# small ball mill



## ilikesilver (Aug 15, 2013)

does anyone have a good set of plans for a small home made ball mill, something i can possibly run off of a drill. tim


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## rusty (Aug 15, 2013)

You may want to rethink the type of motor you intend to use to drive this ball mill, drill motors are not intended for prolonged use, the motor would heat up and eventually burn out

Now a days, in almost every applications, electric motors are used, and to control them electrical drives are employed. But the operating time for all motors are not the same. Some of the motors runs all the time, and some of the motor’s run time is shorter than the rest period. Depending on this, concept of motor duty class is introduced and on the basis of this duty cycles of the motor can be divided in eight categories such as 

i.	Continuous duty 

ii.	Short time duty 

iii.	Intermittent periodic duty 

iv.	Intermittent periodic duty with starting 

v.	Intermittent periodic duty with starting and braking 

vi.	Continuous duty with intermittent periodic loading 

vii.	Continuous duty with starting and braking 

viii.	Continuous duty with periodic speed changes 

*Continuous duty: *This duty denotes that, the motor is running long enough & the motor temperature reaches the steady state value. These motors are used in Paper mill drives, Compressors, Conveyors etc.

Short time duty: In these motors, the time of operation is very low and the heating time is much lower than the cooling time. So, the motor cooks off to ambient temperature before operating again. These motors are used in crane drives, drives for house hold appliances, valve drives etc.

*Intermittent periodic duty:* Here the motor operates for some time and then there is rest period. In both cases, the time is insufficient to raise the temperature to steady state value or cool it off to ambient temperature. This is seen at press and drilling machine drives.

*Intermittent period duty with starting: *In this type of duty, there is a period of starting, which cannot be ignored and there is a heat loss at that time. After that there is running period and rest period which are not adequate to attain the steady state temperatures. This motor duty class is widely used in metal cutting and drilling tool drives, mine hoist etc.

*Intermittent periodic duty with starting and braking:* In this type of drives, heat loss during starting and braking cannot be ignored. So, the corresponding periods are starting period, operating period, braking period and resting period, but all the periods are too short to attain the respective steady state temperatures, these techniques are used in Billet mill drive, manipulator drive, mine hoist etc.

*Continuous duty with intermittent periodic loading :* In this type of motor duty, everything is same as the periodic duty but here a no load running period is occured instead of the rest period. Pressing, cutting are the examples of this system.
Continuous duty with starting and braking: f this system.

*Continuous duty with periodic speed changes:* In this type of motor duty, there are different running periods at different loads and speeds. But there is no rest period and all the periods are too short to attain the steady state temperatures.


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## etack (Aug 15, 2013)

also a three phase motor with a 110V variable speed drive would be the simplest you could the change the drum size with out re-gearing.

For small amount I was told about planetary ball mills they are kind of expensive though.



Eric


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## NobleMetalWorks (Aug 15, 2013)

I bought my small ball mil for $250.00

You can find them fairly cheap if you just look around.

Scott


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## chlaurite (Aug 15, 2013)

Just as a really really cheap example of a near-continuous duty motor - A 20" window box fan. I've used these for a million low-load projects around the house, they work _beautifully_! Best of all, as cheap as they come, you don't even need to buy them yourself because they tend to clog with dust and people throw them out (if they didn't actually burn out the motor trying to make it work, just pop off the blades, rinse out the motor with a good strong spray from a garden hose, dry it thoroughly, oil the bearings, and consider it as good as new). But if you need to buy one, hey, $9.99 at Wallyworld. 8) 

Chop the outer half of the blades off (80% of the normal "load" comes from the outer half, but the inner half moves enough air to cool the motor), making sure they balance when you finish. Affix a shaft extension to the motor (this can work very easily if it has a rear stub of the shaft sticking out, or really really hard if you need to find a way to attach it to the blade hub). Run it to a small pulley, with a belt to a large pulley (with the size ratio corresponding to the speed you want at the output), which connects to your ball mill.

Make sure the mill turns fairly easily - A box fan can run forever, but really doesn't expect much of a load on it. I would recommend measuring its wattage (with a Kill-A-Watt meter or similar) at each speed before chopping off the blades, and make sure you stay *below* that on your final hacked-up device.


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## Jimmy (Aug 15, 2013)

How big?
If small, you cant beat the price of the harbor freight tumbler. On sale right now for $39
http://www.harborfreight.com/3-lb-rotary-rock-tumbler-67631.html


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## AndyWilliams (Aug 15, 2013)

Jimmy said:


> How big?
> If small, you cant beat the price of the harbor freight tumbler. On sale right now for $39
> http://www.harborfreight.com/3-lb-rotary-rock-tumbler-67631.html



Take another $8 off with this code:

86016457


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## Clneal2003 (Jul 15, 2014)

Jimmy said:


> How big?
> If small, you cant beat the price of the harbor freight tumbler. On sale right now for $39
> http://www.harborfreight.com/3-lb-rotary-rock-tumbler-67631.html




Clarification...

Are ball mills used only for ore or can they be used to pulverize karat jewelry?


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## 4metals (Jul 15, 2014)

And what purpose would pulverizing karat serve?


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## g_axelsson (Jul 16, 2014)

Clneal2003 said:


> Jimmy said:
> 
> 
> > How big?
> ...


That's a rock tumbler and not a ball mill. works in two totally different ways.
- Ball mill : crushing
- Rock tumbler : abrasion

Göran


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## rickbb (Jul 16, 2014)

There are lots of people selling those craft/toy type rock tumblers on the internet as ball mills. 

I have one from when my kids were younger and have tried it on some flat packs. It does not work as a crusher, polisher yes, crusher no.

Does not turn fast enough to get the balls to drop on the stuff you want crushed. It just rolls the contents around together. And it's easy to put too much in them and stop them from turning at all.

Look on the home re-loaders forums they have many plans for small ball mills for milling the contents of black powder, etc.


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## Clneal2003 (Jul 16, 2014)

4metals said:


> And what purpose would pulverizing karat serve?



I was trying to find equivalent "rollers that Hoke keeps referring to and most of the threads on here come back to ball mills no tumblers. Last time I tried to hammer a karat gold flat it shot off my metal work bench and across the garage.


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## butcher (Jul 17, 2014)

Jewelers roll gold to flatten it, or make it thinner, wider and longer, or in other types of rollers to make wire... 

Gold can be work hardened, or hardened with added metals, the gold can also be annealed (softened) with a heat treatment, making it easier to roll or work.


Karat gold will be much harder than pure gold which s very soft, hard gold can also become brittle and crack or break more easily under the hammer or rollers, or when worked.
Some metals like lead when melted with gold will make it very brittle.

During the working of gold, under the hammer or rolling, (which can harden even the more purer soft gold), the gold may need to be softened again by annealing to continue to work the gold.

Here is a place you may be able find some help with your question, of jewelers supply's and the processes they use, they have some good info on their web site. Spend a little time looking around their site, they have several good tidbits of information, which is helpful, I have ordered some supply’s from Lacy West, and was very pleased with them, their prices and products.

http://www.lacywest.com/

The ball mill is not what your looking for, or would be no help, unless the goal is to plate the ball mill and balls with powdered gold smashed into, or on its metal surface.


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