forces during spin cycle.

 

[Lnewqban]

Centripetal force would be bigger.
It can be done, as long as there is a path for water to drain out to the periphery.

 

[Chestermiller]

During summer i wash light items - t-shirts, boxer shorts and low-cut socks, washing machine is just 1/4 full and it cant balance during spin properly. During winter with bigger items there is no such problem.

So i was wondering, could a temporary solution be to just use some kind of basket inside the washing machine that would artificialy make its drum smaller and therefor all clothes would be closer to center of the drum therefor reduce centripetal force ? Can such thing be bought ? Would it even work the way i imagine ? See attached images for more details.

We ignre washing efficiency for now, let's just talk about forces during spin cycle.

View attachment 332335

Add kitchen towels and bath towels. Dish drying mats.

 

[SentinelAeon]

I already mentioned that people suggest adding towels and that is not a solution for me. If i had dirty towels or other material, i would wash it with my tshirts. But i dont. So if im gonna add clean towels into my washing machine for balance purposes, i might as well go the smarter route and design a removable basket for washing machine, something that is small and wont need drying. Or add some kind of padding to walls of washing machine. See the thing wrapped around the wheels of this truck. I would need something like this, only thicker and obviously something you put inside the drum not around it. But that is where i got my idea.

Resistant foam might not be the worst idea come to think of it. If i made it so that it is the exact right dimension to fill the inner walls of the drum and if it was in one piece, it will be like a very big washing bag. But it will be big enough to hold the walls of the drum and not slip. Foam will absorb water but that is good. Because i will have high mass evenly spread around the walls of the drum. That means that even if light t-shirts and shorts wont be perfectly balanced, their net effect will be lower because bigger mass will be evenly spread.

Im gonna do a test and record it. For science's sake. I dont know why there isnt such a product. For instance, i saw a very neat product for washing shoes in washing machine. Its basicaly a non movable tray to put the shoes on. Well, its strange that they didnt make something similar, like plastic cage instead of plastic tray, that you put into washing machine and its removable. And it would essentialy simulate like you have a smaller drum

 

[JT Smith]

What about affixing dense, non-absorbent weights (metal) around the drum so that the weight of your clothes is insignificant in comparison? That's assuming you can attach something to the drum without too much trouble.

 

[Flyboy]

... Huh. I've only really ever used vertical drum washing machines except at the laundromat. sure, a bunch of towels or something will throw a vertical off enough to make some noise, but I don't know if there's really any "easy" fix for a horizontal drum. It's a matter of how the load settles as it spins up, and there's very little you can do to control that with modifications to the drum.

The problem I see is that they designed the drum's dimensions and speeds to produce the right amount of Gs to pull the water out. Making an insert to reduce that diameter is going to cut into that performance and will leave your clothes wetter when the cycle finishes.

 

[Rive]

...some kind of basket inside the washing machine that would artificialy make its drum smaller and therefor all clothes would be closer to center of the drum therefor reduce centripetal force ?

A lot will depend on the exact machine (since on newer machines balancing is done by tumbling the load a few times left and right to distribute the pieces: and at the beginning of the cycle the load is measured some similar way, so the water level could be adjusted as 'just enough' - these kind of tricks will be most certainly messed up well), but by my suspicion reducing the depth of the drum instead of its radius might work better.

 

[Tom.G]

So if im gonna add clean towels into my washing machine for balance purposes, i might as well go the smarter route and design a removable basket for washing machine,

But you already have the towels, not the removable basket or foam.

(by-the-way, foam falls apart quite easily -- and the tiny pieces are rather difficult to remove before going into a hot clothes dryer.)

 

[sophiecentaur]

Add kitchen towels and bath towels. Dish drying mats.

Buy more underwear and wash less frequently. It's the same thing with dishwashers - you need a lot of plates. But that's off the topic of balance.

We have found that the 'better' washing machines (e.g.Miele) seem to spread the cloths better and my theory is that they tailor the speed-up profile.

 

[Lnewqban]

Im gonna do a test and record it. For science's sake. I dont know why there isnt such a product.

Just an additional idea, which works very well self-balancing motorcycle tires:

https://www.abcbalancingbeads.com/all-you-need-to-know-about-balancing-beads/

 

[sophiecentaur]

I dont know why there isnt such a product.

If you want the machine actually to wash clothes as well as possible, you need a large diameter drum and an unimpeded path to allow clothes to be lifted up and to fall down continuously. So, unless you want to unload wet clothes and then re-load them, you mustn't have your suggested internal frame.
And there is another way, which some machines use. Better machines even recognise dangerous vibrations, stop, to allow re-arrangement of the load and re-start the spinning process.

