What's the deal on lead media?

[Swede]

As a noob, I am gathering up all sorts of stuff, and one of them is media for a ball mill. I made my first ball-milled small batch of BP using brass disks, and the results were excellent...

 

http://www.5bears.com/firew/bp020.jpg

 

But I also bought 1,000 .50 caliber lead balls. I was planning on using them, but I've read several experienced pyros here say the toxicity isn't worth it. I know brass isn't cheap, but lead isn't either, and I probably could have bought enough brass with the $$ I spent on the lead, to do the job.

 

Thoughts on lead media in general? Am I playing with figurative fire? I KNOW I'm playing with LITERAL fire!!

[justanotherpyro]

It is all relevant. In general lead is cheaper than brass as well as easier to obtain. I cast all of my media and lead @ 30cents a pound plus a very low melting point makes it very convenient. Lead media is non-sparking like other metals could be. Your brass could be alloyed with other various metals that could spark, even though its a long shot whereas lead is often alloyed with antimony which is nonsparking as well and acts as a hardener. Don't let me freak you out though, the no-no's of media are steel and marbles ( when it comes to milling things like compositions and BP) and if brass is easily avaliable then by all means use it. Brass has the advantage of being non-toxic as well as having a longer life than lead media.

[moonshot]

In my opinion, based on experience and knowledge about the toxic effects of lead, brass is the best non toxic, non sparking milling media you can use. Looks like you milled up a good 200g batch of BP with the brass. From what I have learned you should use different sets of media to mill oxidizers vs fuels and sulfates vs chlorates etc... to reduce chances of spontaneous combustion.

[marks265]

Since you have both I would try both. Fill up the jar by VOLUME with brass, mill the comp., finish it how ever you like (pulverone, rice, press and corn for example) and test it. Then do the same with the lead (filling it to the same volume as brass) using the same milling time with the same comp. Finish the same as brass was and test. My *theory* is that the lead is heavier and will have more hitting power. Being a sphere alone vs a cylinder should grind more because of surface area of contact point of hit being less vs weight. Where a cylinder hitting broad side would be less effective unless hitting on a corner.

Obviously both will mill but the outcome would be of interest!

[TheSidewinder]

If I didn't know better, Swede, I'd swear that was a picture of *MY* Lortone mill after I opened a freshly-milled batch, though I see you have the QT12 ??? (single 12-pound barrel) versus my QT66 (dual 6-pound barrels)?? Or is that not a Lortone?

 

Same media, too: Brass Rod Stock.

 

It makes excellent media. There's no need to switch to Lead.

 

And, as you have already discovered, the resulting BP is top-notch.

 

TS

[qwezxc12]

I'd save the lead and use it for milling individual chems...especially NH4ClO4. Copper and copper alloys/compounds can sensitize ammonium containing mixtures.

 

I use copper clad .50 cal bullets for BP, charcoal and fuels (hexamine, benzoates, red gum) in my big 12lb. drum. Lead media is reserved exclusively for individual oxidizers in the smaller 6 and 3lb. drums: one lot for Potassium and Ammonium Perchlorates, one batch for KNO3.

 

I do not mill KCLO3 or metals.

[Swede]

Thanks fellas. I like the idea of preserving the lead balls for specific chemicals that may be sensitive to copper alloys, although I do have enough of them to try a BP batch. I know lead is a cumulative poison, and unfortunately as a youth I cast waaaay too many lead balls, figures, sinkers, etc. I would even go running with big lead ingots in my bare hands to get a better workout. My hands would be black with the stuff. Now I am a bit scared of it.

 

By the way, I bought the lead balls from Dixie Gun Works, I think $9 per 100, which isn't bad for pre-cast.

 

TS, the barrel is from one of those Harbor Freight dual rock tumblers that was on sale. I was not too impressed with the tumbler, but the containers are pretty nice. I ended up buying a bigger mill from the guy on eBay, and making a few jars on my own.

