Making Copper-lead media

[BlastFromThePast]

I've seen a few pictures of media like this where they take copper tubing and melt lead inside of it. Could someone walk me through how one goes about making it. Melting the lead is pretty self explanatory but do you just pour the lead into an upright section of copper or dip the copper in the molten lead? Also, what's a good ID copper pipe to buy for this type of media? I have a crap load (5lbs) of .300 lead buck buckshot that I can melt. Is this going to be enough lead or should I go out and get some more. Edited April 2, 2013 by BlastFromThePast

[Mumbles]

I generally hear this being done with brass, but copper should work too. You just melt the lead and pour it into cut up segments of tubing. There is sometimes a problem with the lead shrinking and falling out or coming loose. This can be prevented by overfilling slightly, and compressing the lead (swaging) once cool with an arbor press or hydraulic press.

 

Diameter and quantity of lead will depend entirely on what size your mill is. Copper with a diameter from 1/2 to 3/4" is fairly common for this use.

[Oinikis]

so, it is used as media together with the pipe? so the lead is for weight, and the copper for hardeness?

[BlastFromThePast]

Yeah, I would imagine that brass would make for more durable media than copper but the lead is the weight. I've heard that this media can greatly reduce milling time, assuming you start out with pretty fine chems

[Mumbles]

Hardened lead can and does approach the hardness of brass and copper. This however tends to make it a little easier to cast the lead, as well as not necessarily requiring hardened lead, or the various hardening procedures. Probably the worst part about making this is cutting all the tubes.

 

I'd suspect it to mill with around the same generally efficiency as lead.

[Bobosan]

Swaging the lead into the tubes will most likely be necessary because of shrinkage. You could preheat the tubes to molten lead temp and then pour. This would at least allow for a complete smooth fill without voids and even cooling but the lead will still tend to shrink more than the brass or copper. This is based on pure lead and don't know how much adding antimony to the lead changes shrink rate. Tin would reduce the shrink rate.

 

http://www.nonesucht...mkr/shrink.html

 

edit - I thought Dagabu had some pics in his gallery of lead filled copper media but can't find it now. Anyway, check this thread out for more info on lead filled copper media.

 

http://www.amateurpyro.com/forums/topic/7198-copperlead-media/page__hl__+lead%20+filled%20+copper#entry94543

Edited April 2, 2013 by Bobosan

[BlastFromThePast]

Question, if I were to use the .300 buckshot, how much longer can I expect milling to take? I'm assuming it would still do the job, just take longer, no?

[Mumbles]

I used to use 00 buckshot, which is slightly larger. It actually mills very efficiently, but you need to have a relatively fine particle size to start with. Smaller media have more impacts per unit time, but those impact have proportionally less energy as the balls are lighter and fall a shorter distance on average. Due to this, the media has next to no crushing power, but excellent grinding power. If you pre-grind everything to -30 mesh or so, you should be good to go.

[Oinikis]

i use lead shots which are about 5mm (1/5"). i start with coffemilled chems and it mills very good. Edited April 3, 2013 by Oinikis

[BlastFromThePast]

Smaller media have more impacts per unit time, but those impact have proportionally less energy as the balls are lighter and fall a shorter distance on average. Due to this, the media has next to no crushing power, but excellent grinding power.

 

Does this mean that media with a larger diameter has more crushing power and less grinding power or are both greater?

[dagabu]

I generally hear this being done with brass, but copper should work too. You just melt the lead and pour it into cut up segments of tubing. There is sometimes a problem with the lead shrinking and falling out or coming loose. This can be prevented by overfilling slightly, and compressing the lead (swaging) once cool with an arbor press or hydraulic press.

 

Diameter and quantity of lead will depend entirely on what size your mill is. Copper with a diameter from 1/2 to 3/4" is fairly common for this use.

 

+1, this is what Mum is talking about:

 

[dagabu]

Does this mean that media with a larger diameter has more crushing power and less grinding power or are both greater?

 

Yes, that is exactly what that means. The energy a large object imparts on a pile is greater than a smaller object but the number of strikes smaller objects make in a falling heap is much greater and does a better job at grinding smaller chems.

[BlastFromThePast]

So lead media of 3/8" would probably not be able to process my charcoal? I'm talking about C that has been crudely ground up after cooking but still contains pieces as big as 1/4".

[dagabu]

So lead media of 3/8" would probably not be able to process my charcoal? I'm talking about C that has been crudely ground up after cooking but still contains pieces as big as 1/4".

 

I would think that as long as the media is larger than the charcoal, you should be fine. I use 3/8" and it works fantastic!

[Mumbles]

As I said, I had 00 buckshot, which is about .33" in diameter. In a 6" jar, it could not totally process willow charcoal directly from my meat grinder or bucket/fence post screened to pass a 4 mesh screen. I had to grind it additionally for it to be totally powdered. This was over a 4hr period. It would also barely touch prilled KNO3.

 

My jar did not have lifter bars in it. Perhaps with something to ensure the break angle was close to optimal it would have done a better job. I'm sure it also depends on your particular charcoal. I was using willow from custom charcoal at the time, which does have a few undercooked and harder pieces in it. A very soft charcoal probably would have had no problems.

 

There are a lot of differing opinions on this matter. Larger media certainly had more crushing power. Smaller media certainly has more impacts per minute. There is some data that suggests that smaller media will yield an ultimately finer powder at the end. When all is said and done, when I build a new mill, I am going to probably use a larger media than I did last time. The ability to crush lump charcoal and granular components is more important to me. If it takes me an extra half hour of milling, so be it. There are much bigger factors affecting final BP quality than the size of your media.

[Bobosan]

I don't think I have my mill optimized for ideal RPM but it cranks out airfloat from sticks in 2 hours. Same with prilled KNO3. Mumbles mentioned lifter bars and I think the octagon shaped barrels may also have a lot to do with milling success.

[dagabu]

This is one of the places that mum and differ. I am using Zirc-M for media and it turns kno3 prills into powder in 20 minutes. I use that copper filled lead to crush charcoal and just pour it out over a 1/4" mesh screen and throw the stuff back in the jar that doesn't pass. I am also using four different jars, one for anything charcoal related, one for metals, one for benzo and Sali and one for Perc.

 

I also have media that i use just for one type of chem.

[Bobosan]

.............I am also using four different jars, one for anything charcoal related, one for metals, one for benzo and Sali and one for Perc.

 

I also have media that i use just for one type of chem.

 

That would be the safest way.

 

I used the 15lb octagon barrel just one time for a test run of larger batch of KNO3 prills with lead media. Didn't care for the discolored results and surely emitted lead elements when burned, not to mention how that might affect other composition performance. I use alumina ceramic now in the 6lb HF mill to do the KNO3. No contamination and gets it to fine powder in 2 hours.

 

Getting back to your lead filled copper media, would it be more economical in time and money to just use solid copper or brass rod? Seems like a lot of work went into those 1/2" copper tubes not to mention copper pipe ain't cheap either.

Edited April 9, 2013 by Bobosan