 

[JT Smith]

Why not just buy a new washing machine? Our 30 year old machine would get go "tilt" sometimes trying to spin smaller loads but the new one just doesn't seem to care. Big load, small load, it's all the same. I can wash a single pair of underpants if I want. And it knows to use less water without my having to tell it.

 

[jack action]

So if im gonna add clean towels into my washing machine for balance purposes, i might as well go the smarter route and design a removable basket for washing machine, something that is small and wont need drying.

I don't understand why you would consider adding a piece of foam and not some old raggedy towels or shirts - both being materials that would need drying after use - the latter being a method already being tested and proven.

The basket might not need drying but it seems to be a pain to install, remove, and store after use.

And the raggedy towels don't even have to be dried; just hang them somewhere (maybe even outside) and they will dry by themselves until the next wash.

 

[SentinelAeon]

What about affixing dense, non-absorbent weights (metal) around the drum so that the weight of your clothes is insignificant in comparison? That's assuming you can attach something to the drum without too much trouble.

Ty for your reply ! Yes. That was the idea behind resistant foam i mentioned (some people failed to notice resistant, which can also mean foam covered in resistant material). Only difference is that foam will lose its weight after the spin cycle starts. Also weights would take a lot less space. That is where foam would be better - reducing the volume of the drum. But weight itself is probably more important. Attaching would be no problem. And it would have to be such that it can be removed when during summer i wash heavy loads, like once a month. Its a nice idea.

Just an additional idea, which works very well self-balancing motorcycle tires:

https://www.abcbalancingbeads.com/all-you-need-to-know-about-balancing-beads/

Thats a really interesting idea. Might be a bit complicated with a washing machine since you would have to make a second wall inside a drum, though that would also solve the radius thing. But i will keep that in mind and if nothing else, test the product on a motorbike. Those static weights on a wheel only help for a while.

A lot will depend on the exact machine (since on newer machines balancing is done by tumbling the load a few times left and right to distribute the pieces: and at the beginning of the cycle the load is measured some similar way, so the water level could be adjusted as 'just enough' - these kind of tricks will be most certainly messed up well), but by my suspicion reducing the depth of the drum instead of its radius might work better.

Talking about front loading machine, right ? If i understand that correctly reducing the depth could potentialy improve the situation by forcing the machine to balance the clothes easier since there is less space to fill ? Or would the fact that clothes are closer to the point where force is applied to the drum help also ?

Few side notes:
The washing machine in question is quite old, better ones are given away for free. That is why i am using this washing machine to learn as much as i can and modifying it does no real damage. I wear protection gear during tests, stand at a safe distance with on/off switch in my hand and always have a recording stand running incase something goes wrong, i get an entertaining video.

Now, this wasn't a topic to be talked about but i will clarify a few things anyway. First, this washing machine by default is very rough for my taste. Even the gentlest normal program is beating the clothes way to much. I never have stained clothes - i only need to remove sweat. That is why i use a handwash program which tumbles a few times, then leaves the clothes in soapy water, then tumbles some more and so on. It is very gentle. It also uses more water (we have practicaly free water) and only spins once at the end. Clothes are washed perfectly clean. I only use more rough programs when washing bedding, towels and the like. But that is about once or twice a month.

If smaller radius resulted in wetter clothes this is not a problem. My clothes drying stand has a big fan with variable rpm attached to it so it takes a few dozen minutes for clothes to dry depending on how wet they are, the moist air goes through the existing ventilation system out of the house. I am just in the process of adding a few sensors that will detect air humidity between clothes and act accordingly regarding fan speed and possibly heater strength.

______Thank you to those giving some interesting ideas. Often, when asking a theoretical question i get suggestions to buy something or use existing solutions. We are all different. Some of us really like to try new things, experiment, if things go well, great, if it fails, we learn something in the process and we tried something new. To me, buying something is the absolute last resort. Not because i didnt have enough money or i was cheap, but because making something with my hands gives me a lot more pleasure. It is my hobby. Some people like to watch reality show on tv in their spare time. I like to spend my time in my workshop making things and learning along the way. So to be perfectly honest with you, i dont even care about my clothes or the washing machine having difficulty balancing sometimes. I will run this thing until the drum physicaly leaves the washing machine enclosure, in full protection gear and recording if need be. But i am actualy interested in how all those suggestions some members gave me would affect the washing machine. Would adding weights to the drum mean its running the same ? Would it actualy balance better ? Would it break off the shaft ? I thought physics forum was the right place for those questions, but i guess some DIY forum would be a better place ?

