Bju90 Posted March 8 Posted March 8 Any major issues single component milling with what I assume to be mild steel? I ordered 316 SS media and milled 75/5 Kno3/Charcoal. Turns out they weren’t SS as they started corroding soon after, compared to a small qty I had if genuine SS that did not corrode.
Arthur Posted March 8 Posted March 8 Iron oxides can be a catalyst/rate modifyer in burning reactions, so yes it's possible that there could be adverse reactions if you have even single component milled mixtures. Whether it's significant in your case, only you can tell . BUT I'd suggest against using steel mill media. Proven inert mill media includes lead, and alumina ceramic balls.
dgsh009 Posted June 5 Posted June 5 hi what about chrome steel ball (used for bearings), is it suitable for BP milling? https://www.amazon.com/chrome-steel-balls/s?k=chrome+steel+balls
DavidF Posted June 5 Posted June 5 For single component milling, 304 stainless steel is perfect. It is truly inert for milling the things we mill. Very small SS media (1/4-5/16") is perfect for reducing charcoal to a very fine state for making screen-mixed BP. Using lead to mill charcoal will rapidly wear the lead media, with the missing lead all being in your charcoal. Properly hardened lead is good for milling complete BP, and will not wear much in that application. I used chromed steel bearings for milling potassium nitrate- once. I left the media in the jar of milled powder and it peeled and corroded the first time. I wouldn't use mild steel to mill anything pyro-related. Ceramic is the cheapest and least efficient. After a long time it can degrade and leave hard ceramic bits in your powder. Brass is perfect for BP milling and single component milling of most pyro chems. An often unseen risk in milling BP is the small amount of hard little rocks that can be found in greenhouse grade potassium nitrate. I screen my nitrate beforehand. I would go so far as to say that single component milled BP done with SS is on par with the performance of 3 component milled BP done with ceramic. 1
dgsh009 Posted June 5 Posted June 5 Brass ball is unobtainable and may expensive. hardend lead is too.(and maybe toxic effects for human) ceramic is lighter and expense. so chrome hardened steel ball is more available.
LiamPyro Posted June 5 Posted June 5 I can second that 5/16” brass balls work GREAT in a small HF mill… they’re a bit of an investment but won’t wear out for a looong time, and won’t contaminate everything you mill with lead! Just saying.
Mumbles Posted June 6 Posted June 6 To build on the discussion around media size, there is a give and take. The most commonly used material you'll find information about is going to be larger, 1/2" or a bit larger most of the time. Bigger media has better crushing ability. It's the same concept between rod mills used to crush large rock into smaller material for mining or construction. Smaller media however has much better grinding ability. It has more impacts per second because the same mass or bulk volume of media has substantially more individual pieces. Larger media allows you to get away with using substantially coarser ingredients like prilled nitrate and lumps of charcoal. If your material is finer, like crystalline hydroponic grade nitrate and pre-ground charcoal, you'll have better results with finer material. I personally used 00 buckshot for a long time, which is slightly over 5/16". Great results, but I did end up with the occasional bad batch of BP due to larger or harder chunks of charcoal. The charcoal was pre-ground with a meat grinder.
Carbon796 Posted June 6 Posted June 6 (edited) Years . . . ago . . . I was talking with Rich Wolter about buying some lead molds. To cast my own media. Long before I had my own machining equipment. Or anyone was casting and selling it reliably in the US. Rather than selling me tooling. He told me, he had switched to using a rod mill. And preferred it to spherical media. And advised me in the same direction. Spherical bass media may be hard to find and expensive. But brass rod is pretty common and probably far less expensive. It's also guaranteed safe for BP Type comps. ( 304SS rod may be even cheaper ) Doesn't really matter how cheap or available something is. If you're putting yourself or other's at risk. While you are waiting for THE accident to happen. Edited June 6 by Carbon796
rocketboy242 Posted June 6 Posted June 6 Please explain how a rod mill works.Are long rods used or is the rod cut into smaller pieces ? Thanks,
Arthur Posted June 7 Posted June 7 Long rods are used in rod mills. The bad failure mode is when the long rods tangle, always bad -to terminal! Usually needs all new rods.
Carbon796 Posted June 7 Posted June 7 With an over square jar, proper length rods, and a proper media fill. It's pretty much impossible to have the media tangle.
dgsh009 Posted June 7 Posted June 7 thank you all Is there a ratio (formula) between jar and media o.d for optimizing milling process ?
Uarbor Posted June 24 Posted June 24 As others have mentioned red iron oxide is a catalyst I would I would not do it myself. I personally use nothing but lead. I was originally using antimony Allied lead only but I couldn't seem to find any one day and decided to go ahead and use plain old lead works fine. I start off with 60 caliber or so so that it wears toward the spec rather than away from it.
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