Ball mill media type

[passgas]

It has been a while since I last posted on this forum. The ball mill I made works better than expected( 2 hours mill time max). Running a 6" jar with 60 cal lead balls at a good 70 rpm. I make strictly bp for a small cannon.

 

Question I have is I want to make a couple of jasr to mill charcoal/sulfur together and then the other jar just for potassium nitrate. Plan on then mixing the two instead of milling together, This time around I want to try using 1/2 hard drawn copper pipe filled with lead. My question is what would the ideal length I should cut the 1/2 copper pipe?

[NeighborJ]

1/2"×1/2" sorta, the OD would be 5/8" so cut them square at 5/8". Edited November 21, 2019 by NeighborJ

[passgas]

So I make them the same length as the outside diameter, Round ball in a tube form.That's going to be a lot of cutting.

[NeighborJ]

A portaban would make short work of it. You could always buy the round media from Woodysrocks.com

[Mumbles]

Using 3/4" copper, so ~7/8" OD x about the same length requires about 150 pieces. Using 5/8" OD x about as long would probably take 200-230 I'd guess? This is why a lot of people don't tend to go this route. About the only quick-ish way to do this is with a horizontal bandsaw. Large buckshot forms to make round balls eliminates the cutting, but slows down the pouring. Some pyro tooling suppliers used to sell aluminum molds to make cylindrical media. I think it was Wolter, but Woody or Ben Smith should be able to whip something up.

 

Another option might be to cast longer ingots inside the copper tube, eject the lead, and cut the lead itself. Using a release like thinned out vaseline and preheating the tubes helps prevent it from binding to the copper. You'll still probably get a few stuck. Yet another alternative is to pour them into longer copper tubes, and cut them after they've cooled. Again, it still doesn't eliminate the cutting.

[passgas]

I do have a couple of high quality tubing cutters from my job.These cutters were made to cut stainless steel tubing. I like tubing cutters because of the clean,

square cut you get. Seems like everyone likes the same dia. to length. What happens if you have a 5/8 outside dia and you go 1" length? Cut them up and pour lead.

Does it changes the grinding characteristics of your mill?( I sure like to do things the hard way sometimes)

[fredjr]

From experience, I don't recommend using copper pipe at all. The copper will corrode & over time it will start to fall apart and you will have bits of cooper coming off which you will have to screen out. A simple way to cast without an expensive mold is drill appropriate size holes in a board. But better to just get ceramic media...

[memo]

lead ball are safe and do a good job, why mess around with things that will probably work. i dont like rods or mixing rods and balls you end up with deformed balls. i think it is better to keep it simple. i use round fishing weights. that is all i can find

[justvisiting]

Hardened lead is definitely the best media for black powder, since it's non-sparking and heavy. If you plan to do double + single component milling, the media milling the charcoal/sulfur is going to take quite a beating. If you were to use any type of lead media for that, you will be getting whole gram quantities of lead in each batch.

 

Personally, I like stainless steel media best for milling charcoal. To mill it superfine, I like small media, like 5/16", or 3/8". 1/2" works though, and is ideal for milling potassium nitrate also. It's expensive, but lasts forever, and is easy to clean. I've milled complete BP with S.S. as well, but there is the remote possibility of sparking. Personally, I'd feel safer (not safe) milling BP with stainless steel than I would using ceramic media the same way. The extreme hardness of ceramic is the source of my concern.

 

Ceramic media is the least efficient media I've used, and the stuff I bought (likely factory seconds) started to degrade after many uses.

 

1/2" brass rod stock, painstakingly cut to length, might be a much better alternative than casting lead into a sleeve.

[memo]

why not jusr make a rod mill, dont have to cut into little pieces. rod mills do work very well. google is your friend

[justvisiting]

I was going to make a rod mill, but could not find ONE example of a rod mill made on anything less than an industrial scale. They use them for crushing rocks. I couldn't imagine using one for hobbyist scale pyro. I doubt anyone has done it. If so, I'd like to see pictures! I liked the idea of separating the media by pulling out the rods and wiping them off, rather than screening a bunch of balls. I wanted to make a rod mill because I was unsatisfied with the fineness of my milled charcoal that I used to make screen-mixed BP. I bought the rods and a cylinder, but I never got to it, because I was gifted thousands of stainless steel spheres and my problem was solved.

