ball mill media

[memo]

got into a discusion with this fellow about glass balls , marbles used in ball mills. i told him not to do it because it could spark. he wanted proof and the only thing i could say was pretty bad, thats what i have been told from the guys on the forum.. do marbles spark ? if they do how do I prove it. imwtk

 

memo

[DavidF]

I don't think it's too important to know whether or not they spark, as whether or not they can cause an explosion. And Burrito Bandito can tell you they can! So don't use 'em!

[memo]

that was my point, this guy wants proof

 

memo

[memo]

the fellow is on youtube he is called troll face the man. he did a diy video on makeing dark al and states in his video that marbles dont spark. i said ya they do, he wants some kind of proof.

 

memo

Edited August 29, 2016 by memo

[DavidF]

Maybe they don't And maybe, for his application they are just fine. Even if he got glass chips in his dark Al, it's not like he will be grinding it with anything else. Besides, folks mix titanium with their dark Al all the time. Maybe Troll Face really is the man!

[OldMarine]

Let him blow himself to smithereens. Anyone with that much hubris can't be a fun guy to hang with.

 

"Here in this most solemn place,

Lies the grave of the infamous Troll Face.

He blew off his ass

By milling with glass

On the bright side, he takes up less space"

[Fulmen]

It's hard to prove that glass sparks, except finding a reference to it's piezoelectric properties. But that's only part of the problem. Glass is brittle and will flake off, and ground glass is a well-known friction-increasing additive. And either way it's too hard, increasing the risk of impact ignition.

[memo]

old marine I posted your poem to his channel, we will see

 

memo

[NeighborJ]

I've seen a lot of his videos and there are tons of things he does which would be considered unsafe. That doesn't change the fact that I still like watching his videos. The glass flakes certainly do increase sensitivity but marbles do have other additives in them and they are usually metal carbonates, so in theory they could have areas of conductivity spread thru out. Any thing conductive can transfer electrons such as static charge and any rotating conductive material has potential to even generate electricity. This could become even more likely to happen when you take in to account that all this is happening within the electromagnetic field of the ball mill motor. This is all extremely unlikely to cause a spark but it is entirely possible to get a stray iron filing in the comp with these rotating conductive metals which will create it's own magnetic field and then you've got a problem.

[memo]

I too watch his videos, I subscribed to his channel couple of years ago. some stuff is pretty good, others so so. he feels he is 100 % right marbles will never cause a problem. take a look at his response to me.

 

memo

[otto]

It's hard to prove that glass sparks, except finding a reference to it's piezoelectric properties. But that's only part of the problem. Glass is brittle and will flake off, and ground glass is a well-known friction-increasing additive. And either way it's too hard, increasing the risk of impact ignition.

 

Not tryin' to pick a fight. I'm just a curious guy (besides, I bought into a big pile of zirconia media). If "hardness" is a problem why is zirconia media generally considered safe? Or am I mistaken? I'm pretty sure zirc is much harder than glass.

 

Again, I'm trying to stay on the safe side here and looking for some input. You may be onto something with the micro glass flakes sensitizing the comp being milled....

[OldMarine]

I'll put it out just as I received it.

As long as you feel fine with only a tiny bit of rat shit and scrap iron in your cereal, eat up!

[OldMarine]

Even if the milling process didn't go wrong using glass media, picture ramming a simple rocket with the glass shard ridden powder.....bam! Shitty guidance cost you your left hand!

Tell that charlatan to kiss my pyro ass. I have credentialed pyros who'll ruin him in a second in an open forum.

[NeighborJ]

The marble milling media is more than questionable and the fact he is guiding others to use it is more of a problem. If you watch his videos he is lighting piles of highly flammable substances on the 2nd floor balcony with a blowtorch. If he is lucky he may be able to learn a lesson with a long stay in the ICU and we can all see the devastating consequences on the next video. If not we may never see the video because there will be no-one to post it. If he wants to be wreckless that is his choice but it is not a good thing for him to be looked up to by uninformed individuals.

[Fulmen]

I don't think anything harder than brass or bronze is considered safe.

[DavidF]

Geez, I dunno guys. I think there's less here than meets the eye. You folks are talking about 'milling'. Milling what, exactly? The Youtube guy (that never told anybody here to do anything) is milling aluminum with a bit of charcoal- period. He also addresses the dangers of doing it. Does anybody here think that milling the aluminum foil with glass marbles is going to cause an explosion?

 

It seems like maybe everybody is unconsciously adding 'black powder' to the words 'milling with glass marbles'. The Youtuber isn't milling black powder, nor is he going to use his aluminum in anything that gets milled again. So, I don't see how potentially having glass chips in the dark aluminum is any worse than mixing the milled aluminum with sponge titanium, as is often done.

