34 replies to this topic

[Prodigy]

I've decided that I'm going to make my own ball mill as 5 minutes in the old mortar and pestle just doesn't cut it.

The only thing I'm concerned about is what to use for the jar. I was thinking that a coke bottle might be enough?

The only problem I thought about was that it might create static?

I presume it won't wear down with just lead balls in it.

Oh and I'm sorry if this has been discussed before but I searched for it and couldn't find anything.

[Richard H]

A coke bottle sounds way too flimsy for a milling jar, it certainly won't last very long full of lead. Make a jar with say 5-6" diameter PVC sewer pipe and cut some wooden bungs for each end. If you can get HDPE instead of PVC that would be even better from a safety point of view.

[Stuart]

I use a old nuts jar. Big and strong and putting the ribs in was easy. The one you see in my Avatar uses a old Sodium Chlorate container.

Stuart

Edited by Stuart, 06 December 2003 - 08:30 AM.

[BigG]

I've decided that I'm going to make my own ball mill as 5 minutes in the old mortar and pestle just doesn't cut it.

The only thing I'm concerned about is what to use for the jar.  I was thinking that a coke bottle might be enough?

The only problem I thought about was that it might create static?

I presume it won't wear down with just lead balls in it.

Oh and I'm sorry if this has been discussed before but I searched for it and couldn't find anything.

Won't wear down? It won't survive more then 10 minutes mate you need something much stronger.

[tomu]

I made my milling jar out of a piece of rain pipe made of copper. The end plugs are a cut out of plywood and epoxied in.

The e-motor with reduction gear (about 90 rpm) is from ebay costs were about 10 Euro.

[BigG]

Then you are simply risking your life. Copper is not brass – many grades of it spark and lead may spark when smashed against it. It also produces the most dangerous shrapnel. Use thick polyethylene or HPDE pipe. PVC is also much better for a mill jar.

[pyrotechnist]

Ho dam you are risking life and limb using a copper pipe since copper is a good heat conductor and with lots of lead smashing around in there it will generate heat more quickly than plastic. I am going to use my jell jar its made from plastic do not no what type of plastic thou. And does anyone no if this is good to use? I can?t make my mined up after reading these posts it made me think more of what to use for my ball mill.

[tomu]

I'm using copper for quite some time. Copper, brass or lead doesn't spark when smashed against it, no way. Tools for explosive enviroments (e.g. oil or gas installations) are made of copper because it doesn't spark. You can smash copper, brass or lead as heavy and long as you want you want get sparks.

Yes copper is a good heat conductor. So what? The heat generated by the milling action get's dissipated quickly by the large area of the copper pipe.

Shrapnell: Have you ever seen a metal pipe destroyed by an black powder explosion? I guess not. Copper especially is a soft and tough metall, if it blows up it will look more like a peeled banana, there would be very little shrapnell. Anyway, I wouldn't want to stand near it.

Even the old type handgrenades with a cast iron body ( pineapple and mills charge type) and a high explosive filler had serious problems with breaking up in many shrapnells. Their shrapnell distribution was poor, this is why they were replaced with modern prenotched types.

Why copper would make the 'most dangerous shrapnell' escapes me.

Edited by tomu, 11 December 2003 - 07:04 PM.

[BigG]

Tomu ? I?m not here to criticise ? but to voice an opinion on potential safety issue. You can do whatever you feel like. However, I have to disagree with you. I?ve seen copper spark. It soft and the part that blows off will create many fine shrapnel pieces ? and the fact that nothing happened yet in your case does not mean it?s safe. Have a look at all pyro tools site and show me one that uses copper. Gas and oil are not explosives, but highly flammable. I don?t claim to know what gas installation use ? but I assume there are other considerations when it comes to pipes in those installations.

As it stands ? and I have no problems to stand corrected ? I have NEVER seen a mill jar made out of copper. Also, nobody uses copper for milling media. I also believe it has to do something with chemical reaction between copper and other chemicals ? but I?ll be happy to dig more into the issue.

[Richard H]

Although to be fair BigG, Kyle of passfire.com does present a rather concise article on manufacture of copper pipe lined lead cast media.

The ideal material in my opinion for a 'safe' milling jar would be HDPE with end plugs designed to readily give way in the unlikely event of an explosion, which at worst would merely 'bell out' instead of fracturing the jar.

[bernie]

Wouldn't a rubber drum be great! Bet that copper tumbler makes a heck of a lot of noise.

I'm gonna have to side with Big on this one. Copper just seems odd if nothing else. It's also a very soft metal and I would expect it to wear poorly.

Not very scientific sounding but....would you rather get bonked over the head with a plastic pipe or a copper one.

The lesser of the two evils is most certainly the hdpe. If copper was really all that great they would use it to shoot shells out of.

Another way to look at the thing is to use a somewhat weak walled plastic mill jar and if it ever does go the confinement aspect is a good thing in this case. When the jar starts to look worn just throw it out and replace it with a fresh one.

Tomu, be safe.

A very interesting discussion.

Edited by bernie, 11 December 2003 - 11:09 PM.

[Matt]

Richard, I think you mean brass pipe. I think thats where a lot of people get confused on the subject, a lot of people mix up brass and copper.

-Matt

[bernie]

Kyle does mention brass. Brass is just an alloy of copper though. Zinc is used to harden the copper if memory serves.

[Richard H]

I stand corrected

[bernie]

I wonder why you couldn't use brass cartridge cases. You would have to use virgin brass or spent cases with the old primers knocked out.