[passgas]

I may try a rod mill just to see what happens. The little research says to rotate at a slower speed than

what a ball mill runs. I will try at the speed I am running now. I will post if I try this. I should do a little more reading

and see if I could come out with a game plan. I like trying to do something new especially something I am pretty green about.

Will take me some time before I start

[Arthur]

Rod mills work BUT the first mode of failure is a tangle, then you need to fill it with new rods.

 

https://www.inoxia.co.uk

 

supply good ceramic media and ship internationally for inert items.

Edited November 23, 2019 by Arthur

[Arthur]

From reading elswhere,6 to 18% of antimony is used to harden lead. or the lead is bought as hard lead

 

http://mysite.du.edu/~jcalvert/phys/lead.htm#Prod-Lead

 

Linotype alloy was 4%tin, 12% antimony in lead.

[robbo]

Re: hardened lead...

 

I cast long cylinders of linotype into copper pipe lined with a couple of turns of paper resulting in approx. 1/2" diam. bars a foot or so long (because that's how long the printer paper is). Cooling shrinks the slugs and they slip out, sometimes with the paper stuck to them. As soon as they're cool enough I snip them up into 1/2" slugs with a small bolt cutter. If I wait longer hardening occurs and they don't snip regularly; looks like some crystallization/metallurgy starts to take place within a day. Any remaining scorched paper wears off when I mill them for an hour or two with sawdust to clean and round off the edges. About 70 pounds, 2 jars' worth, only took an afternoon once I got the system streamlined. I dedicated all this media to just milling BP.

 

I'm becoming a fan of super-milling my charcoal with SS as long as I want to endure the mess. This really cuts down on the 3-component BP mill time; If I use pre-milled KNO3 I can get a jar finished in about 45 minutes. Maybe all I'm really doing at that point is doing a very thorough mixing job?

 

One of these days I'll get around to trying JustVisiting's complete no-mill method. Super-milled hot charcoal is quite a mess to handle by itself. Reminds me of lampblack, almost.

[justvisiting]

Robbo, I'm a little surprised that you find super-milled charcoal messy to handle. I find that it is quite dense and has very little tendency to become airborne. For me, even super-milled balsa charcoal is just as dense as willow. I'm using small SS media and milling for 6 hours though. I'm a little on the fence about safety when it comes to incorporation by screening vs. using a short mill time. The short mill time has risk, but it's remote- or it should be Separating the media is the riskiest part, IMO. OTOH, screening large batches twice through 40 mesh puts a lot of facetime into the process, which carries 'some' risk also. It's too bad brass spheres are so expensive. They would be ideal for charcoal and BP.

 

That's a cool tip about the paper. Lots of folks like to leave the copper sleeves on, but I don't care for that approach.

[robbo]

JV:

 

I'm just used to dumping coarse KNO3, dried cooked ERC chips and S into a drum and letting it run just because that's how I've set everything up. And I'm a slob with AFCs.

 

But better methods speak for themselves. I notice that your ideas meet with skepticism wherever you post but I need no convincing about supermilling. The advantages are obvious to me and I'll take it towards your natural conclusion. We resist change.

 

I'm with you on mixing in the mill vs a thorough screen mix; the advantage to the latter is clear. I'm not a BP speed fanatic; easy to make, workhorse powder is my endpoint.

[SharkWhisperer]

I, too, don't find airfloat milled charcoal to be too much of an issue, whether from ERC chips, collected willow branches, or alder shingles/slats. Mill it up, separate media in a colander over a big lipped tray (outside), and spoon/pour it into it's new container. Simples

 

What I DO find problematic is the hell that I caught when I dropped a pound of airfloat when I was pulling the tray out of the oven. Woman wasn't too pleased and the cleanup, though not difficult on a white kitchen tile floor, required several rolls of wet and dry paper towels (after I swept/recovered what I was able, ack!). For milling BP, I always cook excess water out if it's been stored over a month or so, to prevent potential clumping. KNO₃, too. Makes life simpler. Dessicant packs help, too (silica), but not always ideal (esp for charcoal).

 

Now making blackmatch, that's another scenario--I am forever leaving little black splotches on any nearby surface. At least it's easy to clean up... Or if I'm rebagging airfloat for any reason, well, some always makes an escape and a minor mess somehow...

[Scotty123]

"hell that I caught when I dropped a pound of airfloat when I was pulling the tray out of the oven"

If you have shop space, check Craigslist for a used oven for cheap (people want a different color or newer). Electric ovens often run around $50. You will need to hook up a stove outlet.