Safety regarding Hand Pulverisation of BP

[stix]

Hey guys, after reading about other peoples accidents I'm becoming a bit paranoid about my methods of making bp.

 

I only ever make small amounts of bp - 20 grams is the most I have ever made at any one time (for experimental purposes).

 

Using a ball mill is obviously impractical with such a small amount, so I use a small plastic container (Pavlova Magic) http://1.bp.blogspot.com/-kM3o5hLrOtA/UH84tQbsDXI/AAAAAAAAACw/XwFtlpHqZ8Y/s200/ImageHandler.jpg

 

The container can fit into my hand and is approx 1/3 filled with 1/2 inch ceramic alumina balls. It fits into and is held by my outstretched hand, and shaken like perhaps one would with maracas . . . (Peter Allen's "I go to Rio") . . . depending on my mood.

 

Humour aside, this is more of a pulverising action and quite violent, as the balls are thrashed against each other repetitively. I find that this makes excellent bp in a short amount of time.

 

I've recently read that these ceramic alumina balls can spark!!!. Although I'm making only 15-20 grams, I'm very concerned that if it did spark!... in my hand!!!???

 

I face away as I'm doing it - but 20gms of bp going off in your hand is probably not good.

 

Thoughts appreciated.

 

Cheers, Steve.

[Bobosan]

Hi Steve,

 

It would be best to find or make some roller mechanism to place the container on to mill it. Not safe to do this by hand, even in small amounts.

[schroedinger]

Better get a small rocktumbler, modify it and make 100g of comp with that then using your method 5 times.

[stix]

I'm pretty whacked right now - respond tomorrow.

Edited November 12, 2014 by stix

[Arthur]

Best done on a rock tumbler with a small drum.

[dagabu]

+2 on the small rock tumbler. Never in the hand...

[otto]

I don't have a ton of experience like most of these guys but I do know that when things go sideways it's not happy. That said anything you can do to isolate yourself from those mechanical processes enhances the probability that this stays on the fun side.

[BurritoBandito]

Rocktumbler++. Never shake a loaded mill jar.

[stix]

Thanks everyone for your responses.

 

Yeah, I guess I already knew the answer to my question.

 

I did always intend to make a small ball mill but got impatient and wanted to test my charcoal etc.

I figured that making small amounts and ceramic balls would be safe but nothing ever is 100% safe when making bp or any other pyro formulas, so best to be cautious and not introduce a weak link in the chain.

 

I feel a bit embarrassed by my own carelessness and stupidity, but better that, than be posting on here about how I lost a couple of fingers in an accident that could easily be avoided.

 

I've got a 20 gram mix on the go but will not be touching it until I have made a small ball mill. I already have some bits and pieces together for the purpose, so that will be my next step before doing anything else.

 

Cheers, Steve.

[BurritoBandito]

...I feel a bit embarrassed by my own carelessness and stupidity, but better that, than be posting on here about how I lost a couple of fingers in an accident that could easily be avoided...

Don't be embarrassed. Asking questions is what the forum is for. If I had the same foresight that you're demonstrating by making this post, I'd still have all of my digits. Harbor Frieght has a 6 lb. rock tumbler that is only around 50-60 bucks, or at least that's what it coated whenni bought mine. After getting your mill up and running not only will you be improving your safety standards, but I bet you'll be getting much better BP. I can't imagine shaking a jar for 8+ hours.

[stix]

Ok, Ball Mill Made:

 

 

Slightly faster than the optimum 65% of critical speed (68%).

Half filled with 20mm ceramic balls.

 

First test I milled 100gm of my standard 'table sugar sized granules' KNO3 to flour-like powder in approx. 4hrs.

I was thinking about using a larger diam. jar but this is good enough as is for my purposes.

 

Cheers.

Edited November 29, 2014 by stix

[Col]

Sounds like the balls are being thrown a lot rather than cascading, it`d be worth trying to find (or make) a larger pulley for the shaft if you can.

[stix]

Yeah thanks Col, you're right. Unfortunately I don't have access to the lathe that I thought I could make the pulleys with.

 

Smallish 8mm bore pulleys are hard to come by and expensive to order, so I had to improvise. I used some 'awning pulleys' from the hardware store and re-drilled the holes to suit. Not really what I would have liked, but it works.

 

To me it's more about resourcefulness and re-purposing discarded parts than about saving money, although of course saving money is always good . The rubber coated rollers were from an old laser printer and the motor I picked a while back for $20AU and the bearings are cheap.

 

So, what are your issues regarding the balls being 'thrown around' rather than an optimal cascade - Safety? Efficiency?

 

I could always pickup some 10mm steel bearing balls and use them JUST FOR MILLING KNO3. Fill to approx. one third - I think that would make the milling more efficient - what do you think?

 

Cheers.

