FiroweWorks Posted October 29 Posted October 29 Hello, everyone. Does anyone have experience with inexpensive pre-made ball mills such as this one https://www.pyrocreations.com/ball-mill-6-lb-capacity.html?search=ball mill&description=true. Are they worth the investment? Do they last long? Thanks.
Arthur Posted October 30 Posted October 30 Light weight hobby rock tumblers are usually poor at tumbling heavy drums so don't use lead media. However they usually work fine with ceramic (Alumina) balls.
Mumbles Posted October 30 Posted October 30 As a quick answer, they work, just not as efficiently as something designed for BP. They are what a lot of people getting into the hobby with start with, but typically are not geared for optimally making black powder. They'll eventually work, but will just take longer. They spin at 30-45RPM, where optimal for that size of jar is close to 90RPM. I would average about 8-12hr of milling to make good BP, that in an optimal mill would only take 3-4hr. The motors are underpowered for heavy loads, like using lead media. If using lead, you may also need to upgrade the belt on the pulley to handle the increased load and potentially give it a kick start to get it spinning. If you can find the right size, replacement vacuum cleaner belts make pretty durable replacement belts. It's a worthwhile $3 upgrade. It can take some extra manipulation, but for a while people were adding additional layers of hose over the drive roller to increase the RPM of the unit and make them more efficient by increasing the RPM of the jar. Also, these types of item are often available from industrial tool suppliers at a cheaper price. https://www.harborfreight.com/6-lb-dual-drum-rotary-rock-tumbler-59474.html
Arthur Posted October 30 Posted October 30 Cheap rock tumblers run slow by ball mill standards so take longer times to mill ingredients to powder. Typically a rock tumbler takes 12 to 24 hours to do whar an optimised ball mill could do in 3 - 6 hours. Buy the cheap mill as Mumbles suggests and do tests around 12 hours or more, OR build an optimised mill yourself and run it for 3 - 6 hours. Remember powder is flamable so design your own (if you do) with this in mind -at least put the mains switch well away from the mill 30ft+ being a good start.
Carbon796 Posted October 30 Posted October 30 Maybe it's just a difference in size. But, a optimized mill with a rubber lined 6qt hex drum. Is 2hrs and done.
FiroweWorks Posted October 30 Author Posted October 30 Mumbles: In the Ball milling FAQ thread, you said that stainless steel media can be used in combustible compositions such as black powder. But, ive seen different sources that say otherwise, is your opinion still the same or has it changed?
cmjlab Posted October 31 Posted October 31 (edited) BLUF: The safest* method for milling 3 component B.P. is to use lead media, or non-sparking ceramic media (I've no experience with ceramic). You shouldn't be milling other chemicals together, unless you know they aren't combustible together, like milling K-Dichromate into KCL04. *Safest means there are still risks because you are grinding by friction and impact, a very combustible material and should take all precautions in case an incident does occur. --‐--- Long Answer: Stainless steel grades 304 and 316 are the grades generally used if someone wants to use stainless media. They are very expensive now a days. Lead and non sparking ceramic media are the only ones most people would 'recommend' you use for milling a complete comp - a complete comp meaning b.p. or similar comps containing KNO3, Charcoal, Sulfur (like Chrysanthemum, Spider Stars, Tiger Tail, etc) Then there are people like myself who do use 304 stainless media for b.p. I would never recommend someone do it - it comes with more risks than lead media does, and I have the space to safely do it, and I mitigate risk as much as possible by operating under the assumption it WILL explode one of these times (remote start / stop, barriers to direct an explosion up, nobody around but me, no other properties or structures near by, careful handling when emptying mill jar and separating media, etc.) (**Note: The only complete comps you should be milling are black powder or 3 component star comps containing B.P. chems. // Everything else must be milled individually. // There are a couple exceptions I know of but I don't believe your dealing in those comps yet) Edited October 31 by cmjlab Added a shorter "BLUF" 1
Mumbles Posted October 31 Posted October 31 My answer on stainless hasn't really changed. Using a non-sparking media is of utmost importance. If you use a non-sparking grade of stainless, it should be fine. Nothing is without risk of course, but mitigating it to the best of our abilities is what we need to strive for at every choice. CMJ has a great perspective. Avoid an issue as much as possible, but also have contingencies to minimize harm if something were to happen. I personally feel most comfortable with lead or brass. I've never really heard of accidents with them, where as there are a few incidents floating around from ceramic and stainless steel. Many of those can probably be attributed to using the wrong grade, but it's always sticks in the back of my mind.
Arthur Posted October 31 Posted October 31 My opinion of steel balls inc stainless is that in the presence of an oxidiser (Nitrates, (per)chlorates etc) assorted Ferrous and ferric oxides will be formed any of which will be reaction rate changing in the expected burning reactions. Simply, balls with iron can make the powder burn faster than expected, which may lead to unexpected and unwanted events. youtube.com/watch?v=h1b2w4GxBU0 at about 20 minutes in , shows a Spanish(?) factory making BP in wooden "barrels" with wooden balls! Lead balls leave lead in the powder, steel balls leaves rust, Ceramic balls and wooden balls leave less behind. Glass balls (Marbles) leave shards of glass behind which also sensitise the powder as someone on this forum found out to his extreme cost.
Carbon796 Posted October 31 Posted October 31 Not exactly Pyro related, but . . . https://bssa.org.uk/bssa_articles/sparking-risks-in-explosive-gas-atmospheres/ Often with Pyro related materials. They're usually 2nd/3rd hand/scrap materials. And you can't really be sure of, what you've been supplied with. Unless you bought them directly from the mill, with certificates. I used to run a mill with stainless media. But, it was only for processing chems, for color formula. Never BP.
FiroweWorks Posted October 31 Author Posted October 31 Ok, from what I understand, the correct grade stainless steel can be used for milling live mixtures such as BP but still have an inherent risk when using, more so than lead or brass. I wish brass wasn't so dang expensive, because it seems perfect: doesn't spark and leaves little residue behind. I would like to look at non-sparking ceramic, does anybody have a link?
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