 

[sophiecentaur]

Or would the fact that clothes are closer to the point where force is applied to the drum help also ?

For the highest force for shedding the water, the radius of rotation needs to be highest. There is no real substitute for making an even distribution around the periphery and from front to back. Only a cleverer machine than yours can achieve this on such a light load - but just to use more load. Like I said earlier. More underwear. Cheaper than a new machine and they will all last four times as long. Double whammy.

Edit: PS Looks like you're gonna need a bigger sock drawer.

 

[SentinelAeon]

For the highest force for shedding the water, the radius of rotation needs to be highest. There is no real substitute for making an even distribution around the periphery and from front to back. Only a cleverer machine than yours can achieve this on such a light load - but just to use more load. Like I said earlier. More underwear. Cheaper than a new machine and they will all last four times as long. Double whammy.

I agree that more underwear is always better. But to stay on topic, i humbly disagree about the balancing and please correct me if i am wrong.

Let's take 2 hypothetical scenarios. We have 3 pieces of underwear (hypotethical). And we have a washing machine with a tiny drum, maybe something dwarfs would use. If we stretch those 3 pieces of underwear along the wall of the drum, they cover it completely and we have a balanced load. Now lets take another extreme (hypotethical). We have a huge washing machine, something that giants would use. It would be very hard to balance the load with only 3 pieces of underwear since they would need to be spread at exactly same distance from eachother. And also, even if the tiny drum was unbalanced, it probably wouldnt make much difference. But the big drum would spin very violently due to distance of wet underwear from the center. As far as physics goes, is that correct ?

 

[sophiecentaur]

. But the big drum would spin very violently.

Only if the load were more than the system is designed for. Also, the tiny drum would need to spin faster by the square of the ratio of radii. And a small drum would be useless for tumble washing, which relies on dropping the clothes repeatedly by nearly the diameter of the drum. A very full washing machine washes very badly.

Is the drum bearing tight enough or is the damping shot? I have a Miele machine and even that required new dampers last year, after more than fifteen years. Get yourself an on-line repair manual and DIY the job.

I really don't see any workable modification for your machine so more underwear or a new machine are you only practical solutions.

 

[SentinelAeon]

Only if the load were more than the system is designed for. Also, the tiny drum would need to spin faster by the square of the ratio of radii. And a small drum would be useless for tumble washing, which relies on dropping the clothes repeatedly by nearly the diameter of the drum. A very full washing machine washes very badly.

Is the drum bearing tight enough or is the damping shot? I have a Miele machine and even that required new dampers last year, after more than fifteen years. Get yourself an on-line repair manual and DIY the job.

I really don't see any workable modification for your machine so more underwear or a new machine are you only practical solutions.

It is amazing how persistent you are about me buying a new washing machine. How about this, i go and buy a top of the line washing machine, the most expensive one i can find. Will then we be able to continue this conversation, as far as physics goes ?

Again, i am not interested in how efficiently the washing machine would wash the clothes and dry them. That is a separate matter. What i am interested in is how the forces will compare. That is why i gave 2 imaginary examples. I made a mistake of not stating that the speed of small and big washing machine are the same, otherwise the example makes no sense obviously, forces of small machine at 20.000rpm will obviously be bigger than forces of big washing machine at 5rpm. But i am pretty sure my assumption is correct. I will carry out the experiment and see if i am indeed correct or not :)

 

[sophiecentaur]

Will then we be able to continue this conversation, as far as physics goes ?

So you want to know what bearing forces there are on a rotating hollow cylinder with a mass on the periphery? You have a large mass and a small mass - so you can work out where the CM of the two masses lies. It will be near the axis. You then need to find the force needed to keep the (now off-centre) CM rotating around the axis at a given angular velocity.
This force needs to be balanced by the mounting, which will be a pair (or more) springs and dampers. There will also be a concrete mass to restrain the machine from jumping up and down.

All we need now is some numbers for all those quantities.
Is that more like what you had in mind?

 

[SentinelAeon]

So you want to know what bearing forces there are on a rotating hollow cylinder with a mass on the periphery? You have a large mass and a small mass - so you can work out where the CM of the two masses lies. It will be near the axis. You then need to find the force needed to keep the (now off-centre) CM rotating around the axis at a given angular velocity.
This force needs to be balanced by the mounting, which will be a pair (or more) springs and dampers. There will also be a concrete mass to restrain the machine from jumping up and down.

