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Author: Subject: ball mill question
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[*] posted on 2-3-2016 at 01:38

Could you use electric kitchen stirrer or just about any power kitchenware? Some of them have very low rotation ratios, for ex. I just obtained a stirrer that has 450W motor and five speeds.

A tip too, for those who dont have access to lathe and other tools, find a 3D printing supply and order a bunch of PLA or nylon gears, either common reduction setup or for higher speed motors a worm gear that allows huge reduction ratios, allowing the use of even very small motors, reducing noise and electric cost(as it would matter in non-production use anyways). Worm gears are very good for three-phase motors like those found on most drill presses and these motors are usually designed to be run for thousands of hours under load non-stop. On the other hand, you can also design and order a housing for your gears so you can just bolt em up, connect to the motor and rock'n'roll your balls.

Universal motors are way too fast and noisy for ball mill, even if you were able to reduce the speed with worm gear. It would sound a bit like vacuum. Second to that, as long as your ball mill construction is not rigid enough, it will rattle and chatter the more speed you push to it and the less the parts are perfectly balanced.

Adding a good fan to the motor will increase the lifetime to a huge degree. Small line fans, like 120mm that push something 30-150m3/h of air will keep normal 100-300w drill press motors cool. I use one on my customised X3 milling machine main stepper which gets hot to touch when I drive it on large bits for longer periods of time. I used a 3kW welding transformer that had duty cycle something like 10-20% at full power for days with a line fan I got from my pothead friend that pushed mere 1000m3/h of air - it was enough to keep the tranny cool to touch.

[Edited on 2-3-2016 by testimento]
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[*] posted on 2-3-2016 at 02:30

Quote: Originally posted by ecos  
I think dryers and washing machines motors are not designed to work for 11 days continuously without stop!

in their work , they run for certain point then stop again and so on, this is not as stressful as running for days without stop.

I am thinking that a fan motor or air pump motor will be the best solution since their normal work is to run for long time !

I am still thinking about better solution !


Yes the poor endurance of modern white goods worries me. Hopefully my dryer motor will not over heat as it should be rated continuously given it probably had up to two hours on the timer and will not be tumbling 10kg of clothes. The lack of stopping and starting in my application my help increase its life

The motor in the pic I posted above did not have sealed bearing. The bearing on the rusty shaft is worn out (noisy and excessive play probably caused the rusting. The cost of replacement sealed bearings may induce me to get an other. motor.
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National Hazard

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[*] posted on 2-3-2016 at 03:02

I forgot to mention this about universal motors (washing machines)


A negative aspect is the maintenance and short life problems caused by the commutator, as well as electromagnetic interference (EMI) issues due to any sparking. Because of the relatively high maintenance commutator brushes, universal motors are best-suited for devices such as food mixers and power tools which are used only intermittently, and often have high starting-torque demands.

Thats why universal motors are not suitable for ball mills

I wish I can build professional ball mill like this :

Capture.JPG - 34kB

I think he use 24v or 12v DC motor. I wounder how long can it run !

I am trying to search for DC motors as well since they have strong starting torque and speed can be controlled easily.

@testimento, kitchen stirrer !!
kitchen stirrer maybe be good but I don't know how long they can run :)
I will keep this in mind

[Edited on 2-3-2016 by ecos]

[Edited on 2-3-2016 by ecos]
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PHILOU Zrealone
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[*] posted on 3-3-2016 at 14:04

Maybe the good old eolian power could be used to provide spinning energy to pulleys activating the ball mill...
--> Wind ball mill
You know like those advertiser pannel (based on S shape from above) along roads that spins on itself no mather where the wind blows from.
So the only thing is to convert vertical axis rotation to a perpendicular horizontal rotation for the ball-mill...

If there is too much wind, there exist dynamic systems that increases inertia of the system and thus reduces the speed...based on the centrifugal force of 2 weights and the attracting force of springs attaching those two opposite weights to the rotating axis...

PH Z (PHILOU Zrealone)

"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Hennig Brand
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[*] posted on 4-3-2016 at 06:26

Ecos, it is easy enough to get some pillow block bearings. Not sure if these are the best bearings for you, but it gives you an idea anyway.

The frame is fairly simple and could be easily made from some scrap materials even. The motor could be the expensive component, especially if you aren't careful. It is nice that the motor in the YouTube video is so small and fits underneath the drum, but it really doesn't have to and if it wasn't required it would make motor selection much easier probably. Most places I have been, with even fairly modest population size, have motor shops. Often times second hand motors can be found too for good prices, especially at salvage shops (even the ones that don't specialize in motors). All motors eventually wear out, or need to be refurbished, so you have to figure out what is available to you and then what gives you the best value. Maybe you can get motors that only last a few months, or less, but they are really cheap or free. It might make sense to go through several dirt cheap or free motors, if you have a convenient source, rather than spend hundreds of dollars on one top of the line specialty motor. It depends what is important to you.

"A risk-free world is a very dull world, one from which we are apt to learn little of consequence." -Geerat Vermeij
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