 

I like the mill, plenty stout, and effective. One modification I did do...

http://www.5bears.com/firew/bp018.jpg

 

I'm surprised this ball mill doesn't have some sort of a roller stop, so I whipped one up from an old ball bearing and some aluminum stock. Plus, I added a switch to it so I could turn it on and off at the machine if I'm not milling a mixture.

[Swede]

I'm sorry, I forgot this... I was wondering as well about dense ceramic media. I'm thinking ceramic media especially has the potential to be pretty porous, trapping significant amounts of chemical(s) within the pores, if it's finished with anything except a glaze surface. If used only on a particular chemical, and for that one alone, is ceramic generally safe and effective?

 

I understand it's not as dense as metals, but perhaps it can simply be milled for a longer period of time.

 

I know I am full of questions... I'll try not to go totally wild here!

[oskarchem]

This has been discussed though a couple of threads onthe forum but anyway: Some people say that ceramic media could spark, some people say that it wont, but whats the point of messing with your safety...

[KinneticEnergy]

Sorry in advance if this is considered thread hi-jacking...

I didn't think this needed a whole thread to itself.

Does anyone have any experience using urethane replacement drive belts? Like the one sold here http://www.pyrocreations.com/inc/sdetail/22589

 

Would it be worth it?

[Mumbles]

Ceramic would be fine for single component chemicals. While it is porus, the pore are actually relatively large, and the material is easy to clean. That being said I still wouldn't use the media to mill an incompatible chemical. I've heard of other using it for live compositions, but that is just not for me. While they can spark under the right conditions, I don't believe ballmilling will get them to spark, and if it does, it is supposedly not of a high enough energy to ignite BP. Still not something I'd like to disprove the hard way.

 

Ceramic, while not as dense is much harder than any milling metal. While it doesn't pack the same punch as metals might from cascading, the grinding action is still quite good. I believe it should be just as efficient as grinding already fine chemicals. If you drop a brick or a bowling ball on a glass, it will still break.

[TheSidewinder]

Does anyone have any experience using urethane replacement drive belts? Like the one sold here http://www.pyrocreations.com/inc/sdetail/22589

 

Would it be worth it?

If your current belt is shot, a higher-quality replacement is always worth it, in my opinion. The price seems reasonable enough, and it looks like free shipping as well. Not a bad deal at all.

[TheSidewinder]

TS, the barrel is from one of those Harbor Freight dual rock tumblers that was on sale. I was not too impressed with the tumbler, but the containers are pretty nice. I ended up buying a bigger mill from the guy on eBay, and making a few jars on my own.

 

I like the mill, plenty stout, and effective. One modification I did do...

****SNIP*****

Very nice work on the stop roller and barrels, Swede, Nothing like a little ingenuity to solve a problem.

[Swede]

Thank you Sidewinder. On the belts - there is a very special belting material available from a company called Small Parts.

 

It's called Polycord. What it is... a continuous length of a special green thermoset plastc, round in cross-section. It doesn't come in sizes - as I mentioned, it's bought by the length. You determine the length needed, and cut the piece of polycord. Set up a propane torch and a piece of cheap aluminum angle iron. You take both ends of the cord, and simultaneously, with one end in each hand, immerse them into the flame.

 

Within moments, you will get a ball of moletn polycord on each end. Use the angle iron to butt them together, hold for a few moments, and the thermoset plastic will bond instantly. Any excess is trimmed with a razor blade.

 

It's amazing stuff. I've used it for many years, and when "welded" correctly, the weld is as strong as the original belt. You can use round cord in V-pulleys if you'd like, no problems. The neat part about this stuff is that you simply buy 10' or 20' and use it to make any number of belts. The 3/16" would work with a small ball mill; most would opt for the 1/4". It's just another option rather than crummy O-rings and similar. Hopefully someone will find it useful.

[TheSidewinder]

I've seen that general type of drive belting. In the late 90's I worked for a company that had those HUGE Reel-to-Reel Magnetic Tape units. 1/2-inch wide, IIRC.

 

They had a belt for one of the drive cooling components that would occasionally break. (Not the main drive reels, though. Those were actually huge servo motors. Their torque rating was astronomical, and required careful "driving" or they'd twist themselves right off the mounts.)

