34 replies to this topic

[Richard H]

Bernie, that is a very interesting idea. The unique shape of them would make them ideal for casting lead into. You've got me thinking now...

[Stuart]

Thats a good idea actualy. I might have to see if I can have some empty .22 cases from some people I know. They certanly dont have a shortage of them. Dont know if they would be heavy enough though. Mabye if I had about a thousand of them it would do it or if I put something heavier than lead into them...like Uranium. As for the copper pipe barrel, if you dont mill things together (like me), then your safe.

Stuart

Edited by Stuart, 12 December 2003 - 07:15 AM.

[lord_dranack]

Do you need a licence to buy empty cartridge cases (you can get them for reloading)?

Edited by lord_dranack, 12 December 2003 - 12:19 PM.

[bernie]

I think you would have a tough time pouring lead into an empty .22 cal. case. A .45 ACP might be roughly the right shape.

[tomu]

I've thought about using spent catridge cases, too. But the .22 have rims and the pistol cases like the 9 mm Luger or .45 Auto have a groove around the base. This bothered me and I bought me some brass pipe in a model shop. Cut it to pieces and filled it with lead. They work great.

About the non sparking of copper see:

=====
http://64.90.169.191...explosions.html

Published by the Copper Development Association Inc.
to highlight market development news of the copper and brass industry
Copper Alloys Tools Prevent Dangerous Explosions


OSHA Stresses Safety

The Occupational Safety and Health Administration (OSHA) requires the use of copper alloy safety tools in situations where explosions are feared. That's why copper alloy tools are in wide usage, even though they cost three times as much as their counterparts. The nonsparking requirement accounts for 90% of usage. Copper alloy tools are also corrosion resistant and nonmagnetic. The former feature is why the Ocean Spray Company uses bronze rakes (instead of steel rakes, which rust) to handle cranberries
=====

There are other sites about the non sparking quality of copper, do a google search if your interested.

I hope this settles it.

Btw I just used the copper pipe because it was easily available to me. If you want to use plastic that's fine with me.

[BigG]

I hope no objection will emerge from this rather long post.

The posts on the thread were enough to make me go back to my books and have a discussion with a few specialists on the subject.

First was a friend of my father who has a family business making metal pipes (he is last in the line. His kids think it’s not a very respectable job). He was actually delighted with my question: “so you say all of you people from a younger generation are sitting on this so called forum and discuss the quality of copper pipes?”
- “Yes…”
- “Wow, perhaps there is hope after all… And as for your question – Copper does not spark”

gee. I hate to get my facts wrong – “But I have seen it spark. I personally hammered a copper pipe on a copper pipe in pitch black – it sparked!”

“Well, not pure copper. Both hard and soft tubing are usually made form 99.9% copper – however, there are other grades, which are made of specific reasons. Grades like 90%-10%iron or 70%copper-30%titanium might very well spark, and the copper/iron one is common. Unfortunately, when you buy it from a shop – copper tube might have more then just copper. You need to ask.”

He did made the point that as far as he knows copper is not used in milling (at least he didn’t sell any for that purpose), and on this subject – I had help from the world expert of the subject of ball mills Lloyd E. Sponenburgh who kindly answer my query with the following e-mail:


“There really exists no danger of sparking from the use of copper or
brass in mill components. In fact, it's a very safe material from the
standpoint of impact or static generated sparking.

There IS a danger concerning the contamination of pyrotechnic materials
with copper compounds. Copper is a strong catalyst for many compounds
-- so much so that it can initiate spontaneous breakdown of some
oxidizers (like Ammonium perchlorate).

I've always advised against using copper or brass milling media for this
reason.

If you only always use the mill for making black powder, there should be
no problems. I would avoid using it for milling any chlorate or
perchlorate oxidizers of any kind.

Yours,

Lloyd”

Last notion to sum this subject comes from Lancaster who mention in his book that black powder was used to be made my pressing the composition hard between copper plates and the using a wood mallet to break it up to small pieces. Many accidents happened during the pressing stages and it was concluded that the copper was made voltaic and therefore generated a spark. Copper was abounded for this reason.

My apologies to Tomu as it seem like copper do not spark after all.

BigG

[bernie]

I still like the idea of a rubber drum the best. Flubber for the milling media.

Rather thoughtful of you to research that Big. Still wouldn't find me using a copper tumbler though.

Cartridge cases aren't ideal but handy if you had a mess of them and could keep the different oxidizer/bp media seperated. Then you wouldn't have to clean them. Ideally I would think that a single, solid formed media with no spaces( as exists to some degree between brass/copper tubing and the lead core) for different bits of this or that to creep here or there. Homogenious was the word I was after.

