Ball Mill 101

[tentacles]

Frank: I ran out of stuff to surf here at work, so I thought I'd try and calculate how much power it takes to run a 6" ball mill at 100 RPM... I'm theorizing that a ball mill requires as much power as lifting the entire weight vertically at the surface speed of the inside of the jar.. which is unrealistic, I know. With 32 lbs it comes to 5026.54 pound-feet/min. A horsepower is defined as 32000 pound-feet/min, so 1/6 HP would be perfectly sized for a 6" (1 gallon) mill. Still, a bigger motor can be put to other purposes as well, which is definitely something to consider. One guys star roller also serves as his pig rotisserie!

 

So your 3/4HP motor should be gobs of power for that 8" jar you're planning. Did you want to go and pick up some big PVC for a corning machine? (edit) an 8", 2 gallon jar would need about 1/4 HP (~9000lb/min)

 

My calculations are pretty barbaric, since not all of the media is travelling at the outmost layer in the jar, and some of the media is always tumbling down, but I figure it's more of a worst case scenario, and it ensures your motor has enough power to start up.

[frogy]

Here's the motor I'm using...

 

I just found a lot more information about it

 

http://www.grainger.com/Grainger/items/3M138

 

Shaft Orientation: Parallel

Nameplate RPM: 60

Input HP: 1/10

Gear Ratio: 27:1

Voltage Rating: 115

Overhung Load (Lb.): 150

Full Load Torque (In.-Lbs.): 59

Enclosure: Open

Full Load Amps: 2.6

Thermal Protection: None

Ambient ©: 40

Hz: 60

Phase: 1-Ph

Motor Type: Shaded Pole

 

Nice to know that I got a $80 motor for free

and that it has a 27:1 gear ratio... so it's actual output is 1620 rpm or close.. It says thermal protection none... but the motor doesn't get that hot because it does have a fan built-on blows out the back...

[krackerjack9]

If its a underwater well motor 1.5hp that thing is going to have a TON of torque!!! I used to work on these years ago. the biggest problem I think you would have is that you would need a starting capisistor, 220-240volt power, and something to cool it down, normally these things are surrounded by water to take away the heat they generate. The start up on these is so fast it would do some pretty good damage to your belts or pulley system if you did get it wired up. The motor with the right pump could push water straight up from 500ft in a 1 inch pipe at 12 gallons a minute. I have found that Tread Mill motors are super easy to convert to Ball Mills and have more than enough power to turn a 2 30lb loaded jars. Most can be found on Ebay for less than $45.00 or your local garage sale get the whole tread mill and rig up some rollers to contain the jar on the tread mill and your in business. Very simple very easy and anyone looking at would just think its a tread mill.

[qwezxc12]

I think the only risk of using a Treadmill motor is that they're (correct me if I am wrong) DC and have brushes that can potentially be an ignition source. Perhaps not the BP dust, but possibly acetone or other flammable vapors that might be in your shop.

[frogy]

I think he means just put 2 idle rollers above the tread mill's treads and place your jar in between them...

 

If your going to be milling BP or anything, are you going to carry a few hundred pound treadmill outside? lol

[Mumbles]

I have a 1/2HP motor, that turns out to be a lemon. I'm hoping it's because I don't have enough of a load on it, but it turns off in like 10 seconds after running, like it is popping a circut breaker internally. I got a bigger motor like that because I had aspirations to make this gargantuan 4 jar plus star roller contraption.

[qwezxc12]

I think he means just put 2 idle rollers above the tread mill's treads and place your jar in between them...

 

If your going to be milling BP or anything, are you going to carry a few hundred pound treadmill outside? lol

He also stated, "I have found that Tread Mill motors are super easy to convert to Ball Mills and have more than enough power to turn a 2 30lb loaded jars. Most can be found on Ebay for less than $45.00..." refering to just the motor that could be used to power a mill. Either way, whether the motor is still inside the treadmill or outside running a more conventional type ballmill makes no difference.

 

I offered a cautionary word because some people might be doing various things inside their house/garage/basement like running their ballmill and working with solvents and flamable metal dusts. A DC motor can be a potential source for spark ignition.

[krackerjack9]

Yes you are correct in on a treadmill its self you just put the Jars on the tread and line up your rollers to keep em in place and your good to go.