 

We had an actual kit that accomplished the same thing as Swede's method with the angle iron. Careful trimming with a razor blade, after the repair, was a necessity or the belt would jump off the rollers. That tended to piss off their operators.

[Swede]

While I'm getting my "Ye Olde Pyro Shoppe" together, I was faced with a need for plenty of media barrels of various sizes. I know using blow-out test fittings is nothing new to cap a PVC pipe section neatly, but I may have come up with a couple of simple answers for their metallic content...

 

I had a section of 2" PVC pipe, and was seeing if the test plug would fit. The plug was still in its little bag. So I did this:

 

http://www.5bears.com/firew/bp031.jpg

 

Fit nice, little baggie and all. Then the light bulb turned on. Why not use a piece of HEAVY vinyl sheet, garbage bag, whatever, to wrap the plug and keep the contents of the barrel from touching any part of the plug?

 

They had two styles of plug:

 

http://www.5bears.com/firew/bp033.jpg

 

The one on the left is "Oatey" brand and is a superior style, so I bought a few. Back home, I looked for a source of plastic sheet. In the end, a bag that held doggie rawhide chews became my sheet material. I'm also confident that a piece of "contractor cleanup bag" or better yet a piece of painter's dropcloth would be more than strong enough.

 

Works well...

http://www.5bears.com/firew/bp035.jpg

 

Now all I need to do is test it, after it is trimmed with a razor blade, of course.

 

While I was playing with this, I looked harder at the Oatey plug. If you replaced the carriage bolt in the center with one made of nylon, you need do nothing else, as it is the carriage bolt alone that is the only exposed metal. If you run a whole bunch of smaller drums, in different lengths, this stuff may be helpful. And if it's a repeat, I apologize. Please remember what it was like when you started up... frantic mental activity doesn't begin to describe it.

[justanotherpyro]

I use a length of 4" ABS pipe, two of those fittings, and then 4" rubber caps to give the jar grip on the rollers of my ball mill. They work very nicely.

[Swede]

Another thought - About 3 months ago, I had to buy a length of transparent PVC pipe. I didn't even know there was such a thing, but there is. Perhaps a transparent pipe could be used if you must monitor the process. I'm afraid that talc-fine powder and dust would obscure the view, though.

[FrankRizzo]

Here's a great video showing how RPM effects the motion of the mill charge:

 

http://www.youtube.com/watch?v=KkQuQAF7_S8

 

I believe the channel it's posted on is maintained by one of our members: fizeau. Thanks for the great video!

[tentacles]

Alternatively to covering the carriage bolt with plastic, why not replace it with a stainless steel one? Then you would have the ability to ground any static charge while the mill is running as well (just have a piece of wire rubbing against the end of the bolt). Although the plastic would keep the powder from getting in all those little crevices on the plug.

[JCrewPyros]

That is a great video Frank... Thank you for sharing

[FrankRizzo]

Unfortunately, that plastic will last maybe 5-10 mins before being destroyed. The inside of a ball mill is a very unforgiving environment.

[Apollofrost]

In response to the replacement belt question, you can use those. Or you can buy an o-ring that's the right size for under a dollar.

 

I just went into a local shop that sells o-rings among other nice things and asked for an o-ring the same size as my belt. It's much better quality than the original and only cost me 75 cents with tax.

 

Just my $.02

[pyrogeorge]

@ Swede

can you upload an image with your grinding media?where you bought it?

[Swede]

@ Swede

can you upload an image with your grinding media?where you bought it?

Pipipi, it's nothing more than 3/4" round brass stock, cut into 3/4" lengths. For larger jobs, I cut some 1" diameter rod into 1" lengths. I used a metal-cutting bandsaw, which made short work of it, but with some effort, a hacksaw will do. The cost of brass is insane, but at least it'll last essentially forever.

 

Comparing my attempts so far with lead vs. brass, I like the brass MUCH better. The lead balls seem to gather the chemicals to themselves and hang on tenaciously, whereas the brass media separates very cleanly, and washes much easier than the lead. I am going to go all-brass for future milling projects.