Edited November 30, 2014 by stix

[Col]

You could increase the diameter of the jar using a bit of plastic pipe, expanding foam or full length internal timber battons (fitted lengthwise) to create the clearance. When the media is in the air it isnt doing any milling, safety could be an issue. Steel will likely rust, you could use stainless but i`d go for alumina if you can for safety. I`m all for repurposing stuff destined for landfill, i have two mills that began life as something completely different

Edited November 30, 2014 by Col

[stix]

You could increase the diameter of the jar using a bit of plastic pipe, expanding foam or full length internal timber battons (fitted lengthwise) to create the clearance. When the media is in the air it isnt doing any milling, safety could be an issue. Steel will likely rust, you could use stainless but i`d go for alumina if you can for safety. I`m all for repurposing stuff destined for landfill, i have two mills that began life as something completely different

 

I have some 2mm thick rubber blanket that I could wrap around the container - good for grip and I could do away with the elastic bands.

 

As far as I'm aware, the media I purchased some time back was 'Alumina Ceramic' not sure how to confirm this though.

 

"When the media is in the air it isnt doing any milling" yeah true, but you could also look at it this way - When the media is in the air, it's able to fall from a greater height and therefore produce a more impact action and 'crush' as well as grind - "swings and roundabouts?" ie.

 

a situation in which different actions or options result in no eventual gain or loss.

 

Edited November 30, 2014 by stix

[MrB]

Airborn media isn't supposed to be happening. It increases the impact force which might set bad things in motion, and means you only get the impact moment as "grinding / crushing" moment. Proper media motion means it will tumble over other media and in every collision you have some grinding action. However, with the added weight of the stuff to be milled the drum slows down some more, you might be in the right range already. There is nothing but trial and error left, i guess.

B!

[stix]

Thanks MrB,

 

The motor I have is very high torque, so not much slow down at all that I can measure..

 

According to my math, the desired rpm (given 65% of critical speed) is 109rpm. The 'worked out math' rpm and the 'actual' rpm is 114 (confirmed by video analysis).

 

I don't have an issue with the concept of some balls crashing down, I'll stick to my "swings and roundabouts" theory. Of course, if I thought there was a safety concern, I would look at other media options.

 

Being employed in the printing industry I have managed to procure some old Linotype Metal (and a lot more if needed). I COULD muck about for the next 2 months or so making moulds, casting etc... etc... A tangent I'd rather not explore as it distracts from my 'goals' but doable if I am convinced that my ball-mill could be un-safe.

 

Cheers.

[Col]

Consider a ball rolling down a hill with a 45 degree angle versus the ball being thrown from the top to the bottom. The rolling ball will do considerably more grinding regardless of how hard the other one lands

You can usually tell whats happening in the jar by the sound it makes, ideally you want to be hearing a constant rumble.

Edited November 30, 2014 by Col

[stix]

Consider a ball rolling down a hill with a 45 degree angle versus the ball being thrown from the top to the bottom. The rolling ball will do considerably more grinding regardless of how hard the other one lands . . .

 

I do value your opinion Col, but I don't agree.

 

Consider throwing a ball from the top onto a large heap - the added momentum would pulverise and crush a large amount in an instant. More than just a gentle roll?

[Col]

lol, thats ok. The composition will act as a shock absorber, so it wont be felt much below the surface of the heap. If you have more cascading and less impact you`ll notice the KNO3 becomes flour in well under 4 hours

Edited November 30, 2014 by Col

[stix]

Yeah, well tell that to the dinosaurs. - tee hee hee.

 

Anyway, I'm lazing back here in Oz on a 35C degrees day throwing back a few beers or two...

 

I'm happy with my ball mill - Apart from "ball dynamics" If there are "unsafe" issues with it, I'm all ears.

Edited November 30, 2014 by stix

[MrB]

Consider throwing a ball from the top onto a large heap - the added momentum would pulverise and crush a large amount in an instant. More than just a gentle roll?

Caught between a rock and a hard-place, it ain't. Only what cant get out of the way will actually get "milled" so the amount might not be that different. It's your call really. I'd try and get it to slow down if it turns out to rotate to fast with a full charge in the barrel.

 

Being employed in the printing industry I have managed to procure some old Linotype Metal (and a lot more if needed). I COULD muck about for the next 2 months or so making moulds, casting etc... etc... A tangent I'd rather not explore as it distracts from my 'goals' but doable if I am convinced that my ball-mill could be un-safe.

I'm SO compelled to ask you to procure, and sell (cheaply) so that i could make more good hardened media. I got a few kilos of lead left, (10-15) but it's all stick-on wheel weights, meaning it's pretty darn close to pure lead. To soft for my liking. A couple of kilos of lino-type should sort that out. But that stuff is either stupid rare around here, or i just don't know what to search for...

Anyway. Don't mess with making your own molds. Just buy a "fishing sinker" type mold from eBay. It takes a small mod on both ends to close the ports on the sides, but after that it produces workable media. If one can spend the time to, tweaking the fill ports made it a lot easier to use, but preheating the mold, and keeping it hot once started, works good enough. Just make sure to always fill it in one pour, or the layer between the pours seems to form a "weak point".