All we need now is some numbers for all those quantities.
Is that more like what you had in mind?

Exactly. Thank you ! So now lets take this problem that the internet is full of - a gal needs to wash just 1 pair of jeans and has nothing else to put into the drum. Obviously if she puts only the jeans in the result will be bad. If its a new machine, it will refuse to spin. If its an old machine, it will do the harlem dance. And there will be some washing machines that will wash nicely but i dont have even the slightest interest in those.

Now. Let us say we would have some way to keep the jeans to the exact center of the drum. And the water would be high enough to reach them. And the gal also had some other means to dry the jeans afterwards with a click of a button so it wouldnt matter that the jeans were still soaking wet after the spin. And also the jeans were only sweaty so there wouldn't need to be much movement in a drum to get them nice and clean. So here it goes. Would the fact that those jeans are at the exact middle of the drum, mean that drum would spin nicely because the load would practicaly be balanced already - balanced at the exact center of the drum?

 

[Tom.G]

Would the fact that those jeans are at the exact middle of the drum, mean that drum would spin nicely because the load would practicaly be balanced already - balanced at the exact center of the drum?

Yup.

A minor detail though is that there won't be much water removed from the jeans because they are not subject to any centrifugal force.

...some other means to dry the jeans afterwards...

Since it's not doing anything, you could also save a little energy by eliminating the spin cycle altogether.

Please try to think things thru, as opposed to impractical ideas to 'win' a 'discussion.'

 

[Rive]

Talking about front loading machine, right ?

Yes.

If i understand that correctly reducing the depth could potentialy improve the situation by forcing the machine to balance the clothes easier since there is less space to fill ?

Yes. If you have - example! - 25cm deep drum those few socks 'n stuff will be just lie on the bottom, far from the axle: with reducing the drum to 15cm depth, they will start to fill up the remaining space and will be closer to the expected 'full' state.

Or would the fact that clothes are closer to the point where force is applied to the drum help also ?

I'm not sure about that. Maybe a bit less torque on the bearings, but honestly, it would require lot more thinking than what I have in me right now

 

[sophiecentaur]

Exactly. Thank you ! So now lets take this problem that the internet is full of - a gal needs to wash just 1 pair of jeans and has nothing else to put into the drum. Obviously if she puts only the jeans in the result will be bad. If its a new machine, it will refuse to spin. If its an old machine, it will do the harlem dance. And there will be some washing machines that will wash nicely but i dont have even the slightest interest in those.

Now. Let us say we would have some way to keep the jeans to the exact center of the drum. And the water would be high enough to reach them. And the gal also had some other means to dry the jeans afterwards with a click of a button so it wouldnt matter that the jeans were still soaking wet after the spin. And also the jeans were only sweaty so there wouldn't need to be much movement in a drum to get them nice and clean. So here it goes. Would the fact that those jeans are at the exact middle of the drum, mean that drum would spin nicely because the load would practicaly be balanced already - balanced at the exact center of the drum?

View attachment 332397

You seem to have demonstrated that you have neither grasped the way a spinner dries clothes nor the way a washer washes them. IS there any hope for you - or your underwear?

 

[Nik_2213]

I specifically got a machine that had a wash cycle with slow 'default' spin speed, plus manually selected, 'drain', 'slow' and 'fast' spin cycles.
Beyond mitigating wash-cycle 'dancing' instabilities, due either light or large loads, it meant that I could give large loads a second slow spin before cranking up the revs...

 

[sophiecentaur]

I specifically got a machine that had a wash cycle with slow 'default' spin speed, plus manually selected, 'drain', 'slow' and 'fast' spin cycles.
Beyond mitigating wash-cycle 'dancing' instabilities, due either light or large loads, it meant that I could give large loads a second slow spin before cranking up the revs...

The smarter machines can do a lot if this on their own. They restrict the spin speed if vibratiobn is a problem and will often stop, rotate to re-distribute and restart the spinning. Our high end machine seems to behave pretty well in this respect.
Note: trying to exceed the maximum load instructions can give you problems. Best to err on the light side, perhaps but there are green issues with this approach.

 

[Nik_2213]

"...but there are green issues with this approach."
Agreed.
Even with a 'Light Load' option, you get the 'Borrowed Armour' effect, always 'Too Big' and/or 'Too Small'...