An excellent discussion. It's always good to keep a keen eye for safety.

[Terminator]

Tomu,

Don't know much about Ball Mills so can't comment too specifically on the point, but I believe you have missed one valuable safety point:

You say that if the copper pipe mill exploded it would just splay out the ends of the pipe as copper is soft.

However, what about the lead balls inside? It seems to me that any explosion in the pipe sufficient to splay the pipe, would burst these out like a crude shotgun with potentially horrific consequences for anyone within a short range.

From a safety point of view, I would have to say that one of the previous suggestions of MDPE (a soft tough plastic) with blow out tube ends sounds best. The soft nature of MDPE makes it agreeable to deformation.

(I believe that yellow Gas piping is MDPE if you need a large bore. I certainly know that the blue water piping is MDPE although this is usually only 1 inch diameter. Perhaps a friendly roadside workman would give you an off cut of the gas stuff?)

An even safer alternative to a sealed blow out cap would be to have a top cap made of fine mesh so that it vented some of the gas (pressure) rather than or before blowing out. I don't know how practical this would be for a Ball Mill though.

Remember, Black Powder is not a true explosive. It is a fast burning powder that produces a large volume of gas. It's not the powder that explodes but the vessel that contains it.

Therefore, whatever material you use for the mill, (non-sparking being obviously better!) if you provide the gas with an adequate means of escape in the event of accidental ignition, you will avoid an explosion. Just don't stand over the vent!

Al.

[Stuart]

Me and my friend have almost finnished our new ball mill. There are some interesting features about it. The gears are made from wood (we made them) and its 1.2 meters long by 0.5 meters wide. When its finnished (sometime tomorow I hope), I will take some pictures.

Stuart

[brightonben]

As we're on the subject of ball mills...

On my very unsuccessful Christmas shopping outing today, I bought a set of dumbbells for a friend. As I was walking out of the fitness shop I noticed various sized rubber bottles containing creatine and such like, perfect for your average ball mill. Admittedly they are VERY expensive bottles so try asking one of your body-builder friends if you could have their discarded ones.

[Terminator]

Just had a thought from what Tomu said.....

Has anyone thought about using solid copper ball bearings as the ball media instead of lead?

Rather than having a copper tube, you could have a plastic / rubber tube and copper ball bearings.

Being harder I would expect them to make a better job of crushing the powder and unlike lead there will be no tendancy to contaminate the tube / powder with lead dust. (The amount of copper shed by the balls will be insignificant.) Also, their hardness will eliminate any tendancy for clumping (lead balls can in some applications, (I don't know about Ball Mills), have a tendancy to attach themselves to each other and clump together).

Al.

[lord_dranack]

There IS a danger concerning the contamination of pyrotechnic materials
with copper compounds. Copper is a strong catalyst for many compounds
-- so much so that it can initiate spontaneous breakdown of some
oxidizers (like Ammonium perchlorate).

It might not be too good an idea because of this risk

[Terminator]

Interesting, I didn't know that. Presumably therefore this is another reason not to use a copper tube as a Ball Mill container.

But, what about brass bearings then could these be used instead of lead?

PS should beware "brassed" bearings as I'm sure most of you are aware that these are just coated steel (risk of coating wearing and then sparking).

Al.

[BigG]

Lloyds pointed out that this also reflect a problem with Brass, and this caught me by surprise as well - As I always thought brass to be a superior balling material to lead. The usage of lead or more recently, none sparking ceramics - is preferable. Mind you, this reflect a personal opinion only - and he did mention in a recent communication that his knowledge comes from researching the existing field rather then having the full chemistry knowledge - but I still consider his one of the experts in the area.

[tomu]

Using heavy metals or alloys like copper or brass with an ammonium nitrate or perchlorate is dangerous because there is the possiblity of the forming of azides.

But milling the usual components with them like Potassium nitrate, -chlorate (alone), -perchlorate (alone) or black powder there is no problem. The possible metal contamination is no practical problem in my opinion. I'm using hardned lead balls and now lead filled brass pipes (small pieces of pipe) for quite some time and have not expierenced any difficulties with metal abbrassion or contamination, neither in the media nor in the milled compounds.

Professional ball mills are often lined with hard ceramics and some use ceramic milling media and they don't come cheap. This mills are designed for high effeciency, which doesn't matter much if you use a ball mill just for a pasttime pleasure but is important in industry where stuff get's milled by the ton.

Could that be that there is a lot of theorizing going on in this discussion?