 

I'm happy with my ball mill - Apart from "ball dynamics" If there are "unsafe" issues with it, I'm all ears.

Ball milling is never "safe", if you mill live compositions, or metals. If your ceramic media is none sparking, then your as close as you can be while using ceramic media. Lead is supposedly slightly better, but makes your pristine white KNO3 gray. There is always something to improve. Perhaps the lead weight would slow the barrel down just enough, if you switch media?

B!

[stix]

Caught between a rock and a hard-place, it ain't. Only what cant get out of the way will actually get "milled" so the amount might not be that different. It's your call really. I'd try and get it to slow down if it turns out to rotate to fast with a full charge in the barrel.

 

I'm SO compelled to ask you to procure, and sell (cheaply) so that i could make more good hardened media. I got a few kilos of lead left, (10-15) but it's all stick-on wheel weights, meaning it's pretty darn close to pure lead. To soft for my liking. A couple of kilos of lino-type should sort that out. But that stuff is either stupid rare around here, or i just don't know what to search for...

Anyway. Don't mess with making your own molds. Just buy a "fishing sinker" type mold from eBay. It takes a small mod on both ends to close the ports on the sides, but after that it produces workable media. If one can spend the time to, tweaking the fill ports made it a lot easier to use, but preheating the mold, and keeping it hot once started, works good enough. Just make sure to always fill it in one pour, or the layer between the pours seems to form a "weak point".

 

Ball milling is never "safe", if you mill live compositions, or metals. If your ceramic media is none sparking, then your as close as you can be while using ceramic media. Lead is supposedly slightly better, but makes your pristine white KNO3 gray. There is always something to improve. Perhaps the lead weight would slow the barrel down just enough, if you switch media?

B!

 

Yeah, it would be ideal if it rotated slower but at this point I'll probably leave it as is. This pyro hobby has so many varied and interesting facets that you can easily find yourself obsessed over some aspect that doesn't necessarily give tangible benefits, but nonetheless the journey is always rewarding. I should be getting back into investigating hand rolling tubes with home made casein glue etc...

 

In regards to the Linotype. If only I knew!... When I was an apprentice in the printing industry some 35+ years back, one of my tasks was to fire up our 100litre or so furnace, re-melt the used linotype lead and pour various shaped ingots for our machines. Every so often we would add a small bar of - I think it was tin and antimony? to ensure the hardness remained consistent.

 

I've only got a 3 kilo bar, but definitely enough for my mill if I went down that path. Even so, I'm going to see if I can relieve my workplace of more of this potential health hazard - In all honesty, if I pointed out that there was lead lying around, the workplace health & safety inspectors would be right onto it and demand its removal asap!.

 

The ingots are only used as 'paper weights' lol. They use them to weigh down a stack of printed paper to glue the edge for pads etc. Yeah, good weights they are but perhaps I could cast some concrete ones, paint them grey and swap them

 

If I can get my hands on some more, I would have no problem parting with most of it for the benefit of fellow pyro's - a much much much worthier and useful cause than a dead weight. Obviously the shipping would be an issue - for health and weight reasons.

 

Every printing company that I've ever worked at still has some from the old days and tends to hang onto it like 'grim death', Seems a bit pointless really considering what it's used for. Maybe it's just sentimentality. You could always try a few printing places - the more established ones and perhaps mention the potential health risks, and offer a more 'green' alternative?

 

Cheers.

Edited December 1, 2014 by stix

[MrB]

There are no "old" printing mills around here. Last one burned down to the ground 5 years ago. Everything still standing has been digital since the start. Shipping, shouldn't be "hazardous" as long as it's in solid chunks like ingots. Dust, isn't goof for ya, but still not to the point where it actually is a health issue. But shipping solid stuff should be as easy as wrapping it in paper / cardboard, and sticking a name on it.

 

Not that i'm sure if anyone but me actually is crazy enough to want some. Shipping could get expensive, i'm sure. Finding out how expensive might be the best place to start if your going to look in to that. Or you might end up having a bunch of stuff, that nobody wants. (can afford)

B!

[stix]

. . . Not that i'm sure if anyone but me actually is crazy enough to want some. Shipping could get expensive, i'm sure. Finding out how expensive might be the best place to start if your going to look in to that. Or you might end up having a bunch of stuff, that nobody wants. (can afford)

B!

 

Reminds me of a short story by Roald Dahl.

http://en.wikipedia.org/wiki/Parson%27s_Pleasure_%28short_story%29

 

Perhaps I'm Cyril Boggis? Who knows, but don't read too much into it.

 

btw. Although my previous post may have been a bit "ambiguous with a touch of humour", I didn't actually 'nick' the ingot I have. I asked, and received. Unfortunately that particular manager is no longer with the company.

 

If I can get some more, say around 3 kilos - and you are actually 'crazy enough' to sort out the shipping arrangements and cost - you can have it gratis.

 

Cheers.