 

Also a good point on the Brushes being a source of ignition. As far as vapors I dont mill inside a building. I do mine outside in sort of a concrete ball mill bunker. Just more of safety thing sort of over kill on my part. The motor is strong enough to also be used as a Star roller. I use a Serpentine belt and a belt tensioner. I got mine at a junk yard for next to nothing. Old Altenator pulley and power steering pump pulleys are right in the ball park on the ratios. My motor is a good 2 1/2 feet from the jar and a has a seperat compartment or divider in the bunker for it. I have had 2 one gallon jars loaded up on it and no problems. On the ends of my jars I have it reduced down to where you can have a 6in sewer clean out cap the screw out type with the big 2in squared head. I get a very good seal and no leaks. I had to fill in the void from the threads back (inside) to make if flush. Also a bit of sanding on the treads to get it screw in farther. The part I like about tread mill motors is that with the controller you can dail in the correct speed. As with anything use common sense and dont differ from your routine. I have jars just set for only one thing to mill, charcoal,Kno3,sulfur,Klo4,BP only, Potassim benzoate,Klo3, ect.

The divider will keep your fan on the motor from seting up air currents which would and could bring some of the dust that could leak out to the motor brushes.

 

Now just using the tread mill all intact I do know of a person who uses it just the way it was when he got it at a garage sale for $75.00. He found some rollers from the back of a grocery store on a busted up accordian roller rack that one uses to ferry boxes out of truck. He just adapted them and wham bam he was done. Odd looking yes but no one would guess what it is really used for.

[bmarley5780]

not finished but....

[jacob]

You know, i tried to use skateboard trucks on my ballmill but i couldn't get them to line up right and my jar kept sliding off the wheels, maybe it was because mine where used. how many hp is your motor bmarley?

[bmarley5780]

I think it's a 1/3 hp.

 

with the jar sliding off...If you look at the pic -the mill jar lid- you'll see a " stopper " to stop that jar from moving. Its actually a shower curtain ring (holds the curtain to the shower rod). I have them on both sides.

[bmarley5780]

better view

[jacob]

I did see those, nice use of shower rings by the way, i was just too lazy to put jar stops on my mill. i thought that my 1/3 hp motor was too weak, so now i use a 3/4 hp one out of a clothes washer.

[Bonny]

I use a 1075 RPM motor from a barn fan. The main problem is that it is designed to have constant air flow and therefore needs a small fan blowing on it or it will overheat (except in winter up here). The motor was free though... I think it is only 1/15 hp, but works well. It has approx 1-1/4" drive pulley attached to a 5-1/2" pulley to reduce speed. The belting I use is soft,flexible, round orange plastic and is very handy as it can be cut to any length and simply melted together using a propane torch or even a soldering gun. The speed is further reduced by the shaft size (1-1/4") driving 3-5" diameter (empty peanut butter) containers. RPM is a bit fast but seems to work just fine.

[airsoftlife]

nice. dude, i clicked the link in your signature...that is nasty! i almost threw up...yech

[GraafVaag]

Just felt like showing some pics of my ballmill..

(Note, the pic's are hosted on the dutch pyroforum, and then hotlinked.)

 

Just ten days before NYE, my old ballmill broke down. One of the gears turned out to be made of plastic, while the other one was made of steel. I thought they were both made of steel.

This ballmill worked with a 10k RPM motor, on 230v AC. Not a real strong motor, but the speed does it, slowed down well.

 

Anyway, this one's dead now. I couldn't find a new gear. (Interglot says 'gear' is the right word, I'm talking about a round wheel with tands lol)

 

So, I had to build a new BM real fast. (Finally, it took me one day and a half.) Here's the result:

Total Pic

How the motor is slowed down

(Yep, that's a cheap piece of rubber.. I need a new one every +- 15hr)

And last, the ball bearings

I had those lying around somewhere here..

 

Motor voltage is 230v again, 2800 rpm. The jars lie on two 8mm metal threads, which was handy for attaching wheels and bearings. I used shrink tube to give them more grip on the jars.

 

This new ballmill can easily handle two filled jars, containing almost 3kgs of lead, and up to 400g of blackpowder.

 

Happy Milling!

GraafVaag

[TheSidewinder]

Nice, inexpensive Ballmill!

 

Good work!

 

M

[Svarc]

Hi there to all.

Nice topic for new ball mill makers (like me).

I am still confused about some little things about ball mills because I have many faliures on building my own ball mill in my (I rather not say ) years of experience with pyrotechnics so i still make BP with my Hand Ball Mill (just to note that for safty I am not milling mix of chemicals in the hand mill just pure chemicals then i mix them on a sheet of paper) I know that I can't make decent BP with this method so i am collecting as many as I can informations about ball mills so please don't be angry about me asking stuped questions.

 

This is my questions:

 

Which way shoud the main shaft need to rotate (pushing the container down or up) ?

 

How much lead media is the conteiner filled with and how much powder for miling?

 

What diameter should the lead balls be for beter milling?

