Ball mill "bunkers"

[Pretty green flame]

Good evening

 

We all know ball mills are potential grenades and the damage of 600grams of BP going off in a residential area will be more than enough to raise a couple of eye-brows. In consideration with this i have decided to build something like a ball mill bunker.

 

The general idea is that the bunker should muffle the sound and contain the explosive blast by directing the fragments upward out of harms way.

 

So my idea is as follows.

 

I would place the ball mill in a fence like construction (out of plywood) with hollow insides, the hollow space would be filled with dirt. The top would be covered with a sheet of plywood on top of which i would place some light bags of dirt.

 

What do you guys think, would this be ok for the task at hand?

[DeAdFX]

Use sand bags or dirt bags. They are cheap and can be stacked to any height you wish.

[shadopyro]

I've thought about your point and to be honest im in the same problem, im in a quiet residential area and if something likea ball mill decides to throw itself a tantrum then im gonna get alotta complaints!

 

i would say that your idea is good, but what if the sides where to be just wrapped in multiple layers of that fabric they use from sandbags? then no shrapnel will get through...

[Ozzy]

I think thats a bit over kill but every time i ball mill i dont think about it but my friend has had his mill blow up 3 times.

[TheSidewinder]

Just dig a hole in the ground about 2 feet deep. Place a board in it to keep the mill flat, add some sandbags at the edge if you wish, then mill away. If it goes boom, it only goes UP. Tell the neighbors "What big bang?"

 

M

[Pretty green flame]

Sounds like a plan

[shadopyro]

Unfortunatly i dont have anywhere suitable to dig a hole in,...for some reason i'd rather have a small ballmill acciedent than get bitched my my parents for wrecking the lawn! (i've dont that once already with a half buried mortar which blew up and i got the guilt treatment! )

 

i think i'll probably just leave in the garage for now, maybe just leave one of those small thick wooden fuit crates over it or something. If anything goes off well the garage is about to be taken down anyway because its fulla asbestos!

 

Ozzy, 3 times?! what was he milling?! what was the main reason?

[Ozzy]

Unfortunatly i dont have anywhere suitable to dig a hole in,...for some reason i'd rather have a small ballmill acciedent than get bitched my my parents for wrecking the lawn! (i've dont that once already with a half buried mortar which blew up and i got the guilt treatment! )

 

i think i'll probably just leave in the garage for now, maybe just leave one of those small thick wooden fuit crates over it or something. If anything goes off well the garage is about to be taken down anyway because its fulla asbestos!

 

Ozzy, 3 times?! what was he milling?! what was the main reason?

He uses steal media XD

[hst45]

Damn, he really does have "steel balls!" But soft brains.

[brainfever]

You know, lawn is a great thing.

 

Take a shovel and cut 3 sides of a square or rectangle. Lift the bottom of the U by going under it horizontal with the shovel (leave a good portion of dirt on it, a few cm) and flap it over the rest of the lawn like you would open the cover of a bed.

Start digging in the dirt patch you just made, as deep as your ballmill needs + a bit spare. Put a piece of board in there to place your ballmill on and place some pieces of wood against 2 opposing sides. On these supports comes a final board that must be strong enough to carry the lawn, dirt and optional pet.

Close the "bed cover" and place something over it so no human will go stand there or can place a big weight on that spot. Or reïnforce the supports so it can withstand the pressure without collapsing.

 

Your ballmill is now covered, muffled and out of harms way if you chose a good place in your garden.

This will not stop all the sound of 600 grams good BP igniting in the ballmill, but it will retain most shrapnel and direct anything else generally upwards.

 

Keep the patch of grass well watered, because it will suffer much quicker in dry periods. Also try to cover the extension cord dissapearing in the lawn at some point.

[hst45]

BRaINFeVEr, you are a crazy man, I love it! Stealthy, safe, and quiet. The only problem I see is that it adds to the gardening work-load; you'll have to mow the ball-mill!!!

[brainfever]

No, actually the problems are:

 

-Cave-in of the pit. (reïnforce)

-Water in the pit. (pump?)

-It looks suspicious if you have something hidden under the lawn.

-Finding the exact same spot again if you need to ballmill something and you have a big garden.

