colniko Posted June 11, 2008 Posted June 11, 2008 Well, I was planning on purchasing one of the 6lb ball mills advertised on northstarpyro, however, I wanted to see what everyones opinion was on ball mills. I am not going to make my own. I would prefer to purchase one. Initially I figured it to be a no-brainer but noticed on another post someone mentioned that rock tumbler types were crap. So balancing the fine line of cost vs. function, what is a good ball mill for the amateur? Thanks in advance for any info.
tentacles Posted June 11, 2008 Posted June 11, 2008 There's a guy on passfire selling fantastic mills. There is no substitute for a quality mill in pyro - and if you get a small one you will always regret not getting a bigger one. Most here would suggest making your own, if you're any good with tools. If you're not, you do NOT belong in pyro! If price/cost is a big concern (and your budget doesn't run to around $260) then you will have to scrounge and make your own. If you want to buy one of these (they can handle up to a 12" jar/tire) get a passfire account, or initiate a trial and ask about Danny's mills. Here's a pic of his mill:http://www.pyrobin.com/files/ball%20mill%20top.jpg
colniko Posted June 14, 2008 Author Posted June 14, 2008 Well, first off, I am NOT great with tools. I can get by, but definitely not great with them. And I probably qualify more than most to play with pyro ;-) That mill looks solid. I will definitely look into it if you say they are of good quality. Thanks for the response and information.
TheSidewinder Posted June 14, 2008 Posted June 14, 2008 A top-of-the-line Rock Tumbler, such as a Lortone brand, will serve well enough. The milling times will be a LOT longer, though. I use a QT-66 and find I need 24 hour mill times to produce the best BP for lift. I can produce good BP for priming and star formulas in about 12 hours.
Swede Posted June 14, 2008 Posted June 14, 2008 I bought a ball mill, the small one, from eBayer hobfir. It's as good a mill for $170 as possible. For a really serious hobbyist, I'd consider the size larger, but for starters, I'm happy with the small one. DO NOT buy jars, you can make them easily from PVC components from Home Depot or other big box stores.
WarezWally Posted June 14, 2008 Posted June 14, 2008 I would have to say the hexi ones firefox sells. Hexi barrels are much better imo. http://firefox-fx.com/tooling.htm 15 lb tumbler - steel barrel - $172.50
Mumbles Posted June 14, 2008 Posted June 14, 2008 Those are thumblers tumblers model ball mills. You can find them a tad cheaper. I don't know what kind of rpm they run at though, They may still be a rock tumber and not a ball mill, while the ones from hobby fireworks are known to be good speed and quality. You could always get additional hex barrels. [edit] I have heard that the hex barrels run best at slower rpm. around 35 or 40 for this size so speed may not matter.
Sylar Posted June 14, 2008 Posted June 14, 2008 I stand by the opinion that a directly driven mill jar is the best option by far. All you need are the following:-a DC motor with an adjustable power supply or an AC motor with frequency drive-a gear box with about a 8 to 1 ratio (to get rpm in the right ballpark)-a jar grabbing coupling (much like a lathe's claws) Mount all this together and you'll get the most reliable and efficient milling setup, as you can choose the mill jar rpm by either changing the voltage or adjusting the frequency. No slipping of the jar, or it sliding down the rolllers. No belts that wear down every so often. All moving parts nicely aligned to each other with proper bearings from the gear box. Optimal rpm's for every mill jar can be calculated and set.
tentacles Posted June 14, 2008 Posted June 14, 2008 Sylar: The repeated impacts of the media would destroy anything less than a locked in grip. A lathe chuck wouldn't be able to hold a jar very long unless you had pins through the jaws into holes in the jar. Even, then, it'd just beat the plastic to death. Think about my situation: 45lbs of stainless media dumping down nearly twice a second, the jar wouldn't be able to handle that without solid support under it. Then you might have problems with the driving shaft flexing and absorbing some of the impact energy (the milling action!). Why reinvent the ball mill? The closest thing to what you're proposing is a cement mixer mill, but I'm not sure they spin fast enough 'stock' to have a good grinding action. And let's face it: most of us don't make BP in batches that big. Did you look at the picture I linked to? Those mills are about as directly driven as can be, using a conveyor roller motor. The motor is inside one of those conveyor rollers and uses a DC brushless motor with speed control. They're very well designed, the guy selling them got a great deal on the rollers and power supplies or they'd be more like $500.
Sylar Posted June 14, 2008 Posted June 14, 2008 Yes, I saw that picture, and I have no doubt that that is a very high quality mill. I just wanted to throw my method out there for all home builders that don't have the luxury of getting one of those shipped to their doorstep. And as a matter of fact, it does work very well. A lock in of the jar is needed, but it doesn't need to be very tight. PVC lasts just as long as in classic ball mill designs, but I use a stainless steel mill jar personally. It's also easier to powder metals in combination with hard media.
Bonny Posted June 15, 2008 Posted June 15, 2008 Building a ball mill is still the best route IMO. I built one 3years ago when I knew pretty much nothing. It has now been "converted" to also roll stars. As you can se it was slapped together using scrap wood,plywood,rollers from an old printer etc... The motor does need a fan to cool it as it was a barn fan motor in a past life. It may look like junk, but it has been pounding out BP and grinding stuff for 3 years.
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