Ball Mill 101

[pyrogeorge]

I have another question.

 

In passfire topic for ball mill construction i calculate the speed for my ball mill and it recomended 69rpm as optimal speed and 106 as critical speed.

 

But now my ball mill rotates 95rpm..So,i must reduce it?or is it ok and it will make faster powder(less time) than if it was in 69rpm?

 

sorry for my bad english

[Mumbles]

It will probably take longer to make the same quality BP, as at the optimal speed.

[marks265]

Pyrogeorge,

 

What I have found is that when you spin a jar too fast you can hear the difference in the sound of the jar. I can vary the speed of my motor so I can obtain what is optimal for me. When I first charge my mill and start to spin it, the media has an unbalanced effect. I can hear everything clumping up in the mill, (actually it is noisy than quite alternately). So I start slow and as the material and media mix I begin to speed it up. That is a matter of a minute or two. When everything is evenly mixed I bring up the speed to an approximate 60 rpm on a 6" jar. Then it really starts to sound like a serious machine with the balls constantly rolling. The point is for you to figure out that sweet spot with a fixed speed of course. If you can view the inside of the jar while turning from the side I like to see the top surface of the balls or media at about a 40 degree angle vs level when not moving. I have done this with a clear jar of just media and found my optimal speed based on that. Basically I found that if the jar spins too fast the media and material just flops over on it's self and does not grind. If it is too slow it grinds but takes forever. A constant cascade of media may be a good way to describe this. But to keep the cascade going as fast as possible without centrifugal force coming into play and creating the flopping effect. Another tidbit for you is that I added lift bars 180 degrees apart inside the jar. These help to make sure that nothing in the jar finds a happy spot to lay passively over time.

Hope my 2 cents helps ya!

 

Mark

[pyrogeorge]

It will probably take longer to make the same quality BP, as at the optimal speed.

I have the same thinking..so i will reduce the speed.

 

thanks

[Bender222]

I want to start ball milling. I have lloyd sponenburgh's book aswell as dan william's. I do not have access to any of the tools used to make one of the efficient ball mills they describe. My goal is to eventally construct a mill but i am uncertain when i can. in the meantime i woulod like something that works so I can start perfecting my Bp and experiment with different production techniques and charcoals. I have heard that the harbour frieght tumblers are terrible for ball milling. My intention is to buy one of the 6 lb dual drum tumblers and modify it a little so that its not so terribly. of course it will still never compare to a sponenburgh but it will hold me over until then. My idea is to use electrical tape to enlarge portions of the roller so that it effectively increases the rpm to 90-95 which is optimal for that small jar. id also get 1/2" hardened lead balls and use just one container at a time because with the optimal charge of both media and material it will weigh just over 7lbs and therefore would not stress the cheap motor quite so much. I could then use the second jar as a spare. with such a small jar id only be able to make about 200g at time. while that is a small amount I think it will work out and help me perfect my BP using small amounts of ingredients before I go and make the sponenburgh mill and really start to do it.

A bonus is that I hear the tumblers are alot more quiet to use. With the modifications i should be able to make bp at a reasonable 4 hrs or so instead of the ridiculous amount of time that was needed before. what do you think? Plausible? also how powerful is a 200g BP explosion?

[scarbelly]

I want to start ball milling. I have lloyd sponenburgh's book aswell as dan william's. I do not have access to any of the tools used to make one of the efficient ball mills they describe.

 

Really constructing a ball mill isn't that hard and doesn't require much more than a drill and a screw driver (for tools at least) if you're resourceful. Of course you will need to find bearings, sheaves, and a motor, but that certainly is not too difficult. Any decent hardware store will have bearings and some may have sheaves and drive belts as well. For the sheaves on mine I used the the pulley part of clothespin pulleys (2 different sizes). The motor is probably the hardest part to get. Apparently though, they're pretty easy to get also.

 

A bonus is that I hear the tumblers are alot more quiet to use. With the modifications i should be able to make bp at a reasonable 4 hrs or so instead of the ridiculous amount of time that was needed before.

 

I think the main reason that rock tumblers are quieter is because of the Lortone jars that they use. They are rather soft, and therefore the media collides with the walls more quietly. You can use these on a regular ball mill as well, but if you build your own mill, you will have to buy the Lortone jar seperately. Also note that the lids on these have been known to pop off. Secure them with a little duct tape when using these types of jars and that should do the trick.

 

 

Anyways, good luck.

[Bender222]

So I should just skip tho harbour fright one and start working on trying to make a sponenburgh one ?

[scarbelly]

Not necessarily. I don't know how much a harbor freight one costs but I imagine it's not all that cheap. Building your own is much cheaper, and may result in a better finished product. You don't have to follw the design exactly either, ball mills can be constructed in multiple different ways. If however, you're not all that great with your hands or it will take you a long time to construct one, buying a temporary solution may be the way to go. It all depends on how you feel about it. If you are eager to get into milling and need to start ASAP, you might want the harbor freight mill. If you are in no hurry it might just be better to build your own straight off the bat. However, if you buy one and build one later on, you will have 2 usable mills.

Apologies for the "avoid answering the question" method I took to responding, but it really all depnds on you and what your needs and desires are. I would say weigh out the options and choose whatever makes the most sense to you.

Hope I could be of some help. Good luck!