 

I'm not trying to be the guy with the unpopular opinion- but, I have been working on single-component milling to avoid the potential danger of milling black powder. And yes, my media is hard stainless steel. I mill the potassium nitrate with it too. And parlon. And perc, and....

 

Now, on the subject of milling black powder, one important safety tip I think everybody should share is to screen out your charcoal and your potassium nitrate before you use it. Charcoal can contain nails, staples, etc... My greenhouse grade potassium nitrate has had pieces of stone in every batch I've screened. And it's not just limestone either. It's also hard stone, like chert or something. Now that's dangerous!

 

I understand that marbles have already caused an accident- with black powder- unless the nitrate had rocks in it like mine did. Then it might have been the rocks that did it. I also understand that if we say marbles are OK for aluminum, some joker might think They're OK for BP too. My personal objection to 'piling on' the Youtube guy is because I have been that guy. I have had one of my practices deemed unsafe because someone could take my procedure, change it from being relatively safe into something far more dangerous, and get hurt. And because of the fear of this unknown (possibly non-existent) person bastardizing my procedure and maybe having an accident, my procedure was demonized. And so I stick up for TrollFace Please don't hate on me fellas. Discussing this stuff is important. My .02.

[NeighborJ]

OK David I just have one point to make and I want to say it right.

You are correct, the aluminum can be safely milled with marbles. However the most logical assumption here is that it will eventually be added to a pyrotechnic composition and only screen mixed. When I was a kid I'd play in this old junkyard, it had cars and other stuff which had been there so long it had trees growing thru them. We found joy in destroying the car windows and let me tell you those windows are strong we'd throw bricks at them only to have them bounce off, tough stuff. We were amazed to find that if a tiny piece of porcelain, no bigger than a dime would shatter any window which it was thrown at. The reason for this is hardness and surface area. The porcelain chip was very low in mass but hard and pointy, with this hard pointy edge it was able to exert a tremendous ammount of energy on a very tiny spot. My fear for milling with glass is that even though any glass chips should be very small it still has the potential to exert a lot of force on an unsuspecting grain of chlorate, perchlorate, ap or whatever oxidizer it may be mixed with. This is my opinion and I've backed it up with all the logic i have. So imo marbles should never be used as media unless the aluminum will never be used in pyrotechnics.

[DavidF]

Haha, I had the same junkyard experience! I think it's worth noting though, that the glass was tempered. So, it has a core of glass with a 'skin' of outer glass tightly shrunk on to it. The inner part of the tempered glass is under constant stress. Violating any part of the skin causes the whole thing to explode into bits.

 

I agree that marbles are not an ideal choice for milling. I agree that anything milled with glass could have glass chips in it. I have never used marbles, and I never would.

 

But: I don't see that Troll Face's actions (in the dark Al video) are dangerous in and of themselves- other than the dangers he specifically and thoroughly warned us about. People do regularly binary mix dark Al with oxidizer, and add titanium sponge to it. With commercial salutes, that abrasive mixture is then blasted out of a cannon! Titanium is much harder than glass. So is the porcelain you used to break the tempered glass. But still- having a few glass chips in your VitF is not going to have the ability to apply dangerous forces to it, as could happen in a mill jar. The chips would be freely floating in the mix. This is my opinion only, and I claim no special knowledge.

 

I just think it's a little unreasonable to publicly criticize somebody in a completely different forum than where they post, without them having any knowledge of it, or the ability to respond to the criticism. So I played devil's advocate on his behalf.

 

I think we all have our own ways of perceiving things when it comes to safety. I think we can agree that when it comes to safety, erring on the side of caution is the best course of action. To that end, I would never even make my own dark Al, much less with marbles! But the video was interesting

[NeighborJ]

Haha most of my work is in the gas and oil field which as you can imagine gets watched over by an army of safety personnel at all times and rightfully so. It is everyone's responsibility to look out for anything which could possibly put someone in danger. I'd rather be hated for scolding someone then be a loved one at their funeral. I have the personal motivation of having been burned in a kerosene fire and spending three weeks in the ICU burn unit at age 20. I know what can happen and have experienced it, I can only wish there was someone I could hate for being a safety dick on that occasion. I hate telling people they are screwing up but I just won't back down when it comes to safety. Anger and resentments are far less painful then what I have experienced.

I guess my point is, we have accepted and relatively inexpensive methods and media for such a purpose. Why even consider using glass when the consequences of that one in a million accident are so high. At some point you will need to ask yourself IS IT WORTH IT?

Edited August 29, 2016 by NeighborJ