-Popping something in and checking every 5 minutes will become a muscle strain.

[EEguy]

I have just purchased a ball mill rock tumbler and have a few safety questions. I'm new here, and figured this was a good thread to ask them, and not start a new thread.

 

I am aware that you need to use non-sparking media when milling BP, like lead or another soft metal. I am also aware about precautions needed to prevent pyrophoric aluminum when milling aluminum.

 

I am wondering about milling media for aluminum and magnesium. I think a harder media is needed, and am leaning twords chromed steel and/or hardened steel bearings. Are there any hazards that I should be aware of when milling magnesium or magnalium (50/50)?

 

Is my garage really a bad place to put it?

 

Much thanks.

[Mephistos Minion]

I suggest stainless steel based on what I have read. Chromed steel should also work. I would not personally mill MgAl indoors, or close to any building as the heat generated by a large batch ignighting would be very intense.

[deadman]

About safety bunker:

If you are looking for complete muffle and ball restraint buried with sandbags/mudbags is the best way to go on a budget.

 

Another problem for burying your ball mill:

>power source - it would be a bit conspicuous with an extension cord leading straight into your parents lawn

 

Milling media:

There isn't a definite law that only hard metal sparks and soft doesn't. Brass is hard and doesn't spark. And supposably there are Stainless Steel alloys that won't spark. I would suggest lead filled brass tubes as is mentioned often.

 

Question of my own:

Many people use the lorton rock tumblers as their first ball mills or just for another cheap one. I was wondering if it was used for milling metals that become pyrophoric and a small diameter syringe was used to pump in a small amount of air to oxidize what would ignite with too much O2 as if the jar was opened. Since it is rubber, it should be able to close itself for minimal product loss. Comments? Theories? Shoot downs?

[shadopyro]

Heh musta been pretty scary huhn?! I've tried linseed oil with Al foil before but i must've added too much as the end Al powder was clumped together.

I like the idea of using a syringe for adding small amounts of 02 to the mill jar, and i guess a hot melt glue plug can be reused to stop powder from falling outta the hole?

[EEguy]

Thanks a bunch for your advice siffup, deadman and Mephistos Minion. I plan to dig a pit out back for my mill soon.

 

Siffup, how long had you milled the Mg before you opened it to have it go pyrophoric?

 

Linseed oil seems like a pain to separate from the Mg/alloy when you're all done milling. Are there any other methods or additives you know of?

[shadopyro]

Other than covering the particles with resin, maybe you could try using the solution of potassium dichromate to try and protect the Mg. I'm not sure though, as pot. dichromates used for protecting the Mg in compositions more than milling.

PGF, Mumbles any thoughts on this?

[Bug_X]

About safety bunker:

If you are looking for complete muffle and ball restraint buried with sandbags/mudbags is the best way to go on a budget.

I´m going to build a big (0,5 - 1 kg of bp) ballmill this week. I have no space to have sandbags.

 

How thick steel sheets do I need to stop the balls in case of accident?

 

If I use armour or wood, how thick do they need to be?

 

/ Bug

[Mumbles]

Well, when using dichromate to protect Mg, it integrates itself into the oxide layer. That layer would quickly be broken off and probably wouldn't offen any resistance.

[EEguy]

I have finished my MgAl Magnalium milling project; a while back actually, and thought I would add it to this thread for anyone reading through this that may be interested.

 

Making Magnalium Powder

[scarbelly]

If you don't mind my asking, what was the source of your magnesium? And approximately how much would you estimate it costs you to do that per pound or kilo?

[EEguy]

The Mg was from an old VW Bug engine case. I also got an old Mag wheel once too. The electricity to run the saws-all and foundry is less then $5 to do several 4lb ingots. The 12lb ball mill is like leaving a 100W light-bulb on for 2-3 days, which can make about 2-3 pounds with my mill. Bigger mills are much more efficient. The Mg and Al is free if you know where to look. So all said and done, I estimate about $5/lb. If you add your time at a normal $20-30 per hour wage, it's probably not worth it. Just buy it online ~$15/lb if possible. However, this method will rid you of quantity and shipping restrictions, a necessity if you are launching lots of motors per year.

[scarbelly]

My time is practically valueless Thank you for the information!