[Ventsi]

I have the 3lb version , really great in my opinion.

The 6lbers run at 50 bucks, I'd buy it if I were you, the jars themselves are worth 50 bucks, I was amased how quiet they were and with some non-resedue tape they are perfect .

 

Its alot easier than building your own mill. If you make your own wiring the engines is supposed to be a real chore.And there is aligning the rollers to perfection, making jars, etc.. Call me lazy but I'd just go and buy one.

[Seymour]

It depends on what you want your mill to do.

 

I want my mill to churn up a kilo or two of composition.

 

Buying a mill like that is going to cost lots of $$, and shipping it even more."

 

So I built my own.

 

 

If you only want 200g buying one may be easier, depending on where you are, though unless you are careful it may not be up to the abuse us pyro's give them. Make sure you note down what other people bought and use successfully.

 

The boom given of by 200g BP will vary, depending largely on the confinement. A rubber mill with a loosly fitted lid will probably not be too dangerous (unless you are very near), with HDPE barrels quite safe too, though the boom will no doubt be louder!. With materials such as PVC (widely used) or metals (avoid this one) projectiles make the bang in to a bang with teeth.

 

It is common in New Zealand (and no doubt elsewhere) for bored youngsters to empty the lift from bought roman candles in to a plastic bottle, stick a fuse in and make a rumble. For perhaps 20g, these harness the power fairly efficiently, and can set car alarms of many tens of metres away. Consider this an example of the potential, though it may not achieve this if your mill was to explode.

 

However, so long as you make sure you use non-sparking media and barrels, only mill safe-to-mill compositions, and are very careful to avoid contamination (was there a nail in the wood that the charcoal was made from? Did you weigh the sulfur in a container that was used to weigh Titanium?)your mill going up is not likely, but still, its best to plan for the worst.

[Mumbles]

A kilo sized mill runs around $170 in the US.

[TheEskimo]

Hah...I bought one of those 15 pounders of of PyroDirect. A full 175$ US. Works like a champ. Really quiet, and can handle a lot of BP (for my scales of production, I produce about pound loads each batch on a good day. I made my own PVC container, though.)

[pyrogeorge]

Bender try to make one,it isn't so difficult to make one and it will be more efficient than other mill you want to buy.

 

Some photos of my ball mill.

 

http://img13.imageshack.us/img13/8697/dsc02435s.jpg

http://img25.imageshack.us/img25/4537/dsc02425s.jpg

http://img25.imageshack.us/img25/8471/dsc02426t.jpg

http://img37.imageshack.us/img37/5690/dsc02427k.jpg

[pyrogeorge]

Hi,

i want to attach lift bars in my jar for better grinding..has anyone attach lift bars in the jar?i want to know how to.

Thanks

[andyboy]

Buy some handles that you use for kitchen cabinets, drill holes through the jar and countersink them so the screw-heads don't stick out and screw them in place on the inside.

 

The kind on the top is great, you can shorten the legs a bit so they don't stick out that much as well.

 

http://www.clasohlson.se/Archive/Images/Products/Hi/handtag_2008-11-19_092121_534.jpg

[pyrogeorge]

i don't think that metal is good idea.

[pogue1000]

Where do you buy your bearings, pulleys etc from?

Bender try to make one,it isn't so difficult to make one and it will be more efficient than other mill you want to buy.

 

Some photos of my ball mill.

 

http://img13.imageshack.us/img13/8697/dsc02435s.jpg

[pyrogeorge]

i bought it from a store here in Greece..not online Edited October 23, 2009 by pyrogeorge

[Bonny]

i don't think that metal is good idea.

 

 

Look for plastic or brass handles for a safer option. You could also just as easily use strips of plastic (PVC,nylon etc...) and attach as mentioned from the outside, preferably with brass or SS screws.

[Twotails]

or if it couuld be done, "bumps" of hard black rubber (like from a tire, or door seal) Or attach smoothed bumps, like and old music box, so it would hit a line of two bumps, then a line of three, then two, and repeat. it might work. But my mill runs wonderfuly, it gets done in no more then 12 hours, and avareges about 5-7 hours. I normaly let it run 12 anyway.

[Mumbles]

The idea isn't to bounce the balls around or provide a number of spaces to get composition stuck it. It's to in essence create an artificial traction. The idea with ball milling is to get a good cascade of media inside the jar. It "lifts" (get the name now?) the media up the side of the jar to allow a steeper cascade angle which improves efficiency.

[Twotails]

I was thinking of the second part when i wrot the first, what i ment was: "or if it could be done, "strips" of hard black rubber (like from a tire, or door seal)"

 

I ment strips in the first part, not bumps. but i do get what your saying.

[due559]

I'd like to switch from lead media to stainless steel media, but I'm not sure which alloy of SS is suitable.

 

So would the 303, 304, or 316 alloys be spark resistant enough to mill BP?

[Mumbles]

Someone else will have to help out here, but I think all the 300 series stainless steels are adequate. It's the specialized tools to cut and clean the media that I think make people hesitant to use it.

[due559]

Thanx Mumbles, I've read something like that before - just trying to confirm it here. My original plan was to buy a hundred pieces of precut 1/2" x 3/4" 303 SS rod from speedymetals.com and use a bench grinder to remove the sharp edges by hand, not sure if that'll work though.