 

Is it beter to use mixed diameter lead balls or all of them same size (or any other shape like little cylinders) ?

 

What is the min RPM and max RPM of the container for ball mill?

 

Do you put dry mix of chemicals or slightly misted with water for safty?

 

 

 

 

I have searched and doesn't know where to post my questions so if you think that my replay miss the topic just tell me I will edit it or delete it.

Best wishes to all. Svarc

[oskarchem]

1) I don't think it materes which way the contaner goes.

2)If I recall well I think it is 2/3 of the contaner that you fill with media

3)This is a question for wich to awnser we would need to know the size of you contaner

4)Better to use the same size

5)Don't know sorry

6)So since the only comp where you can mix oxidiser with fuel is Black Powder, if I remember well, wetting the mix before putting it in the mill will result ina big ball.

 

BTW: If you cannot build a good enough mill why not just buy one?It's not *SO* expensive I just ordered one from pyrocreations (3lbs for 52$)

[Svarc]

I can't bye one because I can say that i come from black zone country so no internet shoping, no free transferr of money... so bying is out of my reech. Sorry for my bad english.

[GraafVaag]

1) I think that pushing up the barrel needs slightly less power from your motor, but it won't matter much.

2) I usually fill my jar 1/2 full with media. Then the mixture is poured in, and just covers the media.

3) Lead ball diameter doesn't matter that much. In the beginning, I used 25mm glass balls, and now I'm using .530 muzzleloader bullets. (So about 13.5mm) Larger is OK, smaller might be worse.

4) Doesn't matter.

5) Well, my ballmill is currently running 45rpm, which (imho) is too slow. It takes longer to mill meal to the same speed. Better would be above 60rpm. You can go as high as you want, but the lead balls should NOT centrifuge on the jar's walls.

6) Well, that depends on the mixture. I sometimes ballmill my D1 glitter for 5-10 minutes, to get a dense glittertail instead of a random cloud of glitters. This is milled dry off course. On the other side, I add a few drops of water for every 100g meal I mill. (For higher burning rate) Same goes for C8 stars. (However this is to get a better fire dust effect, and not to gain speed)

[Mumbles]

1 It indeed doesn't matter which way the barrel rotates. What is down for one side is up for the other, and vice-versa.

 

2 For optimum efficiency around half full of media, and 1/4 full of composition is ideal,

 

3 The diameter size depends on the diameter of your jar. I use .5" media in a 4" wide jar, and .75" in a 6" jar.

 

4 Some say it is better to use a mix, while some say it's best to use one. Larger media is better at crushing large particles down, but slower at grinding to a powder. The opposite is true with the reverse.

 

5 There is no min rpm, it will just be terribly slow if your jar is moving slowly. The max again depends on your jar diameter and media size. Generally 70-80 rpm is pretty good though. When it moves too fast the media is stuck to the walls of the jar instead of being allowed to tumble.

 

6 I will add a tiny percentage of water when milling to keep the dust down, but not really neccesary or helpful one way or the other.

[Svarc]

Thanks to all for replaying.

I have from 5 to 10 mm in diameter lead balls and some 5mm diameter 10mm long lead cilinders wich I want to use for milling media. And I plan to use 20cm diameter and 40cm long plastic canister. Is this ok?

I have 2KW 1400RPM electric motor from washing machine. Is this enought power?

Does enyone know calculations for puley transmision because I want to make puleys from aluminium and to drop down the RPM to 80RPM?

 

Is the calculations like this: calculating the perimeter of the circle of the puleys like P=2*r*Pi an then devide the biger with smaller P2/P1 and you will find the relation on how faster the smaller pulley will rotate then the bigger puley?

[Svarc]

Sorry to all for being stuped non searching asshole for the last question. I first post the replay and then searched google about pulley calculations and found this site http://www.wfmeyers.com/customer/calculatorPulley.html wich do the work for anyone interested about pulley calculations. Simplies as it can be.

Sorry again.

[Frozentech]

Sorry to all for being stuped non searching asshole for the last question. I first post the replay and then searched google about pulley calculations and found this site http://www.wfmeyers.com/customer/calculatorPulley.html wich do the work for anyone interested about pulley calculations. Simplies as it can be.

Sorry again.

On Passfire, along with a good article on ball mill design, there is a calculator that will take into consideration jar diameter and milling media size to give you optimum and critical rotation speeds. There is also a calculator for drive train design taking into consideration motor RPM, pulley sizes, drive roller sizes, and milling jar O.D. to give the desired rotation speed.

 

Just one of *many* goodies on Passfire. If you like, give me all your data and I will run it through the calculator.