Mumbles Posted January 14, 2008 Posted January 14, 2008 That media will likely be too small for that large of a jar. I'd use media up around 18mm or so in diameter. That jar will probably mill around 3000g at a time. Are you sure you need that much? The motor will probably be fine. Given the size of jar and media size, the optimal speed is around 65rpm. The formula for critical speed is (265.45)/sqrt(jar ID - Media diameter) The optimal speed is 65% of the critical speed. The critical speed is the speed where the media will be stuck to the walls of the jar instead of cascading like we want.
Svarc Posted January 14, 2008 Posted January 14, 2008 Thanks to all. And Frozentech I have visited the old Passfire web site in the past but then it have verry litlle info but the new one thanks for reminding me to visit it have quite big resources and info. I will now stop bothering you all, and go to build my ball mill so i will post new thread for it if it is allowed. Thanks to all aggain and Best wishes to all.
Svarc Posted January 14, 2008 Posted January 14, 2008 Dunno Mumbles I really don't need 3000g at one bunch i only need about 100-300g at a time. 3000g is way off my limit. So i will use some smaller canister. Thanks.
FrankRizzo Posted January 14, 2008 Posted January 14, 2008 Lloyd Sponenburgh, the guy who wrote a book on hobbiest ball milling, recommends that the driving roller turn in the direction that *lifts* the milling jar. This helps to avoid jar slippage on the rollers.
nick2354 Posted February 10, 2008 Posted February 10, 2008 I have built a ball mill (with alot of help) it turns at 85 rpm. It is filled about 1/7 full of lead and 1/7 full of black powder in standard ratios. It is now finally powdered and it is a light grey colour when it burns it burns very slowly not giving off much gas but leaving lots of yellow residue. It has been truning for about a 12 hours and shows no sign of improving Note: I did have some water in there, maybe it displaced some KNO3? Has anyone had a similar problem?
TheSidewinder Posted February 10, 2008 Posted February 10, 2008 Im not the ball mill expert here, but I think you're way underloading the barrel. I'm pretty sure you need more lead media and more powder.
nick2354 Posted February 10, 2008 Posted February 10, 2008 Yes, I know the jar should be half full of lead media and 1 quater full of compostion. But I have started off using only little amounts, to see if my ball mill works. The main problem is the residue and why it burns so slowly even though it is finally ground.
TheSidewinder Posted February 10, 2008 Posted February 10, 2008 Sorry if this seems obvious, but you *DID* measure your components by weight and not volume, right? i.e.750 grams KNO3150 grams C100 grams S And not something like7.5 cups KNO31.5 cups C1 cup S Even greenmix shouldn't leave THAT much reside, and will burn ok, though slowly.
nick2354 Posted February 10, 2008 Posted February 10, 2008 Yes, I measured by weight with my 0.1 gram accurate scales. I did cast my own lead and it may have been contaiminated with little amounts of concrete. Would that make it leave yellow residue? If anyone has any ideas please speak up
Mumbles Posted February 10, 2008 Posted February 10, 2008 My best theory is that it's still wet. If it's still wet, it will burn much slower and possibly produce more residue.
nick2354 Posted February 11, 2008 Posted February 11, 2008 I tested it dry and it still burnt slow with lots of residue. I may try milling in another bottle to see if the plastic was contaminating it. I will edit this post and let you know what happens. EDIT: I tryed it in another bottle and it worked fine and then I tryed in the same bottle and it worked fine. My bet is this asshole I know (My brother)put some shit in it.
andyboy Posted February 8, 2009 Posted February 8, 2009 Ellinas Ise? Looks nice although I think your jar will wear out rather fast since it looks like the walls are pretty thin. Good job.
pyrogeorge Posted February 8, 2009 Posted February 8, 2009 Ellinas Ise? Looks nice although I think your jar will wear out rather fast since it looks like the walls are pretty thin. Good job.Yes,ellinas..and you??? No i haven't any problem with my jar
pyrogeorge Posted July 11, 2009 Posted July 11, 2009 My Ball mill in action I made some changes in my ball mill and now is better.i put second saft and some new pulleys http://img37.imageshack.us/img37/481/image090v.jpg
Swede Posted July 11, 2009 Posted July 11, 2009 Nice ball mill, PyroGeorge. I like the idea of tying the two shafts together in that manner. It'll definitely help prevent slippage of the jar, which can be a real problem. I really like the heavy duty stand, obviously well-made. Can I offer a suggestion? Can you insert a thin plywood shield between the rollers and the motor, to catch any potential spills? It's not a matter of IF the jars will leak, more like WHEN. Otherwise, that is a superior homemade mill.
pyrogeorge Posted July 12, 2009 Posted July 12, 2009 Thanks Swede,Yes i will put a protection between rollers and motor,i havent't finished yet.I will post new photo when i finish my ball mill.
pyrogeorge Posted July 16, 2009 Posted July 16, 2009 95RPM is very fast speed for the ball mill?i must reduce the speed or not?
FrankRizzo Posted July 16, 2009 Posted July 16, 2009 How large in diameter are your jars? 95RPM would be much to fast for anything over 4".
pyrogeorge Posted July 17, 2009 Posted July 17, 2009 7'' is the jar..i think too that is fast speed..Do you know if i can test my ball mill if grind without problem in that speed?for example if i mill a composition for 1hour and i screen it in 120mesh and all the composition passes is it good?
FrankRizzo Posted July 17, 2009 Posted July 17, 2009 (edited) 7'' is the jar..i think too that is fast speed..Do you know if i can test my ball mill if grind without problem in that speed?for example if i mill a composition for 1hour and i screen it in 120mesh and all the composition passes is it good? You can certainly try it. When loaded down with a full mill charge, the jar may rotate a bit slower which will bring you closer to maximum efficiency. For testing black powder, I've found that ramming a tube full of *exactly* 1" of powder in a 0.25" diameter tube, then recording a video with my digital camera and counting the frames, gives a pretty good indicator of efficiency. Take samples of your powder every hr. for 4hrs and see how the speed changes. A good powder should burn ~2sec/inch. Edited July 17, 2009 by FrankRizzo
pyrogeorge Posted July 18, 2009 Posted July 18, 2009 Also when i want to calculate the speed to buy the proper pulleys,how i must measure the pulley?Outside dimension or the groove?for example i want a 2" pulley..i must measure the O.D?Or 2'' must be the groove for the belt?
FrankRizzo Posted July 18, 2009 Posted July 18, 2009 George, You measure the diameter of the pulley where the belt rides (in the groove). The spec sheet that comes with the pulley often has that info too. Look for the "pitch diameter" measurement.
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